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0704.0001

Pavel Nadolsky

C. Bal\'azs, E. L. Berger, P. M. Nadolsky, C.-P. Yuan

Calculation of prompt diphoton production cross sections at Tevatron and LHC energies

37 pages, 15 figures; published version

Phys.Rev.D76:013009,2007

10.1103/PhysRevD.76.013009

ANL-HEP-PR-07-12

hep-ph

A fully differential calculation in perturbative quantum chromodynamics is presented for the production of massive photon pairs at hadron colliders. All next-to-leading order perturbative contributions from quark-antiquark, gluon-(anti)quark, and gluon-gluon subprocesses are included, as well as all-orders resummation of initial-state gluon radiation valid at next-to-next-to-leading logarithmic accuracy. The region of phase space is specified in which the calculation is most reliable. Good agreement is demonstrated with data from the Fermilab Tevatron, and predictions are made for more detailed tests with CDF and DO data. Predictions are shown for distributions of diphoton pairs produced at the energy of the Large Hadron Collider (LHC). Distributions of the diphoton pairs from the decay of a Higgs boson are contrasted with those produced from QCD processes at the LHC, showing that enhanced sensitivity to the signal can be obtained with judicious selection of events.

2008-11-26

0704.0009

Paul Harvey

Paul Harvey, Bruno Merin, Tracy L. Huard, Luisa M. Rebull, Nicholas Chapman, Neal J. Evans II, Philip C. Myers

The Spitzer c2d Survey of Large, Nearby, Insterstellar Clouds. IX. The Serpens YSO Population As Observed With IRAC and MIPS

Astrophys.J.663:1149-1173,2007

10.1086/518646

astro-ph

We discuss the results from the combined IRAC and MIPS c2d Spitzer Legacy observations of the Serpens star-forming region. In particular we present a set of criteria for isolating bona fide young stellar objects, YSO's, from the extensive background contamination by extra-galactic objects. We then discuss the properties of the resulting high confidence set of YSO's. We find 235 such objects in the 0.85 deg^2 field that was covered with both IRAC and MIPS. An additional set of 51 lower confidence YSO's outside this area is identified from the MIPS data combined with 2MASS photometry. We describe two sets of results, color-color diagrams to compare our observed source properties with those of theoretical models for star/disk/envelope systems and our own modeling of the subset of our objects that appear to be star+disks. These objects exhibit a very wide range of disk properties, from many that can be fit with actively accreting disks to some with both passive disks and even possibly debris disks. We find that the luminosity function of YSO's in Serpens extends down to at least a few x .001 Lsun or lower for an assumed distance of 260 pc. The lower limit may be set by our inability to distinguish YSO's from extra-galactic sources more than by the lack of YSO's at very low luminosities. A spatial clustering analysis shows that the nominally less-evolved YSO's are more highly clustered than the later stages and that the background extra-galactic population can be fit by the same two-point correlation function as seen in other extra-galactic studies. We also present a table of matches between several previous infrared and X-ray studies of the Serpens YSO population and our Spitzer data set.

2010-03-18

0704.0015

Christian Stahn

Christian Stahn

Fermionic superstring loop amplitudes in the pure spinor formalism

22 pages; signs and coefficients adjusted for anticommuting superfields, section 4.3 changed accordingly, reference added

JHEP 0705:034,2007

10.1088/1126-6708/2007/05/034

hep-th

The pure spinor formulation of the ten-dimensional superstring leads to manifestly supersymmetric loop amplitudes, expressed as integrals in pure spinor superspace. This paper explores different methods to evaluate these integrals and then uses them to calculate the kinematic factors of the one-loop and two-loop massless four-point amplitudes involving two and four Ramond states.

2009-11-13

0704.0016

Li Tong

Chao-Hsi Chang, Tong Li, Xue-Qian Li and Yu-Ming Wang

Lifetime of doubly charmed baryons

17 pages, 3 figures and 1 table

Commun.Theor.Phys.49:993-1000,2008

10.1088/0253-6102/49/4/38

hep-ph

In this work, we evaluate the lifetimes of the doubly charmed baryons $\Xi_{cc}^{+}$, $\Xi_{cc}^{++}$ and $\Omega_{cc}^{+}$. We carefully calculate the non-spectator contributions at the quark level where the Cabibbo-suppressed diagrams are also included. The hadronic matrix elements are evaluated in the simple non-relativistic harmonic oscillator model. Our numerical results are generally consistent with that obtained by other authors who used the diquark model. However, all the theoretical predictions on the lifetimes are one order larger than the upper limit set by the recent SELEX measurement. This discrepancy would be clarified by the future experiment, if more accurate experiment still confirms the value of the SELEX collaboration, there must be some unknown mechanism to be explored.

2008-12-18

0704.0017

Nceba Mhlahlo

Nceba Mhlahlo, David H. Buckley, Vikram S. Dhillon, Steven B. Potter, Brian Warner and Patric A. Woudt

Spectroscopic Observations of the Intermediate Polar EX Hydrae in Quiescence

10 pages, 11 figures (figures 3, 4, 7 and 8 at reduced resolution, originals available on request). Accepted for publication in Monthly Notices of the Royal Astronomical Society

Mon.Not.Roy.Astron.Soc.378:211-220,2007

10.1111/j.1365-2966.2007.11762.x

astro-ph

Results from spectroscopic observations of the Intermediate Polar (IP) EX Hya in quiescence during 1991 and 2001 are presented. Spin-modulated radial velocities consistent with an outer disc origin were detected for the first time in an IP. The spin pulsation was modulated with velocities near ~500-600 km/s. These velocities are consistent with those of material circulating at the outer edge of the accretion disc, suggesting corotation of the accretion curtain with material near the Roche lobe radius. Furthermore, spin Doppler tomograms have revealed evidence of the accretion curtain emission extending from velocities of ~500 km/s to ~1000 km/s. These findings have confirmed the theoretical model predictions of King & Wynn (1999), Belle et al. (2002) and Norton et al. (2004) for EX Hya, which predict large accretion curtains that extend to a distance close to the Roche lobe radius in this system. Evidence for overflow stream of material falling onto the magnetosphere was observed, confirming the result of Belle et al. (2005) that disc overflow in EX Hya is present during quiescence as well as outburst. It appears that the hbeta and hgamma spin radial velocities originated from the rotation of the funnel at the outer disc edge, while those of halpha were produced due to the flow of material along the field lines far from the white dwarf (narrow component) and close to the white dwarf (broad-base component), in agreement with the accretion curtain model.

2009-06-23

0704.0018

Andreas Gustavsson

Andreas Gustavsson

In quest of a generalized Callias index theorem

20 pages, v2: an overall sign and typos corrected

hep-th

We give a prescription for how to compute the Callias index, using as regulator an exponential function. We find agreement with old results in all odd dimensions. We show that the problem of computing the dimension of the moduli space of self-dual strings can be formulated as an index problem in even-dimensional (loop-)space. We think that the regulator used in this Letter can be applied to this index problem.

2007-05-23

0704.0023

Maria Loukitcheva

M. A. Loukitcheva, S. K. Solanki and S. White

ALMA as the ideal probe of the solar chromosphere

4 pages, 2 figures, to appear in the proceedings of the conference Science with ALMA: a new era for Astrophysics, Spain, 2006

Astrophys.Space Sci.313:197-200,2008

10.1007/s10509-007-9626-1

astro-ph

The very nature of the solar chromosphere, its structuring and dynamics, remains far from being properly understood, in spite of intensive research. Here we point out the potential of chromospheric observations at millimeter wavelengths to resolve this long-standing problem. Computations carried out with a sophisticated dynamic model of the solar chromosphere due to Carlsson and Stein demonstrate that millimeter emission is extremely sensitive to dynamic processes in the chromosphere and the appropriate wavelengths to look for dynamic signatures are in the range 0.8-5.0 mm. The model also suggests that high resolution observations at mm wavelengths, as will be provided by ALMA, will have the unique property of reacting to both the hot and the cool gas, and thus will have the potential of distinguishing between rival models of the solar atmosphere. Thus, initial results obtained from the observations of the quiet Sun at 3.5 mm with the BIMA array (resolution of 12 arcsec) reveal significant oscillations with amplitudes of 50-150 K and frequencies of 1.5-8 mHz with a tendency toward short-period oscillations in internetwork and longer periods in network regions. However higher spatial resolution, such as that provided by ALMA, is required for a clean separation between the features within the solar atmosphere and for an adequate comparison with the output of the comprehensive dynamic simulations.

2009-06-23

0704.0029

Weizhen Deng

Zhan Shu, Xiao-Lin Chen and Wei-Zhen Deng

Understanding the Flavor Symmetry Breaking and Nucleon Flavor-Spin Structure within Chiral Quark Model

Phys.Rev.D75:094018,2007

10.1103/PhysRevD.75.094018

hep-ph

In $\XQM$, a quark can emit Goldstone bosons. The flavor symmetry breaking in the Goldstone boson emission process is used to intepret the nucleon flavor-spin structure. In this paper, we study the inner structure of constituent quarks implied in $\XQM$ caused by the Goldstone boson emission process in nucleon. From a simplified model Hamiltonian derived from $\XQM$, the intrinsic wave functions of constituent quarks are determined. Then the obtained transition probabilities of the emission of Goldstone boson from a quark can give a reasonable interpretation to the flavor symmetry breaking in nucleon flavor-spin structure.

2010-04-23

0704.0031

Valery M. Biryukov

V. M. Biryukov (Serpukhov, IHEP)

Crystal channeling of LHC forward protons with preserved distribution in phase space

11 pages, 3 figures

Phys.Lett.B658:7-12,2007

10.1016/j.physletb.2007.10.051

hep-ph

We show that crystal can trap a broad (x, x', y, y', E) distribution of particles and channel it preserved with a high precision. This sampled-and-hold distribution can be steered by a bent crystal for analysis downstream. In simulations for the 7 TeV Large Hadron Collider, a crystal adapted to the accelerator lattice traps 90% of diffractively scattered protons emerging from the interaction point with a divergence 100 times the critical angle. We set the criterion for crystal adaptation improving efficiency ~100-fold. Proton angles are preserved in crystal transmission with accuracy down to 0.1 microrad. This makes feasible a crystal application for measuring very forward protons at the LHC.

2008-11-26

0704.0032

Andreu Esteban-Pretel

A. Esteban-Pretel, R. Tom\`as and J. W. F. Valle

Probing non-standard neutrino interactions with supernova neutrinos

21 pages, 12 figures, 17 postscript files

Phys.Rev.D76:053001,2007

10.1103/PhysRevD.76.053001

hep-ph

We analyze the possibility of probing non-standard neutrino interactions (NSI, for short) through the detection of neutrinos produced in a future galactic supernova (SN).We consider the effect of NSI on the neutrino propagation through the SN envelope within a three-neutrino framework, paying special attention to the inclusion of NSI-induced resonant conversions, which may take place in the most deleptonised inner layers. We study the possibility of detecting NSI effects in a Megaton water Cherenkov detector, either through modulation effects in the $\bar\nu_e$ spectrum due to (i) the passage of shock waves through the SN envelope, (ii) the time dependence of the electron fraction and (iii) the Earth matter effects; or, finally, through the possible detectability of the neutronization $\nu_e$ burst. We find that the $\bar\nu_e$ spectrum can exhibit dramatic features due to the internal NSI-induced resonant conversion. This occurs for non-universal NSI strengths of a few %, and for very small flavor-changing NSI above a few$\times 10^{-5}$.

2008-11-26

0704.0052

William Gordon Ritter

Arthur Jaffe (1) and Gordon Ritter (1) ((1) Harvard University)

Quantum Field Theory on Curved Backgrounds. II. Spacetime Symmetries

18 pages, 1 figure

hep-th

We study space-time symmetries in scalar quantum field theory (including interacting theories) on static space-times. We first consider Euclidean quantum field theory on a static Riemannian manifold, and show that the isometry group is generated by one-parameter subgroups which have either self-adjoint or unitary quantizations. We analytically continue the self-adjoint semigroups to one-parameter unitary groups, and thus construct a unitary representation of the isometry group of the associated Lorentzian manifold. The method is illustrated for the example of hyperbolic space, whose Lorentzian continuation is Anti-de Sitter space.

2007-05-23

0704.0059

Thomas Beatty

T. G. Beatty, J. M. Fernandez, D. W. Latham, G. A. Bakos, G. Kovacs, R. W. Noyes, R. P. Stefanik, G. Torres, M. E. Everett, C. W. Hergenrother

The Mass and Radius of the Unseen M-Dwarf Companion in the Single-Lined Eclipsing Binary HAT-TR-205-013

18 pages, 9 tables and 6 figures; accepted by ApJ. Added a reference and corrected a typo

Astrophys.J.663:573-582,2007

10.1086/518413

astro-ph

We derive masses and radii for both components in the single-lined eclipsing binary HAT-TR-205-013, which consists of a F7V primary and a late M-dwarf secondary. The system's period is short, $P=2.230736 \pm 0.000010$ days, with an orbit indistinguishable from circular, $e=0.012 \pm 0.021$. We demonstrate generally that the surface gravity of the secondary star in a single-lined binary undergoing total eclipses can be derived from characteristics of the light curve and spectroscopic orbit. This constrains the secondary to a unique line in the mass-radius diagram with $M/R^2$ = constant. For HAT-TR-205-013, we assume the orbit has been tidally circularized, and that the primary's rotation has been synchronized and aligned with the orbital axis. Our observed line broadening, $V_{\rm rot} \sin i_{\rm rot} = 28.9 \pm 1.0$ \kms, gives a primary radius of $R_{\rm A} = 1.28 \pm 0.04$ \rsun. Our light curve analysis leads to the radius of the secondary, $R_{\rm B} = 0.167 \pm 0.006$ \rsun, and the semimajor axis of the orbit, $a = 7.54 \pm 0.30 \rsun = 0.0351 \pm 0.0014$ AU. Our single-lined spectroscopic orbit and the semimajor axis then yield the individual masses, $M_{\rm B} = 0.124 \pm 0.010$ \msun and $M_{\rm A} = 1.04 \pm 0.13$ \msun. Our result for HAT-TR-205-013 B lies above the theoretical mass-radius models from the Lyon group, consistent with results from double-lined eclipsing binaries. The method we describe offers the opportunity to study the very low end of the stellar mass-radius relation.

2009-06-23

0704.0063

Somnath Choudhury

Somnath Choudhury

Experimental efforts in search of 76Ge Neutrinoless Double Beta Decay

hep-ph

Neutrinoless double beta decay is one of the most sensitive approaches in non-accelerator particle physics to take us into a regime of physics beyond the standard model. This article is a brief review of the experiments in search of neutrinoless double beta decay from 76Ge. Following a brief introduction of the process of double beta decay from 76Ge, the results of the very first experiments IGEX and Heidelberg-Moscow which give indications of the existence of possible neutrinoless double beta decay mode has been reviewed. Then ongoing efforts to substantiate the early findings are presented and the Majorana experiment as a future experimental approach which will allow a very detailed study of the neutrinoless decay mode is discussed.

2008-03-12

0704.0064

Rudra Prakash Malik

R. P. Malik (Bhu)

Nilpotent symmetry invariance in the superfield formulation: the (non-)Abelian 1-form gauge theories

LaTeX file, 19 pages, journal reference

Int.J.Mod.Phys.A23:3685-3705,2008

10.1142/S0217751X08041591

hep-th

http://arxiv.org/licenses/nonexclusive-distrib/1.0/

We capture the off-shell as well as the on-shell nilpotent Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry invariance of the Lagrangian densities of the four (3 + 1)-dimensional (4D) (non-)Abelian 1-form gauge theories within the framework of the superfield formalism. In particular, we provide the geometrical interpretations for (i) the above nilpotent symmetry invariance, and (ii) the above Lagrangian densities, in the language of the specific quantities defined in the domain of the above superfield formalism. Some of the subtle points, connected with the 4D (non-)Abelian 1-form gauge theories, are clarified within the framework of the above superfield formalism where the 4D ordinary gauge theories are considered on the (4, 2)-dimensional supermanifold parametrized by the four spacetime coordinates x^\mu (with \mu = 0, 1, 2, 3) and a pair of Grassmannian variables \theta and \bar\theta. One of the key results of our present investigation is a great deal of simplification in the geometrical understanding of the nilpotent (anti-)BRST symmetry invariance.

2008-11-26

0704.0066

Bozhidar Zakhariev Iliev

Bozhidar Z. Iliev (Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria)

Lagrangian quantum field theory in momentum picture. IV. Commutation relations for free fields

60 LaTeX pages. The packages AMS-LaTeX and amsfonts are required. This paper is a continuation of the e-print E-prints No. hep-th/0402006, No. hep-th/0405008 and No. hep-th/0505007. For related papers, visit the "publication" pages at http://theo.inrne.bas.bg/~bozho/

hep-th

Possible (algebraic) commutation relations in the Lagrangian quantum theory of free (scalar, spinor and vector) fields are considered from mathematical view-point. As sources of these relations are employed the Heisenberg equations/relations for the dynamical variables and a specific condition for uniqueness of the operators of the dynamical variables (with respect to some class of Lagrangians). The paracommutation relations or some their generalizations are pointed as the most general ones that entail the validity of all Heisenberg equations. The simultaneous fulfillment of the Heisenberg equations and the uniqueness requirement turn to be impossible. This problem is solved via a redefinition of the dynamical variables, similar to the normal ordering procedure and containing it as a special case. That implies corresponding changes in the admissible commutation relations. The introduction of the concept of the vacuum makes narrow the class of the possible commutation relations; in particular, the mentioned redefinition of the dynamical variables is reduced to normal ordering. As a last restriction on that class is imposed the requirement for existing of an effective procedure for calculating vacuum mean values. The standard bilinear commutation relations are pointed as the only known ones that satisfy all of the mentioned conditions and do not contradict to the existing data.

2007-05-23

0704.0080

Dean McLaughlin

Dean E. McLaughlin and S. Michael Fall

Shaping the Globular Cluster Mass Function by Stellar-Dynamical Evaporation

Final version, matching the published paper

Astrophys.J.679:1272-1287,2008

10.1086/533485

astro-ph

http://arxiv.org/licenses/nonexclusive-distrib/1.0/

We show that the globular cluster mass function (GCMF) in the Milky Way depends on cluster half-mass density (rho_h) in the sense that the turnover mass M_TO increases with rho_h while the width of the GCMF decreases. We argue that this is the expected signature of the slow erosion of a mass function that initially rose towards low masses, predominantly through cluster evaporation driven by internal two-body relaxation. We find excellent agreement between the observed GCMF -- including its dependence on internal density rho_h, central concentration c, and Galactocentric distance r_gc -- and a simple model in which the relaxation-driven mass-loss rates of clusters are approximated by -dM/dt = mu_ev ~ rho_h^{1/2}. In particular, we recover the well-known insensitivity of M_TO to r_gc. This feature does not derive from a literal ``universality'' of the GCMF turnover mass, but rather from a significant variation of M_TO with rho_h -- the expected outcome of relaxation-driven cluster disruption -- plus significant scatter in rho_h as a function of r_gc. Our conclusions are the same if the evaporation rates are assumed to depend instead on the mean volume or surface densities of clusters inside their tidal radii, as mu_ev ~ rho_t^{1/2} or mu_ev ~ Sigma_t^{3/4} -- alternative prescriptions that are physically motivated but involve cluster properties (rho_t and Sigma_t) that are not as well defined or as readily observable as rho_h. In all cases, the normalization of mu_ev required to fit the GCMF implies cluster lifetimes that are within the range of standard values (although falling towards the low end of this range). Our analysis does not depend on any assumptions or information about velocity anisotropy in the globular cluster system.

2010-11-11

0704.0083

Andrei Barvinsky

A.O.Barvinsky

Why there is something rather than nothing (out of everything)?

4 pages, RevTex, several references added and minor changes done

Phys.Rev.Lett.99:071301,2007

10.1103/PhysRevLett.99.071301

hep-th

The path integral over Euclidean geometries for the recently suggested density matrix of the Universe is shown to describe a microcanonical ensemble in quantum cosmology. This ensemble corresponds to a uniform (weight one) distribution in phase space of true physical variables, but in terms of the observable spacetime geometry it is peaked about complex saddle-points of the {\em Lorentzian} path integral. They are represented by the recently obtained cosmological instantons limited to a bounded range of the cosmological constant. Inflationary cosmologies generated by these instantons at late stages of expansion undergo acceleration whose low-energy scale can be attained within the concept of dynamically evolving extra dimensions. Thus, together with the bounded range of the early cosmological constant, this cosmological ensemble suggests the mechanism of constraining the landscape of string vacua and, simultaneously, a possible solution to the dark energy problem in the form of the quasi-equilibrium decay of the microcanonical state of the Universe.

2008-11-26

0704.0085

Partha Mukhopadhyay

Partha Mukhopadhyay

A Universality in PP-Waves

LaTeX file, 43 pages, one reference added, minor changes made

JHEP 0706:061,2007

10.1088/1126-6708/2007/06/061

DAMTP-2007-30

hep-th

We discuss a universality property of any covariant field theory in space-time expanded around pp-wave backgrounds. According to this property the space-time lagrangian density evaluated on a restricted set of field configurations, called universal sector, turns out to be same around all the pp-waves, even off-shell, with same transverse space and same profiles for the background scalars. In this paper we restrict our discussion to tensorial fields only. In the context of bosonic string theory we consider on-shell pp-waves and argue that universality requires the existence of a universal sector of world-sheet operators whose correlation functions are insensitive to the pp-wave nature of the metric and the background gauge flux. Such results can also be reproduced using the world-sheet conformal field theory. We also study such pp-waves in non-polynomial closed string field theory (CSFT). In particular, we argue that for an off-shell pp-wave ansatz with flat transverse space and dilaton independent of transverse coordinates the field redefinition relating the low energy effective field theory and CSFT with all the massive modes integrated out is at most quadratic in fields. Because of this simplification it is expected that the off-shell pp-waves can be identified on the two sides. Furthermore, given the massless pp-wave field configurations, an iterative method for computing the higher massive modes using the CSFT equations of motion has been discussed. All our bosonic string theory analyses can be generalised to the common Neveu-Schwarz sector of superstrings.

2009-11-13

0704.0094

HongSheng Zhao

HongSheng Zhao (SUPA, St Andrews)

Timing and Lensing of the Colliding Bullet Clusters: barely enough time and gravity to accelerate the bullet

5-pages, Physical Review D, rapid publication submitted

astro-ph

We present semi-analytical constraint on the amount of dark matter in the merging bullet galaxy cluster using the classical Local Group timing arguments. We consider particle orbits in potential models which fit the lensing data. {\it Marginally consistent} CDM models in Newtonian gravity are found with a total mass M_{CDM} = 1 x 10^{15}Msun of Cold DM: the bullet subhalo can move with V_{DM}=3000km/s, and the "bullet" X-ray gas can move with V_{gas}=4200km/s. These are nearly the {\it maximum speeds} that are accelerable by the gravity of two truncated CDM halos in a Hubble time even without the ram pressure. Consistency breaks down if one adopts higher end of the error bars for the bullet gas speed (5000-5400km/s), and the bullet gas would not be bound by the sub-cluster halo for the Hubble time. Models with V_{DM}~ 4500km/s ~ V_{gas} would invoke unrealistic large amount M_{CDM}=7x 10^{15}Msun of CDM for a cluster containing only ~ 10^{14}Msun of gas. Our results are generalisable beyond General Relativity, e.g., a speed of $4500\kms$ is easily obtained in the relativistic MONDian lensing model of Angus et al. (2007). However, MONDian model with little hot dark matter $M_{HDM} \le 0.6\times 10^{15}\msun$ and CDM model with a small halo mass $\le 1\times 10^{15}\msun$ are barely consistent with lensing and velocity data.

2007-05-23

0704.0101

Paolo Di Vecchia pdv

Paolo Di Vecchia

The birth of string theory

Latex 60 pages, 2 figures, uses svmult.cls. Contribution to the volume "String theory and fundamental interactions", dedicated to Gabriele Veneziano on his 65th birthday.

Lect.NotesPhys.737:59-118,2008

NORDITA-2007-13

hep-th

In this contribution we go through the developments that in the years 1968 to 1974 led from the Veneziano model to the bosonic string.

2008-11-26

0704.0117

Mang Feng

T. Liu, K.L. Wang, and M. Feng

Lower ground state due to counter-rotating wave interaction in trapped ion system

Complete solution of a trapped ion in both strong and weak excitation regimes and beyond Lamb-Dicke limit. Also applicable to JC model relevant problems

10.1088/0953-4075/40/11/002

quant-ph

We consider a single ion confined in a trap under radiation of two traveling waves of lasers. In the strong-excitation regime and without the restriction of Lamb-Dicke limit, the Hamiltonian of the system is similar to a driving Jaynes-Cummings model without rotating wave approximation (RWA). The approach we developed enables us to present a complete eigensolutions, which makes it available to compare with the solutions under the RWA. We find that, the ground state in our non-RWA solution is energically lower than the counterpart under the RWA. If we have the ion in the ground state, it is equivalent to a spin dependent force on the trapped ion. Discussion is made for the difference between the solutions with and without the RWA, and for the relevant experimental test, as well as for the possible application in quantum information processing.

2009-11-13

0704.0121

Changhyun Ahn

Changhyun Ahn

Meta-Stable Brane Configuration of Product Gauge Groups

27 pp; 7 figures; Pages 8, 17 and 18 improved and figure 7 corrected; the abstract and introduction improved and to appear in CQG

Class.Quant.Grav.25:075001,2008

10.1088/0264-9381/25/7/075001

hep-th

Starting from the N=1 SU(N_c) x SU(N_c') gauge theory with fundamental and bifundamental flavors, we apply the Seiberg dual to the first gauge group and obtain the N=1 dual gauge theory with dual matters including the gauge singlets. By analyzing the F-term equations of the superpotential, we describe the intersecting type IIA brane configuration for the meta-stable nonsupersymmetric vacua of this gauge theory. By introducing an orientifold 6-plane, we generalize to the case for N=1 SU(N_c) x SO(N_c') gauge theory with fundamental and bifundamental flavors. Finally, the N=1 SU(N_c) x Sp(N_c') gauge theory with matters is also described very briefly.

2008-11-26

0704.0128

Kim Page

P.A. Evans (1), A.P. Beardmore (1), K.L. Page (1), L.G. Tyler (1), J.P. Osborne (1), M.R. Goad (1), P.T. O'Brien (1), L. Vetere (2), J. Racusin (2), D. Morris (2), D.N. Burrows (2), M. Capalbi (3), M. Perri (3), N. Gehrels (4) and P. Romano (5,6) ((1) University of Leicester, (2) Pennsylvania State University, (3) ASI Science Data Center, (4) NASA/Goddard Space Flight Center, (5) INAF-Osservatorio Astronomico di Brera, (6) Universita' degli Studi di Milano)

An online repository of Swift/XRT light curves of GRBs

8 pages, 6 figures, Accepted for publication in A&A

10.1051/0004-6361:20077530

astro-ph

Context. Swift data are revolutionising our understanding of Gamma Ray Bursts. Since bursts fade rapidly, it is desirable to create and disseminate accurate light curves rapidly. Aims. To provide the community with an online repository of X-ray light curves obtained with Swift. The light curves should be of the quality expected of published data, but automatically created and updated so as to be self-consistent and rapidly available. Methods. We have produced a suite of programs which automatically generates Swift/XRT light curves of GRBs. Effects of the damage to the CCD, automatic readout-mode switching and pile-up are appropriately handled, and the data are binned with variable bin durations, as necessary for a fading source. Results. The light curve repository website (http://www.swift.ac.uk/xrt_curves) contains light curves, hardness ratios and deep images for every GRB which Swift's XRT has observed. When new GRBs are detected, light curves are created and updated within minutes of the data arriving at the UK Swift Science Data Centre.

2009-11-13

0704.0133

Dieter Lutz

D. Lutz, E. Sturm, L.J. Tacconi, E. Valiante, M. Schweitzer, H. Netzer, R. Maiolino, P. Andreani, O. Shemmer, S. Veilleux

PAH emission and star formation in the host of the z~2.56 Cloverleaf QSO

Accepted for publication as an ApJ Letter. 14 pages, 3 figures.

10.1086/518537

astro-ph

We report the first detection of the 6.2micron and 7.7micron infrared `PAH' emission features in the spectrum of a high redshift QSO, from the Spitzer-IRS spectrum of the Cloverleaf lensed QSO (H1413+117, z~2.56). The ratio of PAH features and rest frame far-infrared emission is the same as in lower luminosity star forming ultraluminous infrared galaxies and in local PG QSOs, supporting a predominantly starburst nature of the Cloverleaf's huge far-infrared luminosity (5.4E12 Lsun, corrected for lensing). The Cloverleaf's period of dominant QSO activity (Lbol ~ 7E13 Lsun) is coincident with an intense (star formation rate ~1000 Msun/yr) and short (gas exhaustion time ~3E7yr) star forming event.

2009-11-13

0704.0135

Nicolas Menicucci

Nicolas C. Menicucci and G. J. Milburn

A Single Trapped Ion as a Time-Dependent Harmonic Oscillator

5 pages (two-column format), no figures, added introductory material, other minor content revisions

Phys. Rev. A 76, 052105 (2007)

10.1103/PhysRevA.76.052105

quant-ph

We show how a single trapped ion may be used to test a variety of important physical models realized as time-dependent harmonic oscillators. The ion itself functions as its own motional detector through laser-induced electronic transitions. Alsing et al. [Phys. Rev. Lett. 94, 220401 (2005)] proposed that an exponentially decaying trap frequency could be used to simulate (thermal) Gibbons-Hawking radiation in an expanding universe, but the Hamiltonian used was incorrect. We apply our general solution to this experimental proposal, correcting the result for a single ion and showing that while the actual spectrum is different from the Gibbons-Hawking case, it nevertheless shares an important experimental signature with this result.

2007-12-23

0704.0137

Suresh Tiwari dr

S C Tiwari

Topological defects, geometric phases, and the angular momentum of light

No figures

Optik-International Journal for Light and Electron Optics, 120, 414-417 (2009)

quant-ph

Recent reports on the intriguing features of vector vortex bearing beams are analyzed using geometric phases in optics. It is argued that the spin redirection phase induced circular birefringence is the origin of topological phase singularities arising in the inhomogeneous polarization patterns. A unified picture of recent results is presented based on this proposition. Angular momentum shift within the light beam (OAM) has exact equivalence with the angular momentum holonomy associated with the geometric phase consistent with our conjecture.

2009-05-15

0704.0139

Barbara Lanzoni

B. Lanzoni (1,2), E. Dalessandro (1,2), F.R. Ferraro (1), C. Mancini (3), G. Beccari (2,4,5), R.T. Rood (6), M. Mapelli (7), S. Sigurdsson (8) (1 Dip. Astro., Bologna; 2 INAF--Oss. Astro., Bologna, 3 Dip. Astro. e Scienza dello Spazio, Firenze; 4 Dip. di Scienze della Comunicazione, Teramo; 5 INAF--Oss. Astro. di Collurania, Teramo; 6 Dep. of Astronomy and Astrophysics, The Pennsylvania State University; 7 S.I.S.S.A., Via Beirut 2 - 4, Trieste; 8 Astronomy Department, University of Virginia)

The Blue Straggler Population of the Globular Cluster M5

ApJ accepted

Astrophys.J.663:267-276,2007

10.1086/518592

astro-ph

By combining high-resolution HST and wide-field ground based observations, in ultraviolet and optical bands, we study the Blue Stragglers Star (BSS) population of the galactic globular cluster M5 (NGC 5904) from its very central regions up to its periphery. The BSS distribution is highly peaked in the cluster center, decreases at intermediate radii and rises again outward. Such a bimodal distribution is similar to those previously observed in other globular clusters (M3, 47Tucanae, NGC6752). As for these clusters, dynamical simulations suggest that, while the majority of BSS in M5 could be originated by stellar collisions, a significant fraction (20-40%) of BSS generated by mass transfer processes in primordial binaries is required to reproduce the observed radial distribution. A candidate BSS has been detected beyond the cluster tidal radius. If confirmed, this could represent an interesting case of an "evaporating" BSS.

2009-06-23

0704.0140

Mariano Cadoni

Mariano Cadoni

Entanglement entropy of two-dimensional Anti-de Sitter black holes

6 pages, 2 figures, typos corrected

Phys.Lett.B653:434-438,2007

10.1016/j.physletb.2007.08.026

hep-th

Using the AdS/CFT correspondence we derive a formula for the entanglement entropy of the anti-de Sitter black hole in two spacetime dimensions. The leading term in the large black hole mass expansion of our formula reproduces exactly the Bekenstein-Hawking entropy S_{BH}, whereas the subleading term behaves as ln S_{BH}. This subleading term has the universal form typical for the entanglement entropy of physical systems described by effective conformal fields theories (e.g. one-dimensional statistical models at the critical point). The well-known form of the entanglement entropy for a two-dimensional conformal field theory is obtained as analytic continuation of our result and is related with the entanglement entropy of a black hole with negative mass.

2008-11-26

0704.0141

Serguei Molodtsov

S.V. Molodtsov, G.M. Zinovjev

Towards self-consistent definition of instanton liquid parameters

11 pages, 4 figures

JHEP 0812:112,2008

10.1088/1126-6708/2008/12/112

hep-ph

The possibility of self-consistent determination of instanton liquid parameters is discussed together with the definition of optimal pseudo-particle configurations and comparing the various pseudo-particle ensembles. The weakening of repulsive interactions between pseudo-particles is argued and estimated.

2009-01-09

0704.0143

Serguei Molodtsov

S.V. Molodtsov, G.M. Zinovjev

Instanton Liquid at Finite Temperature and Chemical Potential of Quarks

9 pages, 2 figures

Phys.Part.Nucl.Lett.4:11-17,2007; PismaFiz.Elem.Chast.Atom.Yadra2007N1:25-35,2007

10.1134/S1547477107010037

hep-ph

Instanton liquid in heated and strongly interacting matter is studied using the variational principle. The dependence of the instanton liquid density (gluon condensate) on the temperature and the quark chemical potential is determined under the assumption that, at finite temperatures, the dominant contribution is given by an ensemble of calorons. The respective one-loop effective quark Lagrangian is used.

2008-11-26

0704.0155

Floris van der Tak

Floris van der Tak (SRON Groningen), John Black (Onsala), Fredrik Schoeier (Stockholm), David Jansen and Ewine van Dishoeck (Leiden)

A computer program for fast non-LTE analysis of interstellar line spectra

Accepted by A&A; 18 A4 pages, 11 figures

10.1051/0004-6361:20066820

astro-ph

The large quantity and high quality of modern radio and infrared line observations require efficient modeling techniques to infer physical and chemical parameters such as temperature, density, and molecular abundances. We present a computer program to calculate the intensities of atomic and molecular lines produced in a uniform medium, based on statistical equilibrium calculations involving collisional and radiative processes and including radiation from background sources. Optical depth effects are treated with an escape probability method. The program is available on the World Wide Web at http://www.sron.rug.nl/~vdtak/radex/index.shtml . The program makes use of molecular data files maintained in the Leiden Atomic and Molecular Database (LAMDA), which will continue to be improved and expanded. The performance of the program is compared with more approximate and with more sophisticated methods. An Appendix provides diagnostic plots to estimate physical parameters from line intensity ratios of commonly observed molecules. This program should form an important tool in analyzing observations from current and future radio and infrared telescopes.

2015-05-13

0704.0156

Han He

Han He, Huaning Wang

Nonlinear force-free coronal magnetic field extrapolation scheme based on the direct boundary integral formulation

This paper has been withdrawn by the authors. This paper has been accepted for publication in JGR-Space Physics. The latest and complete version of the papaer can be downloaded from http://rwcc.bao.ac.cn:8001/swap/NLFFF_DBIE_code/HeHan_NLFFF_JGR.pdf (3.76 MB pdf file)

10.1029/2007JA012441

astro-ph

This paper has been withdrawn by the authors.

2015-05-13

0704.0160

Grazyna Stasinska

G. Stasinska, G. Tenorio-Tagle, M. Rodriguez, W. J. Henney

Oxygen-rich droplets and the enrichment of the ISM

4 pages, 5 colour figures, to be published in the proceedings of the conference "The Metal-Rich Universe", Cambridge University Press

astro-ph

We argue that the discrepancies observed in HII regions between abundances derived from optical recombination lines (ORLs) and collisionally excited lines (CELs) might well be the signature of a scenario of the enrichment of the interstellar medium (ISM) proposed by Tenorio-Tagle (1996). In this scenario, the fresh oxygen released during massive supernova explosions is confined within the hot superbubbles as long as supernovae continue to explode. Only after the last massive supernova explosion, the metal-rich gas starts cooling down and falls on the galaxy within metal-rich droplets. Full mixing of these metal-rich droplets and the ISM occurs during photoionization by the next generations of massive stars. During this process, the metal-rich droplets give rise to strong recombination lines of the metals, leading to the observed ORL-CEL discrepancy. (The full version of this work is submitted to Astronomy and Astrophysics.)

2007-05-23

0704.0166

I\~naki Garc\'ia-Etxebarria

Inaki Garcia-Etxebarria, Fouad Saad, Angel M. Uranga

Supersymmetry breaking metastable vacua in runaway quiver gauge theories

26 pages + appendices, 25 figures. v2: Added some acknowledgments

JHEP 0705:047,2007

10.1088/1126-6708/2007/05/047

IFT-UAM/CSIC-07-14, CERN-PH-TH/2007-063

hep-th

In this paper we consider quiver gauge theories with fractional branes whose infrared dynamics removes the classical supersymmetric vacua (DSB branes). We show that addition of flavors to these theories (via additional non-compact branes) leads to local meta-stable supersymmetry breaking minima, closely related to those of SQCD with massive flavors. We simplify the study of the one-loop lifting of the accidental classical flat directions by direct computation of the pseudomoduli masses via Feynman diagrams. This new approach allows to obtain analytic results for all these theories. This work extends the results for the $dP_1$ theory in hep-th/0607218. The new approach allows to generalize the computation to general examples of DSB branes, and for arbitrary values of the superpotential couplings.

2009-11-13

0704.0167

Jan O. Eeg

Jan O. Eeg

Low Energy Aspects of Heavy Meson Decays

10 pages, 10 figures. Presented at the final Euridice meeting in Kazimierz, Poland 24-27th of august 2006

ActaPhys.Polon.B38:2869-2878,2007

hep-ph

I discuss low energy aspects of heavy meson decays, where there is at least one heavy meson in the final state. Examples are $B -\bar{B}$ mixing, $B \to D \bar{D}$, $B \to D \eta'$, and $B \to D \gamma$. %and $B \to D W $ (Isgur-Wise function). The analysis is performed in the heavy quark limit within heavy-light chiral perturbation theory. Coefficients of $1/N_c$ suppressed chiral Lagrangian terms (beyond factorization) have been estimated by means of a heavy-light chiral quark model.

2008-11-26

0704.0168

Paul Dempsey

Paul Dempsey and Peter Duffy

Radiative losses and cut-offs of energetic particles at relativistic shocks

10 pages, 23 figures and 2 tables. Accepted for publication by MNRAS.

Mon.Not.Roy.Astron.Soc.378:625-634,2007

10.1111/j.1365-2966.2007.11800.x

astro-ph

We investigate the acceleration and simultaneous radiative losses of electrons in the vicinity of relativistic shocks. Particles undergo pitch angle diffusion, gaining energy as they cross the shock by the Fermi mechanism and also emitting synchrotron radiation in the ambient magnetic field. A semi-analytic approach is developed which allows us to consider the behaviour of the shape of the spectral cut-off and the variation of that cut-off with the particle pitch angle. The implications for the synchrotron emission of relativistic jets, such as those in gamma ray burst sources and blazars, are discussed.

2009-06-23

0704.0169

Giorgio Calucci

Giorgio Calucci

Very strong and slowly varying magnetic fields as source of axions

8 pages, no figures

Phys.Rev.D75:097303,2007

10.1103/PhysRevD.75.097303

hep-ph

The investigation on the production of particles in slowly varying but extremely intense magnetic field in extended to the case of axions. The motivation is, as for some previously considered cases, the possibility that such kind of magnetic field may exist around very compact astrophysical objects.

2008-11-26

0704.0171

Jim Hinton

F. Aharonian, et al

Discovery of a point-like very-high-energy gamma-ray source in Monoceros

5 pages, 4 figures, to appear in A&A

10.1051/0004-6361:20077299

astro-ph

The complex Monoceros Loop SNR/Rosette Nebula region contains several potential sources of very-high-energy (VHE) gamma-ray emission and two as yet unidentified high-energy EGRET sources. Sensitive VHE observations are required to probe acceleration processes in this region. The H.E.S.S. telescope array has been used to search for very high-energy gamma-ray sources in this region. CO data from the NANTEN telescope were used to map the molecular clouds in the region, which could act as target material for gamma-ray production via hadronic interactions. We announce the discovery of a new gamma-ray source, HESS J0632+058, located close to the rim of the Monoceros SNR. This source is unresolved by H.E.S.S. and has no clear counterpart at other wavelengths but is possibly associated with the weak X-ray source 1RXS J063258.3+054857, the Be-star MWC 148 and/or the lower energy gamma-ray source 3EG J0634+0521. No evidence for an associated molecular cloud was found in the CO data.

2009-11-13

0704.0179

Marco Bellini

Alessandro Zavatta, Valentina Parigi, and Marco Bellini

Experimental nonclassicality of single-photon-added thermal light states

7 pages, 6 figures, accepted for publication in Phys. Rev. A

PHYSICAL REVIEW A 75, 052106 (2007)

10.1103/PhysRevA.75.052106

quant-ph

We report the experimental realization and tomographic analysis of novel quantum light states obtained by exciting a classical thermal field by a single photon. Such states, although completely incoherent, possess a tunable degree of quantumness which is here exploited to put to a stringent experimental test some of the criteria proposed for the proof and the measurement of state non-classicality. The quantum character of the states is also given in quantum information terms by evaluating the amount of entanglement that they can produce.

2009-11-13

0704.0184

Paolo Padovani

P. Padovani (ESO)

Gamma-ray emitting AGN and GLAST

5 pages, 1 figure, invited talk at the First GLAST Symposium, February 5-8, 2007, Stanford University, USA, to appear in the proceedings

AIP Conf.Proc.921:19-23,2007

10.1063/1.2757258

astro-ph

I describe the different classes of Active Galactic Nuclei (AGN) and the basic tenets of unified schemes. I then review the properties of the extragalactic sources detected in the GeV and TeV bands, showing that the vast majority of them belong to the very rare blazar class. I further discuss the kind of AGN GLAST is likely to detect, making some predictions going from the obvious to the likely, all the way to the less probable.

2009-06-23

0704.0186

Ryo Takahasi

Ryo Takahashi and Morimitsu Tanimoto

Dark energy and neutrino model in SUSY -- Remarks on active and sterile neutrinos mixing --

12 pages, 7 figures, to appear in the proceedings of International Workshop on Neutrino Masses and Mixings -- Toward Unified Understanding of Quark and Lepton Mass Matrices --, Shizuoka, Japan, 17-19 Dec 2006

Int.J.Mod.Phys.E16:1529-1540,2007

10.1142/S0218301307006861

hep-ph

We consider a Mass Varying Neutrinos (MaVaNs) model in supersymmetric theory. The model includes effects of supersymmetry breaking transmitted by the gravitational interaction from the hidden sector, in which supersymmetry was broken, to the dark energy sector. Then evolutions of the neutrino mass and the equation of state parameter of the dark energy are presented in the model. It is remarked that only the mass of a sterile neutrino is variable in the case of the vanishing mixing between the left-handed and a sterile neutrino on cosmological time scale. The finite mixing makes the mass of the left-handed neutrino variable.

2008-11-26

0704.0187

Gabor Worseck

G. Worseck (1), C. Fechner (2,3), L. Wisotzki (1) and A. Dall'Aglio (1) ((1) Astrophysikalisches Institut Potsdam, (2) Hamburger Sternwarte, (3) Universit\"at Potsdam)

The transverse proximity effect in spectral hardness on the line of sight towards HE 2347-4342

15 pages, 11 figures, accepted by A&A, major revision of Section 5 following the referee's comments

Astron.Astrophys. 473 (2007) 805

10.1051/0004-6361:20077585

astro-ph

We report the discovery of 14 quasars in the vicinity of HE2347-4342, one of the two quasars whose intergalactic HeII forest has been resolved with FUSE. By analysing the HI and the HeII opacity variations separately, no transverse proximity effect is detected near three foreground quasars of HE2347-4342: QSOJ23503-4328 (z=2.282, $\vartheta=3.59$ arcmin), QSOJ23500-4319 (z=2.302, $\vartheta=8.77$ arcmin) and QSOJ23495-4338 (z=2.690, $\vartheta=16.28$ arcmin). This is primarily due to line contamination and overdensities probably created by large-scale structure. By comparing the HI absorption and the corresponding HeII absorption, we estimated the fluctuating spectral shape of the extragalactic UV radiation field along this line of sight. We find that the UV spectral shape near HE2347-4342 and in the projected vicinity of the three foreground quasars is statistically harder than expected from UV background models dominated by quasars. In addition, we find three highly ionised metal line systems near the quasars. However, they do not yield further constraints on the shape of the ionising field. We conclude that the foreground quasars show a transverse proximity effect that is detectable as a local hardening of the UV radiation field, although the evidence is strongest for QSOJ23495-4338. Thus, the relative spectral hardness traces the proximity effect also in overdense regions prohibiting the traditional detection in the HI forest. Furthermore, we emphasise that softening of quasar radiation by radiative transfer in the intergalactic medium is important to understand the observed spectral shape variations. From the transverse proximity effect of QSOJ23495-4338 we obtain a lower limit on the quasar lifetime of ~25 Myr.

2011-11-09

0704.0192

Karen O'Neil

K. O'Neil, S. Oey, G. Bothun

Star Formation in Galaxies with Large Lower Surface Brightness Disks

50 pages; Full paper with all figures available at http://www.gb.nrao.edu/~koneil; Accepted by AJ

10.1086/518831

astro-ph

We present B, R, and Halpha imaging data of 19 large disk galaxies whose properties are intermediate between classical low surface brightness galaxies and ordinary high surface brightness galaxies. We use data taken from the Lowell 1.8m Perkins telescope to determine the galaxies' overall morphology, color, and star formation properties. Morphologically, the galaxies range from Sb through Irr and include galaxies with and without nuclear bars. The colors of the galaxies vary from B-R = 0.3 - 1.9, and most show at least a slight bluing of the colors with increasing radius. The Halpha images of these galaxies show an average star formation rate lower than is found for similar samples with higher surface brightness disks. Additionally, the galaxies studied have both higher gas mass-to-luminosity and diffuse Halpha emission than is found in higher surface brightness samples.

2009-11-13

0704.0196

Michal Praszalowicz

Karolina Piesciuk, Michal Praszalowicz

Remarks on N_c dependence of decays of exotic baryons

8 pages, 6 figures to be published in proceedings of YKIS06 in Progress of Theoretical Physics. In v2 minor typos corrected

Prog.Theor.Phys.Suppl.168:70-77,2007

10.1143/PTPS.168.70

TPJU-03/2007

hep-ph

We calculate the N_c dependence of the decay widths of exotic eikosiheptaplet within the framework of Chral Quark Soliton Model. We also discuss generalizations of regular baryon representations for arbitrary N_c.

2008-11-26

0704.0202

Simon Perdrix

Simon Perdrix

Towards Minimal Resources of Measurement-based Quantum Computation

8 pages

New J. Phys. 9 206 (2007)

10.1088/1367-2630/9/6/206

quant-ph

We improve the upper bound on the minimal resources required for measurement-based quantum computation. Minimizing the resources required for this model is a key issue for experimental realization of a quantum computer based on projective measurements. This new upper bound allows also to reply in the negative to the open question about the existence of a trade-off between observable and ancillary qubits in measurement-based quantum computation.

2007-09-20

0704.0203

August Muench

August A. Muench, Charles J. Lada, K. L. Luhman, James Muzerolle and Erick Young

A Spitzer census of the IC 348 nebula

Accepted to AJ; 33 pages in emulateapj format.

Astron.J.134:411-444,2007

10.1086/518560

astro-ph

We present a Spitzer based census of the IC 348 nebula and embedded star cluster. Our Spitzer census supplemented by ground based spectra has added 42 class II T-Tauri sources to the cluster membership and identified ~20 class 0/I protostars. The population of IC 348 likely exceeds 400 sources after accounting statistically for unidentified diskless members. Our Spitzer census of IC 348 reveals a population of protostars that is anti-correlated spatially with the T-Tauri members, which comprise the centrally condensed cluster around a B star. The protostars are instead found mostly at the cluster periphery about 1 pc from the B star and spread out along a filamentary ridge. We find that the star formation rate in this protostellar ridge is consistent with that rate which built the exposed cluster while the presence of fifteen cold, starless, millimeter cores intermingled with this protostellar population indicates that the IC 348 nebula has yet to finish forming stars. We show that the IC 348 cluster is of order 3-5 crossing times old, and, as evidenced by its smooth radial profile and confirmed mass segregation, is likely relaxed. While it seems apparent that the current cluster configuration is the result of dynamical evolution and its primordial structure has been erased, our findings support a model where embedded clusters are built up from numerous smaller sub-clusters. Finally, the results of our Spitzer census indicate that the supposition that star formation must progress rapidly in a dark cloud should not preclude these observations that show it can be relatively long lived.

2009-06-23

0704.0205

Paolo Esposito

P. Esposito, A. Tiengo, A. De Luca, F. Mattana

Discovery of X-ray emission from the young radio pulsar PSR J1357-6429

Revised version (minor changes in text and figures). Accepted for publication on Astronomy and Astrophysics Letters on 10/04/2007

Astronomy and Astrophysics, Volume 467, Issue 2, May IV 2007, pp.L45-L48

10.1051/0004-6361:20077480

astro-ph

We present the first X-ray detection of the very young pulsar PSR J1357-6429 (characteristic age of 7.3 kyr) using data from the XMM-Newton and Chandra satellites. We find that the spectrum is well described by a power-law plus blackbody model, with photon index Gamma=1.4 and blackbody temperature kT=160 eV. For the estimated distance of 2.5 kpc, this corresponds to a 2-10 keV luminosity of about 1.2E+32 erg/s, thus the fraction of the spin-down energy channeled by PSR J1357-6429 into X-ray emission is one of the lowest observed. The Chandra data confirm the positional coincidence with the radio pulsar and allow to set an upper limit of 3E+31 erg/s on the 2-10 keV luminosity of a compact pulsar wind nebula. We do not detect any pulsed emission from the source and determine an upper limit of 30% for the modulation amplitude of the X-ray emission at the radio frequency of the pulsar.

2009-02-23

0704.0209

Sangwook Park

Sangwook Park, David N. Burrows, Gordon P. Garmire (Penn State), Richard McCray (Colorado), Judith L. Racusin (Penn State), Svetozar A. Zhekov (Space Res Inst)

Chandra Observations of Supernova 1987A

8 pages, 4 figures (including 2 color figs), 3 tables. To appear in the proceedings of "Supernova 1987A: 20 Years after Supernovae and Gamma-Ray Bursters", held in Aspen CO. USA, Feb 19-23, 2007

AIP Conf.Proc.937:43-50,2007

10.1063/1.2803606

astro-ph

We have been monitoring Supernova (SN) 1987A with {\it Chandra X-Ray Observatory} since 1999. We present a review of previous results from our {\it Chandra} observations, and some preliminary results from new {\it Chandra} data obtained in 2006 and 2007. High resolution imaging and spectroscopic studies of SN 1987A with {\it Chandra} reveal that X-ray emission of SN 1987A originates from the hot gas heated by interaction of the blast wave with the ring-like dense circumstellar medium (CSM) that was produced by the massive progenitor's equatorial stellar winds before the SN explosion. The blast wave is now sweeping through dense CSM all around the inner ring, and thus SN 1987A is rapidly brightening in soft X-rays. At the age of 20 yr (as of 2007 January), X-ray luminosity of SN 1987A is $L_{\rm X}$ $\sim$ 2.4 $\times$ 10$^{36}$ ergs s$^{-1}$ in the 0.5$-$10 keV band. X-ray emission is described by two-component plane shock model with electron temperatures of $kT$ $\sim$ 0.3 and 2 keV. As the shock front interacts with dense CSM all around the inner ring, the X-ray remnant is now expanding at a much slower rate of $v$ $\sim$ 1400 km s$^{-1}$ than it was until 2004 ($v$ $\sim$ 6000 km s$^{-1}$).

2009-06-23

0704.0219

Joseph Gelfand

Joseph D. Gelfand, B. M. Gaensler, Patrick O. Slane, Daniel J. Patnaude, John P. Hughes, Fernando Camilo

The Radio Emission, X-ray Emission, and Hydrodynamics of G328.4+0.2: A Comprehensive Analysis of a Luminous Pulsar Wind Nebula, its Neutron Star, and the Progenitor Supernova Explosion

27 pages, 11 figures, accepted for publication in The Astrophysical Journal

Astrophys.J.663:468-486,2007

10.1086/518498

astro-ph

We present new observational results obtained for the Galactic non-thermal radio source G328.4+0.2 to determine both if this source is a pulsar wind nebula or supernova remnant, and in either case, the physical properties of this source. Using X-ray data obtained by XMM, we confirm that the X-ray emission from this source is heavily absorbed and has a spectrum best fit by a power law model of photon index=2 with no evidence for a thermal component, the X-ray emission from G328.4+0.2 comes from a region significantly smaller than the radio emission, and that the X-ray and radio emission are significantly offset from each other. We also present the results of a new high resolution (7 arcseconds) 1.4 GHz image of G328.4+0.2 obtained using the Australia Telescope Compact Array, and a deep search for radio pulsations using the Parkes Radio Telescope. We find that the radio emission has a flat spectrum, though some areas along the eastern edge of G328.4+0.2 have a steeper radio spectral index of ~-0.3. Additionally, we obtain a luminosity limit of the central pulsar of L_{1400} < 30 mJy kpc^2, assuming a distance of 17 kpc. In light of these observational results, we test if G328.4+0.2 is a pulsar wind nebula (PWN) or a large PWN inside a supernova remnant (SNR) using a simple hydrodynamic model for the evolution of a PWN inside a SNR. As a result of this analysis, we conclude that G328.4+0.2 is a young (< 10000 years old) pulsar wind nebula formed by a low magnetic field (<10^12 G) neutron star born spinning rapidly (<10 ms) expanding into an undetected SNR formed by an energetic (>10^51 ergs), low ejecta mass (M < 5 Solar Masses) supernova explosion which occurred in a low density (n~0.03 cm^{-3}) environment.

2009-06-23

0704.0222

Miguel \'Angel S\'anchez-Conde Mr.

Miguel A. Sanchez-Conde

Dark Matter annihilation in Draco: new considerations on the expected gamma flux

2 pages, 2 figures, to appear in the Proceedings of the First International GLAST Symposium, Stanford University, 5-8 February 2007

AIP Conf.Proc.921:510-511,2007

10.1063/1.2757426

astro-ph

A new estimation of the gamma-ray flux that we expect to detect from SUSY dark matter annihilation from the Draco dSph is presented using the DM density profiles compatible with the latest observations. This calculation takes also into account the important effect of the Point Spread Function (PSF) of the telescope. We show that this effect is crucial in the way we will observe and interpret a possible signal detection. Finally, we discuss the prospects to detect a possible gamma signal from Draco for MAGIC and GLAST.

2009-06-23

0704.0223

Fu-Yan Bian

Yu-Qing Lou (1,2,3) and Wei-Gang Wang (1), ((1) Tsinghua Center For astrophysics, Tsinghua University, (2)The University of Chicago, (3) National Astronomical Observatories, Chinese Academy of Science.)

Magnetohydrodynamic Rebound Shocks of Supernovae

5 pages, 1 figure, Accepted for publication in MNRAS

Mon.Not.Roy.Astron.Soc.Lett.378:L54-L58,2007

10.1111/j.1745-3933.2007.00319.x

astro-ph

We construct magnetohydrodynamic (MHD) similarity rebound shocks joining `quasi-static' asymptotic solutions around the central degenerate core to explore an MHD model for the evolution of random magnetic field in supernova explosions. This provides a theoretical basis for further studying synchrotron diagnostics, MHD shock acceleration of cosmic rays, and the nature of intense magnetic field in compact objects. The magnetic field strength in space approaches a limiting ratio, that is comparable to the ratio of the ejecta mass driven out versus the progenitor mass, during this self-similar rebound MHD shock evolution. The intense magnetic field of the remnant compact star as compared to that of the progenitor star is mainly attributed to both the gravitational core collapse and the radial distribution of magnetic field.

2009-06-23

0704.0225

Alexander Kashlinsky

A. Kashlinsky and D. Band

Exploring First Stars Era with GLAST

to appear in Proceedings of 1st International GLAST Symposium

AIP Conf.Proc.921:243-245,2007

10.1063/1.2757312

astro-ph

Cosmic infrared background (CIB) includes emissions from objects inaccessible to current telescopic studies, such as the putative Population III, the first stars. Recently, strong direct evidence for significant CIB levels produced by the first stars came from CIB fluctuations discovered in deep Spitzer images. Such CIB levels should have left a unique absorption feature in the spectra of high-z GRBs and blazars as suggested in [4]. This is observable with GLAST sources at z>2 and measuring this absorption will give important information on energetics and constituents of the first stars era.

2009-06-23

0704.0226

Francesco Tombesi

F. Tombesi (1,2), B. De Marco (3), K. Iwasawa (4), M. Cappi (1), M. Dadina (1), G. Ponti (1,2), G. Miniutti (5) and G.G.C. Palumbo (2) ((1) INAF-IASF Bologna, (2) UNIBO, (3) SISSA, (4) MPE, (5) Institute of Astronomy, Cambridge)

Correlated modulation between the redshifted Fe K alpha line and the continuum emission in NGC 3783

8 pages, 7 figures, to be published in Astronomy and Astrophysics

10.1051/0004-6361:20066713

astro-ph

It has been suggested that X-ray observations of rapidly variable Seyfert galaxies may hold the key to probe the gas orbital motions in the innermost regions of accretion discs around black holes and, thus, trace flow patterns under the effect of the hole strong gravitational field. We explore this possibility analizing XMM-Newton observations of the seyfert 1 galaxy NGC 3783. A detiled time-resolved spectral analysis is performed down to the shortest possible time-scales (few ks) using "excess maps" and cross-correlating light curves in different energy bands. In addition to a constant core of the Fe K alpha line, we detected a variable and redshifted Fe K alpha emission feature between 5.3-6.1 keV. The line exhibits a modulation on a time-scale of 27 ks that is similar to and in phase with a modulation of the 0.3-10 keV source continuum. The time-scale of the correlated variability of the redshifted Fe line and continuum agrees with the local dynamical time-scale of the accretion disc at 10 r_g around a black hole of 10^7 M_sun. Given the shape of the redshfted line emission and the overall X-ray variability pattern, the line is likely to arise from the relativistic region near the black hole.

2009-11-13

0704.0230

Rene Duffard

R. Duffard and F. Roig

Two new basaltic asteroids in the Outer Main Belt?

13 pages, 3 figures, 2 tables

astro-ph

The identification of basaltic asteroids in the asteroid Main Belt and the description of their surface mineralogy is necessary to understand the diversity in the collection of basaltic meteorites. Basaltic asteroids can be identified from their visible reflectance spectra and are classified as V-type in the usual taxonomies. In this work, we report visible spectroscopic observations of two candidate V-type asteroids, (7472) Kumakiri and (10537) 1991 RY16, located in the outer Main Belt (a > 2.85 UA). These candidate have been previously identified by Roig and Gil-Hutton (2006, Icarus 183, 411) using the Sloan Digital Sky Survey colors. The spectroscopic observations have been obtained at the Calar Alto Observatory, Spain, during observational runs in November and December 2006. The spectra of these two asteroids show the steep slope shortwards of 0.70 microns and the deep absorption feature longwards of 0.75 microns that are characteristic of V-type asteroids. However, the presence of a shallow but conspicuous absorption band around 0.65 microns opens some questions about the actual mineralogy of these two asteroids. Such band has never been observed before in basaltic asteroids with the intensity we detected it. We discuss the possibility for this shallow absorption feature to be caused by the presence of chromium on the asteroid surface. Our results indicate that, together with (1459) Magnya, asteroids (7472) Kumakiri and (10537) 1991 RY16 may be the only traces of basaltic material found up to now in the outer Main Belt.

2008-01-14

0704.0232

Christoph Bergbauer

Christoph Bergbauer, Dirk Kreimer

New algebraic aspects of perturbative and non-perturbative Quantum Field Theory

15 pages, Contribution to the Proceedings of the ICMP 2006, 2 typos corrected, final version

in "New Trends in Mathematical Physics; Selected contributions of the XVth International Congress on Mathematical Physics", V. Sidoravicius (Ed.), Springer (2009)

hep-th

http://arxiv.org/licenses/nonexclusive-distrib/1.0/

In this expository article we review recent advances in our understanding of the combinatorial and algebraic structure of perturbation theory in terms of Feynman graphs, and Dyson-Schwinger equations. Starting from Lie and Hopf algebras of Feynman graphs, perturbative renormalization is rephrased algebraically. The Hochschild cohomology of these Hopf algebras leads the way to Slavnov-Taylor identities and Dyson-Schwinger equations. We discuss recent progress in solving simple Dyson-Schwinger equations in the high energy sector using the algebraic machinery. Finally there is a short account on a relation to algebraic geometry and number theory: understanding Feynman integrals as periods of mixed (Tate) motives.

2009-11-04

0704.0234

Gabriele Ghisellini

G. Ghirlanda (1), L. Nava (1,2), G. Ghisellini (1), C. Firmani (1,3) ((1) Osserv. Astr. di Brera, (2) Univ. degli Studi dell'Insubria, (3) U.N.A.M.)

Comments on ``Are Swift Gamma-Ray Bursts consistent with the Ghirlanda relation?", by Campana et al.(astro--ph/0703676)

3 pages

astro-ph

In their recent paper, Campana et al. (2007) found that 5 bursts, among those detected by Swift, are outliers with respect to the E_peak-E_gamma ("Ghirlanda") correlation. We instead argue that they are not.

2007-05-23

0704.0237

Christopher W. Mauche

Christopher W. Mauche, Duane A. Liedahl, Shizuka Akiyama (Lawrence Livermore Nat'l Lab.), Tomasz Plewa (University of Chicago)

Hydrodynamic and Spectral Simulations of HMXB Winds

4 pages including 2 color encapsulated postscript figures; LaTeX format, uses ptptex.cls; submitted for inclusion in the proceedings of "The Extreme Universe in the Suzaku Era" conference, to be published in Progress of Theoretical Physics, Supplement.

Prog.Theor.Phys.Suppl.169:196-199,2007

10.1143/PTPS.169.196

astro-ph

We describe preliminary results of a global model of the radiatively-driven photoionized wind and accretion flow of the high-mass X-ray binary Vela X-1. The full model combines FLASH hydrodynamic calculations, XSTAR photoionization calculations, HULLAC atomic data, and Monte Carlo radiation transport. We present maps of the density, temperature, velocity, and ionization parameter from a FLASH two-dimensional time-dependent simulation of Vela X-1, as well as maps of the emissivity distributions of the X-ray emission lines.

2009-06-23

0704.0238

Geoffrey C. Bower

Geoffrey C. Bower (Berkeley), Alberto Bolatto (Berkeley), Eric Ford (CfA, Florida), Paul Kalas (Berkeley), Jim Ulvestad (NRAO)

Radio Astrometric Detection and Characterization of Extra-Solar Planets: A White Paper Submitted to the NSF ExoPlanet Task Force

astro-ph

The extraordinary astrometric accuracy of radio interferometry creates an important and unique opportunity for the discovery and characterization of exo-planets. Currently, the Very Long Baseline Array can routinely achieve better than 100 microarcsecond accuracy, and can approach 10 microarcsecond with careful calibration. We describe here RIPL, the Radio Interferometric PLanet search, a new program with the VLBA and the Green Bank 100 m telescope that will survey 29 low-mass, active stars over 3 years with sub-Jovian planet mass sensitivity at 1 AU. An upgrade of the VLBA bandwidth will increase astrometric accuracy by an order of magnitude. Ultimately, the colossal collecting area of the Square Kilometer Array could push astrometric accuracy to 1 microarcsecond, making detection and characterizaiton of Earth mass planets possible. RIPL and other future radio astrometric planet searches occupy a unique volume in planet discovery and characterization parameter space. The parameter space of astrometric searches gives greater sensitivity to planets at large radii than radial velocity searches. For the VLBA and the expanded VLBA, the targets of radio astrometric surveys are by necessity nearby, low-mass, active stars, which cannot be studied efficiently through the radial velocity method, coronagraphy, or optical interferometry. For the SKA, detection sensitivity will extend to solar-type stars. Planets discovered through radio astrometric methods will be suitable for characterization through extreme adaptive optics. The complementarity of radio astrometric techniques with other methods demonstrates that radio astrometry can play an important role in the roadmap for exoplanet discovery and characterization.

2007-05-23

0704.0240

Dam Thanh Son

D. T. Son, A. O. Starinets

Viscosity, Black Holes, and Quantum Field Theory

23 pages, a review. New proof of the universality of the viscosity entropy ratio, new derivation of Kubo's formula; references added and minor typos corrected in version 2

Ann.Rev.Nucl.Part.Sci.57:95-118,2007

10.1146/annurev.nucl.57.090506.123120

INT PUB 07-02

hep-th

We review recent progress in applying the AdS/CFT correspondence to finite-temperature field theory. In particular, we show how the hydrodynamic behavior of field theory is reflected in the low-momentum limit of correlation functions computed through a real-time AdS/CFT prescription, which we formulate. We also show how the hydrodynamic modes in field theory correspond to the low-lying quasinormal modes of the AdS black p-brane metric. We provide a proof of the universality of the viscosity/entropy ratio within a class of theories with gravity duals and formulate a viscosity bound conjecture. Possible implications for real systems are mentioned.

2008-11-26

0704.0242

Vincent L. Fish

Vincent L. Fish (NRAO)

Masers and star formation

10 pages, iaus.cls, to appear in IAU Symp. 242 proceedings (Astrophysical masers and their environments)

10.1017/S1743921307012604

astro-ph

Recent observational and theoretical advances concerning astronomical masers in star forming regions are reviewed. Major masing species are considered individually and in combination. Key results are summarized with emphasis on present science and future prospects.

2009-11-13

0704.0251

Gilad Gour

Gilad Gour, Nolan R. Wallach

Entanglement of Subspaces and Error Correcting Codes

8 pages, Published Version

Phys. Rev. A 76, 042309 (2007)

10.1103/PhysRevA.76.042309

quant-ph

We introduce the notion of entanglement of subspaces as a measure that quantify the entanglement of bipartite states in a randomly selected subspace. We discuss its properties and in particular we show that for maximally entangled subspaces it is additive. Furthermore, we show that maximally entangled subspaces can play an important role in the study of quantum error correction codes. We discuss both degenerate and non-degenerate codes and show that the subspace spanned by the logical codewords of a non-degenerate code is a 2k-totally (maximally) entangled subspace. As for non-degenerate codes, we provide a mathematical definition in terms of subspaces and, as an example, we analyze Shor's nine qubits code in terms of 22 mutually orthogonal subspaces.

2011-11-09

0704.0252

Ashutosh Alok

Ashutosh Kumar Alok and S. Uma Sankar

Does the present data on B_s - bar B_s mixing rule out a large enhancement in the branching ratio of B_s --> mu+ mu- ?

7 pages, no figures

hep-ph

In this letter, we consider the constraints imposed by the recent measurement of B_s - bar B_s mixing on the new physics contribution to the rare decay B_s --> mu+ mu-. New physics in the form vector and axial-vector couplings is already severely constrained by the data on B --> (K,K*) mu+ mu-. Here, we show that B_s - bar B_s mixing data, together with the data on K0 - bar K0 mixing and K_L --> mu+ mu- decay rate, strongly constrain the scalar-pseudoscalar contribution to B_s --> mu+ mu-. We conclude that new physics can at best lead to a factor of 2 increase in the branching ratio of B_s --> mu+ mu- compared to its Standard Model expectation.

2007-05-23

0704.0253

Paul Harvey

Paul M. Harvey, Luisa M. Rebull, Tim Brooke, William J. Spiesman, Nicholas Chapman, Tracy L. Huard, Neal J. Evans II, Lucas Cieza, Shih-Ping Lai, Lori E. Allen, Lee G. Mundy, Deborah L. Padgett, Anneila I. Sargent, Karl R. Stapelfeldt, Philip C. Myers, Ewine F. van Dishoeck, Geoffrey A. Blake, David W. Koerner

The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds VIII. Serpens Observed with MIPS

Astrophys.J.663:1139-1148,2007

10.1086/518647

astro-ph

We present maps of 1.5 square degrees of the Serpens dark cloud at 24, 70, and 160\micron observed with the Spitzer Space Telescope MIPS Camera. More than 2400 compact sources have been extracted at 24um, nearly 100 at 70um, and 4 at 160um. We estimate completeness limits for our 24um survey from Monte Carlo tests with artificial sources inserted into the Spitzer maps. We compare source counts, colors, and magnitudes in the Serpens cloud to two reference data sets, a 0.50 deg^2 set on a low-extinction region near the dark cloud, and a 5.3 deg^2 subset of the SWIRE ELAIS N1 data that was processed through our pipeline. These results show that there is an easily identifiable population of young stellar object candidates in the Serpens Cloud that is not present in either of the reference data sets. We also show a comparison of visual extinction and cool dust emission illustrating a close correlation between the two, and find that the most embedded YSO candidates are located in the areas of highest visual extinction.

2010-03-18

0704.0254

Alexandre Alves

Alexandre Alves and Oscar Eboli

Unravelling the sbottom spin at the CERN LHC

9 pages, 11 figures

Phys.Rev.D75:115013,2007

10.1103/PhysRevD.75.115013

hep-ph

Establishing that a signal of new physics is undoubtly supersymmetric requires not only the discovery of the supersymmetric partners but also probing their spins and couplings. We show that the sbottom spin can be probed at the CERN Large Hadron Collider using only angular correlations in sbottom pair production with subsequent decay of sbottoms into bottom quark plus the lightest neutralino, which allow us to distinguish a universal extra dimensional interpretation with a fermionic heavy bottom quark from supersymmetry with a bosonic bottom squark. We demonstrate that this channel provides a clear indication of the sbottom spin provided the sbottom production rate and branching ratio into bottom quark plus the lightest neutralino are sufficiently large to have a clear signal above Standard Model backgrounds.

2008-11-26

0704.0255

Felipe Marin

Felipe Marin (Chicago, KICP), Risa Wechsler (KIPAC, Stanford), Joshua Frieman (Chicago, KICP and Fermilab), Robert Nichol (ICG, Portsmouth)

Modeling the three-point correlation function

12 pages, 11 figures, ApJ accepted. Corrected typos, minor changes from referee comments

Astrophys.J.672:849-860,2008

10.1086/523628

astro-ph

We present new predictions for the galaxy three-point correlation function (3PCF) using high-resolution dissipationless cosmological simulations of a flat LCDM Universe which resolve galaxy-size halos and subhalos. We create realistic mock galaxy catalogs by assigning luminosities and colors to dark matter halos and subhalos, and we measure the reduced 3PCF as a function of luminosity and color in both real and redshift space. As galaxy luminosity and color are varied, we find small differences in the amplitude and shape dependence of the reduced 3PCF, at a level qualitatively consistent with recent measurements from the SDSS and 2dFGRS. We confirm that discrepancies between previous 3PCF measurements can be explained in part by differences in binning choices. We explore the degree to which a simple local bias model can fit the simulated 3PCF. The agreement between the model predictions and galaxy 3PCF measurements lends further credence to the straightforward association of galaxies with CDM halos and subhalos.

2008-11-26

0704.0256

Paul Harvey

Paul M. Harvey and Andrew Oldag

Multi-spectral Observations of Lunar Occultations: I. Resolving The Dust Shell Around AFGL 5440

Astrophys.J.663:543-552,2007

10.1086/518588

astro-ph

We present observations and modeling of a lunar occultation of the dust-enshrouded carbon star AFGL 5440. The observations were made over a continuous range of wavelengths from 1 - 4um with a high-speed spectrophotometer designed expressly for this purpose. We find that the occultation fringes cannot be fit by any single-size model. We use the DUSTY radiative transfer code to model a circumstellar shell and fit both the observed occultation light curves and the spectral energy distribution described in the literature. We find a strong constraint on the inner radius of the dust shell, Tmax = 950 K +/- 50K, and optical depth at 5um of 0.5 +/- 0.1. The observations are best fit by models with a density gradient of r^-2 or the gradient derived by Ivezic & Elitzur for a radiatively driven hydrodynamic outflow. Our models cannot fit the observed IRAS 60um flux without assuming a substantial abundance of graphite or by assuming a substantially higher mass-loss rate in the past.

2009-11-13

0704.0259

Scott J. Kenyon

Scott J. Kenyon, Benjamin C. Bromley, David P. O'Brien, Donald R. Davis

Formation and Collisional Evolution of Kuiper Belt Objects

23 pages, 9 figures, 1 table; to appear in `Transneptunian Objects', Barucci et al. eds., University of Arizona Press

astro-ph

This chapter summarizes analytic theory and numerical calculations for the formation and collisional evolution of KBOs at 20--150 AU. We describe the main predictions of a baseline self-stirring model and show how dynamical perturbations from a stellar flyby or stirring by a giant planet modify the evolution. Although robust comparisons between observations and theory require better KBO statistics and more comprehensive calculations, the data are broadly consistent with KBO formation in a massive disk followed by substantial collisional grinding and dynamical ejection. However, there are important problems reconciling the results of coagulation and dynamical calculations. Contrasting our current understanding of the evolution of KBOs and asteroids suggests that additional observational constraints, such as the identification of more dynamical families of KBOs (like the 2003 EL61 family), would provide additional information on the relative roles of collisional grinding and dynamical ejection in the Kuiper Belt. The uncertainties also motivate calculations that combine collisional and dynamical evolution, a `unified' calculation that should give us a better picture of KBO formation and evolution.

2007-05-23

0704.0261

Scott Randall

Scott W. Randall, Maxim Markevitch, Douglas Clowe, Anthony H. Gonzalez, and Marusa Bradac

Constraints on the Self-Interaction Cross-Section of Dark Matter from Numerical Simulations of the Merging Galaxy Cluster 1E 0657-5

10.1086/587859

astro-ph

(Abridged) We compare recent results from X-ray, strong lensing, weak lensing, and optical observations with numerical simulations of the merging galaxy cluster 1E0657-56. X-ray observations reveal a bullet-like subcluster with a prominent bow shock, while lensing results show that the positions of the total mass peaks are consistent with the centroids of the collisionless galaxies (and inconsistent with the X-ray brightness peaks). Previous studies, based on older observational datasets, have placed upper limits on the self-interaction cross-section of dark matter per unit mass, sigma/m, using simplified analytic techniques. In this work, we take advantage of new, higher-quality observational datasets by running N-body simulations of 1E0657-56 that include the effects of self-interacting dark matter, and comparing the results with observations. Furthermore, the recent data allow for a new independent method of constraining sigma/m, based on the non-observation of an offset between the bullet subcluster mass peak and galaxy centroid. This new method places an upper limit (68% confidence) of sigma/m < 1.25 cm^2/g. If we make the assumption that the subcluster and the main cluster had equal mass-to-light ratios prior to the merger, we derive our most stringent constraint of sigma/m < 0.7 cm^2/g, which comes from the consistency of the subcluster's observed mass-to-light ratio with the main cluster's, and with the universal cluster value, ruling out the possibility of a large fraction of dark matter particles being scattered away due to collisions. Our limit is a slight improvement over the previous result from analytic estimates, and rules out most of the 0.5 - 5cm^2/g range invoked to explain inconsistencies between the standard collisionless cold dark matter model and observations.

2009-11-13

0704.0262

Matteo Bertolini

Riccardo Argurio, Matteo Bertolini, Gabriele Ferretti, Alberto Lerda and Christoffer Petersson

Stringy Instantons at Orbifold Singularities

Latex, 29 pages, 6 figures. v3: typos corrected, one comment and refs added, published version

JHEP 0706:067,2007

10.1088/1126-6708/2007/06/067

hep-th

We study the effects produced by D-brane instantons on the holomorphic quantities of a D-brane gauge theory at an orbifold singularity. These effects are not limited to reproducing the well known contributions of the gauge theory instantons but also generate extra terms in the superpotential or the prepotential. On these brane instantons there are some neutral fermionic zero-modes in addition to the ones expected from broken supertranslations. They are crucial in correctly reproducing effects which are dual to gauge theory instantons, but they may make some other interesting contributions vanish. We analyze how orientifold projections can remove these zero-modes and thus allow for new superpotential terms. These terms contribute to the dynamics of the effective gauge theory, for instance in the stabilization of runaway directions.

2009-11-13

0704.0265

Stefano Covino

A. Dolcini, F. Farfanelli, S. Ciprini, A. Treves, S. Covino, G. Tosti, E. Pian, B. Sbarufatti, E. Molinari, G. Chincarini, F.M. Zerbi, G. Malaspina, P. Conconi, L. Nicastro, E. Palazzi, V. Testa, F. Vitali, L.A. Antonelli, J. Danziger, G. Tagliaferri, E. Meurs, S. Vergani, A. Fernandez-Soto, E. Distefano, G. Cutispoto, F. D'Alessio

REM near-IR and optical multiband observations of PKS2155-304 in 2005

This paper is the corrected version of the paper published in A&A 469 503. It contains the material in the "Errata Corrrige", in press in A&A

Astron.Astrophys.469:503,2007

10.1051/0004-6361:20066477

astro-ph

Spectral variability is the main tool for constraining emission models of BL Lac objects. By means of systematic observations of the BL Lac prototype PKS 2155-304 in the infrared-optical band, we explore variability on the scales of months, days and hours. We made our observations with the robotic 60 cm telescope REM located at La Silla, Chile. VRIJHK filters were used. PKS 2155-304 was observed from May to December 2005. The wavelength interval explored, the total number of photometric points and the short integration time render our photometry substantially superior to previous ones for this source. On the basis of the intensity and colour we distinguish three different states of the source, each of duration of months, which include all those described in the literature. In particular, we report the highest state ever detected in the H band. The source varied by a factor of 4 in this band, much more than in the V band (a factor ~2). The source softened with increasing intensity, contrary to the general pattern observed in the UV-X-ray bands. On five nights of November we had nearly continuous monitoring for 2-3 hours. A variability episode with a time scale of ~24 h is well documented, a much more rapid flare with t=1-2 h, is also apparent, but is supported by relatively few points.

2009-11-16

0704.0266

Jennifer L. Hoffman

Jennifer L. Hoffman

Supernova Polarization and the Type IIn Classification

5 pages, 4 figures; to appear in "Supernova 1987A: 20 Years After: Supernovae and Gamma-Ray Bursters", AIP, New York, eds. S. Immler, K.W. Weiler, and R. McCray. v2: References added, typos corrected, and figures slightly modified for legibility when reduced in size

AIP Conf.Proc.937:365-369,2007

10.1063/1.2803592

astro-ph

While the members of the Type IIn category of supernovae are united by the presence of strong multicomponent Balmer emission lines in their spectra, they are quite heterogeneous with respect to other properties such as Balmer line profiles, light curves, strength of radio emission, and intrinsic brightness. We are now beginning to see variety among SNe IIn in their polarimetric characteristics as well, some but not all of which may be due to inclination angle effects. The increasing number of known "hybrid" SNe with IIn-like emission lines suggests that circumstellar material may be more common around all types of SNe than previously thought. Investigation of the correlations between spectropolarimetric signatures and other IIn attributes will help us address the question of classification of "interacting SNe" and the possibility of distinguishing different groups within the diverse IIn subclass.

2009-06-23

0704.0267

Cynthia S. Froning

C.S. Froning, E.L. Robinson, and M.A. Bitner

Near-Infrared Spectra of the Black Hole X-Ray Binary, A0620-00

Accepted for publication in the Astrophysical Journal

Astrophys.J.663:1215-1224,2007

10.1086/518820

astro-ph

We present broadband NIR spectra of A0620-00 obtained with SpeX on the IRTF. The spectrum is characterized by a blue continuum on which are superimposed broad emission lines of HI and HeII and a host of narrower absorption lines of neutral metals and molecules. Spectral type standard star spectra scaled to the dereddened spectrum of A0620-00 in K exceed the A0620-00 spectrum in J and H for all stars of spectral type K7V or earlier, demonstrating that the donor star, unless later than K7V, cannot be the sole NIR flux source in A0620-00. In addition, the atomic absorption lines in the K3V spectrum are too weak with respect to those of A0620-00 even at 100% donor star contribution, restricting the spectral type of the donor star in A0620-00 to later than K3V. Comparison of the A0620-00 spectrum to scaled K star spectra indicates that the CO absorption features are significantly weaker in A0620-00 than in field dwarf stars. Fits of scaled model spectra of a Roche lobe-filling donor star to the spectrum of A0620-00 show that the best match to the CO absorption lines is obtained when the C abundance is reduced to [C/H] = -1.5. The donor star contribution in the H waveband is determined to be 82+-2%. Combined with previous published results from Froning & Robinson (2001) and Marsh et al. (1994), this gives a precise mass for the black hole in A0620-00 of M_BH = 9.7+-0.6 M_solar.

2009-06-23

0704.0268

Mark Whitney

Mark Whitney, Nemanja Isailovic, Yatish Patel, John Kubiatowicz

Automated Generation of Layout and Control for Quantum Circuits

16 pages, 11 figures, To appear in ACM Computing Frontiers 2007, this version contains expanded related work

quant-ph

We present a computer-aided design flow for quantum circuits, complete with automatic layout and control logic extraction. To motivate automated layout for quantum circuits, we investigate grid-based layouts and show a performance variance of four times as we vary grid structure and initial qubit placement. We then propose two polynomial-time design heuristics: a greedy algorithm suitable for small, congestion-free quantum circuits and a dataflow-based analysis approach to placement and routing with implicit initial placement of qubits. Finally, we show that our dataflow-based heuristic generates better layouts than the state-of-the-art automated grid-based layout and scheduling mechanism in terms of latency and potential pipelinability, but at the cost of some area.

2009-09-29

0704.0269

Manasvita Joshi

M. Joshi and M. Boettcher

Modeling the Spectral Energy Distribution and Variability of 3C 66A during the WEBT campaign of 2003 -- 2004

23 pages, 9 figures, submitted to and accepted for publication in ApJ

Astrophys.J.662:884-891,2007

10.1086/518210

astro-ph

The BL Lac object 3C 66A was observed in an extensive multiwavelength monitoring campaign from July 2003 till April 2004. The spectral energy distribution (SED) was measured over the entire electromagnetic spectrum, with flux measurements from radio to X-ray frequencies and upper limits in the very high energy (VHE) gamma-ray regime. Here, we use a time-dependent leptonic jet model to reproduce the SED and optical spectral variability observed during our multiwavelength campaign. Our model simulations could successfully reproduce the observed SED and optical light curves and predict an intrinsic cutoff value for the VHE gamma-ray emission at ~ 4 GeV. The effect of the optical depth due to the intergalactic infrared background radiation (IIBR) on the peak of the high-energy component of 3C 66A was found to be negligible. Also, the presence of a broad line region (BLR) in the case of 3C 66A may play an important role in the emission of gamma-ray photons when the emission region is very close to the central engine, but further out, the production mechanism of hard X-ray and gamma-ray photons becomes rapidly dominated by synchrotron self-Compton emission. We further discuss the possibility of an observable X-ray spectral variability pattern. The simulated results do not predict observable hysteresis patterns in the optical or soft X-ray regimes for major flares on multi-day time scales.

2009-06-23

0704.0270

Xavier Bonfils

X. Bonfils, M. Mayor, X. Delfosse, T. Forveille, M. Gillon, C. Perrier, S. Udry, F. Bouchy, C. Lovis, F. Pepe, D. Queloz, N. C. Santos and J.-L. Bertaux

The HARPS search for southern extra-solar planets. X. A m sin i = 11 Mearth planet around the nearby spotted M dwarf GJ 674

submitted to A&A (January 09, 2007)

10.1051/0004-6361:20077068

astro-ph

Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms. Aims: This motivates planet searches around stars which are significantly more massive or less massive than the Sun, and in particular our radial velocity search for planets around very-low mass stars. Methods: As part of that program, we obtained measurements of GJ 674, an M2.5 dwarf at d=4.5 pc, which have a dispersion much in excess of their internal errors. An intensive observing campaign demonstrates that the excess dispersion is due to two superimposed coherent signals, with periods of 4.69 and 35 days. Results: These data are well described by a 2-planet Keplerian model where each planet has a ~11 Mearth minimum mass. A careful analysis of the (low level) magnetic activity of GJ 674 however demonstrates that the 35-day period coincides with the stellar rotation period. This signal therefore originates in a spot inhomogeneity modulated by stellar rotation. The 4.69-day signal on the other hand is caused by a bona-fide planet, GJ 674b. Conclusion: Its detection adds to the growing number of Neptune-mass planets around M-dwarfs, and reinforces the emerging conclusion that this mass domain is much more populated than the jovian mass range. We discuss the metallicity distributions of M dwarf with and without planets and find a low 11% probability that they are drawn from the same parent distribution. Moreover, we find tentative evidence that the host star metallicity correlates with the total mass of their planetary system.

2009-11-13

0704.0272

Monica Ivette Rodriguez

Monica Ivette Rodriguez, Tommy Wiklind, Ronald J. Allen, Vladimir Escalante, and Laurent Loinard

A Comparison between Anomalous 6-cm H$_2$CO Absorption and CO(1-0) Emission in the L1204/S140

9 pages 6 figures ApJ:accepted

Astrophys.J.663:824-833,2007

10.1086/518553

astro-ph

We report observations of the dust cloud L1204 with the Onsala 25-m telescope in the 6 cm (1$_{11}-1_{10}$) transition of \htco. The observed region includes the S140 H${\alpha}$ arc. This spectral line is seen here in absorption against the cosmic microwave background, indicating the presence of widespread warm molecular gas at intermediate densities. Overall, the distributions of H$_2$CO and CO (taken from the literature) are fairly similar, though significant differences exist at small scales. Most notably, while the CO peak is nearly coincident with the S140 H${\alpha}$ arc, the maximum H$_2$CO absorption is clearly separated from it by a full 10$'$ beam ($\sim$ 3 pc). We argue that these differences result from differing abundances and excitation requirements. The CO(1-0) line is more optically thick and more biased towards warm gas than the H$_2$CO 6 cm line. On the other hand, formaldehyde is more easily photodissociated and is, therefore, a poorer tracer of the molecular gas located immediately behind Photon Dominated Regions.

2009-06-23

0704.0276

Maik Wolleben

M. Wolleben

A New Model For The Loop-I (The North Polar Spur) Region

17 pages, 6 figures, to appear in ApJ

Astrophys.J.664:349-356,2007

10.1086/518711

astro-ph

The North Polar Spur (NPS) is the brightest filament of Loop I, a large circular feature in the radio continuum sky. In this paper, a model consisting of two synchrotron emitting shells is presented that reproduces large-scale structures revealed by recent polarization surveys. The polarized emission of the NPS is reproduced by one of these shells. The other shell, which passes close to the Sun, gives rise to polarized emission towards the Galactic poles. It is proposed that X-ray emission seen towards the NPS is produced by interaction of the two shells. Two OB-associations coincide with the centers of the shells. A formation scenario of the Loop I region is suggested.

2009-06-23

0704.0279

Andreea O. Petric

A. O. Petric and M. P. Rupen

HI velocity dispersion in NGC 1058

29 pages, 16 figures reduced to the lowest qual. to fit the astro-ph size requirements, accepted by AJ

Astron.J.134:1952-1962,2007

10.1086/518558

astro-ph

We present excellent resolution and high sensitivity Very Large Array (VLA) observations of the 21cm HI line emission from the face-on galaxy NGC 1058, providing the first reliable study of the HI profile shapes throughout the entire disk of an external galaxy. Our observations show an intriguing picture of the interstellar medium; throughout this galaxy velocity-- dispersions range between 4 to 15 km/sec but are not correlated with star formation, stars or the gaseous spiral arms. The velocity dispersions decrease with radius, but this global trend has a large scatter as there are several isolated, resolved regions of high dispersion. The decline of star light with radius is much steeper than that of the velocity dispersions or that of the energy in the gas motions.

2009-06-23

0704.0280

Ronald F. Webbink

Ronald F. Webbink (University of Illinois at Urbana-Champaign)

Common Envelope Evolution Redux

25 pages, 6 figures. To appear in "Short Period Binary Stars", ed. E.F. Milone, D.A. Leahy, & D.W. Hobill (Springer)

10.1007/978-1-4020-6544-6_13

astro-ph

Common envelopes form in dynamical time scale mass exchange, when the envelope of a donor star engulfs a much denser companion, and the core of the donor plus the dense companion star spiral inward through this dissipative envelope. As conceived by Paczynski and Ostriker, this process must be responsible for the creation of short-period binaries with degenerate components, and, indeed, it has proven capable of accounting for short-period binaries containing one white dwarf component. However, attempts to reconstruct the evolutionary histories of close double white dwarfs have proven more problematic, and point to the need for enhanced systemic mass loss, either during the close of the first, slow episode of mass transfer that produced the first white dwarf, or during the detached phase preceding the final, common envelope episode. The survival of long-period interacting binaries with massive white dwarfs, such as the recurrent novae T CrB and RS Oph, also presents interpretative difficulties for simple energetic treatments of common envelope evolution. Their existence implies that major terms are missing from usual formulations of the energy budget for common envelope evolution. The most plausible missing energy term is the energy released by recombination in the common envelope, and, indeed, a simple reformulation the energy budget explicitly including recombination resolves this issue.

2015-11-11

0704.0281

Denis Richard

Denis Richard

The Source of Turbulence in Astrophysical Disks: An Ill-posed Problem.

UCSC-NASA Ames Research Center Workshop on Stellar and Planets Formation March 29, 2007

astro-ph

An critical overview of the current state of research in turbulence in astrophysical disks.

2007-05-23

0704.0287

Pablo M. Saz Parkinson

Pablo M. Saz Parkinson (Milagro Collaboration)

Search for Very High Energy Emission from Gamma-Ray Bursts using Milagro

To appear in "Proceedings of the First International GLAST Symposium", Febuary 5-8, 2007, Stanford University, AIP, Eds. S. Ritz, P. F. Michelson, and C. Meegan

10.1063/1.2757406

astro-ph

Gamma-Ray Bursts (GRBs) have been detected at GeV energies by EGRET and models predict emission at > 100 GeV. Milagro is a wide field (2 sr) high duty cycle (> 90 %) ground based water Cherenkov detector that records extensive air showers in the energy range 100 GeV to 100 TeV. We have searched for very high energy emission from a sample of 106 gamma-ray bursts (GRB) detected since the beginning of 2000 by BATSE, BeppoSax, HETE-2, INTEGRAL, Swift or the IPN. No evidence for emission from any of the bursts has been found and we present upper limits from these bursts.

2009-11-13

0704.0290

Jarrod R. Hurley

Jarrod R. Hurley, Sverre J. Aarseth, Michael M. Shara

The core binary fractions of star clusters from realistic simulations

34 pages, 12 figures, accepted for publication in the Astrophysical Journal

Astrophys.J.665:707-718,2007

10.1086/517879

astro-ph

We investigate the evolution of binary fractions in star clusters using N-body models of up to 100000 stars. Primordial binary frequencies in these models range from 5% to 50%. Simulations are performed with the NBODY4 code and include a full mass spectrum of stars, stellar evolution, binary evolution and the tidal field of the Galaxy. We find that the overall binary fraction of a cluster almost always remains close to the primordial value, except at late times when a cluster is near dissolution. A critical exception occurs in the central regions where we observe a marked increase in binary fraction with time -- a simulation starting with 100000 stars and 5% binaries reached a core binary frequency as high as 40% at the end of the core-collapse phase (occurring at 16 Gyr with ~20000 stars remaining). Binaries are destroyed in the core by a variety of processes as a cluster evolves, but the combination of mass-segregation and creation of new binaries in exchange interactions produces the observed increase in relative number. We also find that binaries are cycled into and out of cluster cores in a manner that is analogous to convection in stars. For models of 100000 stars we show that the evolution of the core-radius up to the end of the initial phase of core-collapse is not affected by the exact value of the primordial binary frequency (for frequencies of 10% or less). We discuss the ramifications of our results for the likely primordial binary content of globular clusters.

2009-06-23

0704.0292

Gregory Soyez

Gavin P. Salam and Gregory Soyez

A practical Seedless Infrared-Safe Cone jet algorithm

42 pages, 11 figures. SISCone, the C++ implementation of the algorithm, is available at http://projects.hepforge.org/siscone/ (standalone), http://www.lpthe.jussieu.fr/~salam/fastjet/ (FastJet plugin). v2: FastJet URL corrected

JHEP 0705:086,2007

10.1088/1126-6708/2007/05/086

hep-ph

Current cone jet algorithms, widely used at hadron colliders, take event particles as seeds in an iterative search for stable cones. A longstanding infrared (IR) unsafety issue in such algorithms is often assumed to be solvable by adding extra `midpoint' seeds, but actually is just postponed to one order higher in the coupling. A proper solution is to switch to an exact seedless cone algorithm, one that provably identifies all stable cones. The only existing approach takes N 2^N time to find jets among N particles, making it unusable at hadron level. This can be reduced to N^2 ln(N) time, leading to code (SISCone) whose speed is similar to that of public midpoint implementations. Monte Carlo tests provide a strong cross-check of an analytical proof of the IR safety of the new algorithm, and the absence of any 'R_{sep}' issue implies a good practical correspondence between parton and hadron levels. Relative to a midpoint cone, the use of an IR safe seedless algorithm leads to modest changes for inclusive jet spectra, mostly through reduced sensitivity to the underlying event, and significant changes for some multi-jet observables.

2009-11-13

0704.0293

Mikhail Voloshin

S. Dubynskiy, A. Le Yaouanc, L. Oliver, J.-C. Raynal and M.B. Voloshin

Isospin breaking in the yield of heavy meson pairs in e+e- annihilation near threshold

16 pages, 2 figures

Phys.Rev.D75:113001,2007

10.1103/PhysRevD.75.113001

FTPI-MINN-07/08, UMN-TH-2541/07, LPT-Orsay/07-19

hep-ph

We revisit the problem of interplay between the strong and the Coulomb interaction in the charged-to-neutral yield ratio for $B {\bar B}$ and $D {\bar D}$ pairs near their respective thresholds in $e^+e^-$ annihilation. We consider here a realistic situation with a resonant interaction in the isospin I=0 channel and a nonresonant strong scattering amplitude in the I=1 state. We find that the yield ratio has a smooth behavior depending on the scattering phase in the I=1 channel. The same approach is also applicable to the $K {\bar K}$ production at the $\phi(1020)$ resonance, where the Coulomb effect in the charged-to-neutral yield ratio is generally sensitive to the scattering phases in both the isoscalar and the isovector channels. Furthermore, we apply the same approach to the treatment of the effect of the isotopic mass difference between the charged and neutral mesons and argue that the strong-scattering effects generally result in a modification to the pure kinematical effect of this mass difference.

2008-11-26

0704.0294

Scott A. Yost

B.F.L. Ward and S.A. Yost

QED x QCD Resummation and Shower/ME Matching for LHC Physics

12 pages, LaTex with packages amsmath, amssymb

ActaPhys.Polon.B38:2395-2403,2007

BU-HEPP-07/02

hep-ph

We present the theory of QED x QCD resummation and its interplay with shower/matrix element matching in precision LHC physics scenarios. We illustrate the theory using single heavy gauge boson production at hadron colliders.

2008-11-26

0704.0296

Itzhak Bars

Itzhak Bars and Bora Orcal

Generalized Twistor Transform And Dualities, With A New Description of Particles With Spin, Beyond Free and Massless

33 pages

Phys.Rev.D75:104015,2007

10.1103/PhysRevD.75.104015

USC-07/HEP-B3

hep-th

A generalized twistor transform for spinning particles in 3+1 dimensions is constructed that beautifully unifies many types of spinning systems by mapping them to the same twistor, thus predicting an infinite set of duality relations among spinning systems with different Hamiltonians. Usual 1T-physics is not equipped to explain the duality relationships and unification between these systems. We use 2T-physics in 4+2 dimensions to uncover new properties of twistors, and expect that our approach will prove to be useful for practical applications as well as for a deeper understanding of fundamental physics. Unexpected structures for a new description of spinning particles emerge. A unifying symmetry SU(2,3) that includes conformal symmetry SU(2,2)=SO(4,2) in the massless case, turns out to be a fundamental property underlying the dualities of a large set of spinning systems, including those that occur in high spin theories. This may lead to new forms of string theory backgrounds as well as to new methods for studying various corners of M theory. In this paper we present the main concepts, and in a companion paper we give other details.

2008-11-26

0704.0297

Sung-Chul Yoon

Sung-Chul Yoon, Philipp Podsiadlowski and Stephan Rosswog

Remnant evolution after a carbon-oxygen white dwarf merger

15 pages, 15 figures, 3 tables, submitted to MNRAS (Low resolution version; a high resolution version can be found at: http://www.astro.uva.nl/~scyoon/papers/wdmerger.pdf)

10.1111/j.1365-2966.2007.12161.x

astro-ph

We systematically explore the evolution of the merger of two carbon-oxygen (CO) white dwarfs. The dynamical evolution of a 0.9 Msun + 0.6 Msun CO white dwarf merger is followed by a three-dimensional SPH simulation. We use an elaborate prescription in which artificial viscosity is essentially absent, unless a shock is detected, and a much larger number of SPH particles than earlier calculations. Based on this simulation, we suggest that the central region of the merger remnant can, once it has reached quasi-static equilibrium, be approximated as a differentially rotating CO star, which consists of a slowly rotating cold core and a rapidly rotating hot envelope surrounded by a centrifugally supported disc. We construct a model of the CO remnant that mimics the results of the SPH simulation using a one-dimensional hydrodynamic stellar evolution code and then follow its secular evolution. The stellar evolution models indicate that the growth of the cold core is controlled by neutrino cooling at the interface between the core and the hot envelope, and that carbon ignition in the envelope can be avoided despite high effective accretion rates. This result suggests that the assumption of forced accretion of cold matter that was adopted in previous studies of the evolution of double CO white dwarf merger remnants may not be appropriate. Our results imply that at least some products of double CO white dwarfs merger may be considered good candidates for the progenitors of Type Ia supernovae. In this case, the characteristic time delay between the initial dynamical merger and the eventual explosion would be ~10^5 yr. (Abridged).

2019-08-19

0704.0307

Eric L. N. Jensen

Eric L. N. Jensen (1), Saurav Dhital (1,2), Keivan G. Stassun (2), Jenny Patience (3), William Herbst (4), Frederick M. Walter (5), Michal Simon (5), Gibor Basri (6); (1 - Swarthmore College; 2 - Vanderbilt; 3 - Caltech; 4 - Wesleyan University; 5 - SUNY Stony Brook; 6 - UC Berkeley)

Periodic accretion from a circumbinary disk in the young binary UZ Tau E

Accepted by the Astronomical Journal; to appear July 2007; Corrected minor typos

Astron.J.134:241-251,2007

10.1086/518408

astro-ph

Close pre-main-sequence binary stars are expected to clear central holes in their protoplanetary disks, but the extent to which material can flow from the circumbinary disk across the gap onto the individual circumstellar disks has been unclear. In binaries with eccentric orbits, periodic perturbation of the outer disk is predicted to induce mass flow across the gap, resulting in accretion that varies with the binary period. This accretion may manifest itself observationally as periodic changes in luminosity. Here we present a search for such periodic accretion in the pre-main-sequence spectroscopic binary UZ Tau E. We present BVRI photometry spanning three years; we find that the brightness of UZ Tau E is clearly periodic, with a best-fit period of 19.16 +/- 0.04 days. This is consistent with the spectroscopic binary period of 19.13 days, refined here from analysis of new and existing radial velocity data. The brightness of UZ Tau E shows significant random variability, but the overall periodic pattern is a broad peak in enhanced brightness, spanning more than half the binary orbital period. The variability of the H-alpha line is not as clearly periodic, but given the sparseness of the data, some periodic component is not ruled out. The photometric variations are in good agreement with predictions from simulations of binaries with orbital parameters similar to those of UZ Tau E, suggesting that periodic accretion does occur from circumbinary disks, replenishing the inner disks and possibly extending the timescale over which they might form planets.

2009-06-23

0704.0310

Xiang Liu

Xiang Liu, Lang Cui, Wen-Feng Luo, Wei-Zhao Shi, Hua-Gang Song (Urumqi Observatory, NAOC)

VLBI observations of nineteen GHz-Peaked-Spectrum radio sources at 1.6 GHz

11 pages, 12 figures, to appear in AA

A&A 470, 97-104 (2007)

10.1051/0004-6361:20077265

astro-ph

Aims and Methods: We present the results of VLBI observations of nineteen GHz-Peaked-Spectrum (GPS) radio sources at 1.6 GHz. Of them, 15 sources are selected from the Parkes Half Jansky (PHJ) sample (Snellen 2002), 4 others are from our previous observation list. We aimed at imaging the structure of GPS sources, searching for Compact Symmetric Objects (CSOs) and studying the absorption for the convex radio spectra of GPS sources. Results: We obtained total intensity 1.6 GHz VLBI images of 17 sources for the first time. Of them, 80% show mini-double-lobe radio structure, indicating that they are CSOs or candidates, and their host AGNs could be edge-on to us. This result suggests that there is a high incidence of mini double-lobe sources (or CSOs) in the PHJ sample. The sources J0323+0534, J1135-0021, J1352+0232, J2058+0540, J2123-0112 and J2325-0344 with measured redshift, showing double-lobe structure with sizes of <1 kpc, are classified as CSOs. Three sources J1057+0012, J1600-0037 and J1753+2750 are considered as core-jet sources according to their morphologies and flux variability.

2007-07-10

0704.0312

Geraint F. Lewis

Matthew J. Francis, Geraint F. Lewis, Eric V. Linder

Power Spectra to 1% Accuracy between Dynamical Dark Energy Cosmologies

9 pages, 14 figures, submitted to MNRAS

Mon.Not.Roy.Astron.Soc.380:1079,2007

10.1111/j.1365-2966.2007.12139.x

GFL-001

astro-ph

For dynamical dark energy cosmologies we carry out a series of N-body gravitational simulations, achieving percent level accuracy in the relative mass power spectra at any redshift. Such accuracy in the power spectrum is necessary for next generation cosmological mass probes. Our matching procedure reproduces the CMB distance to last scattering and delivers subpercent level power spectra at z=0 and z~3. We discuss the physical implications for probing dark energy with surveys of large scale structure.

2009-06-23

0704.0316

Alister W. Graham

Alister W. Graham, Simon P. Driver, Paul D. Allen, Jochen Liske

The Millennium Galaxy Catalogue: The local supermassive black hole mass function in early- and late-type galaxies

10 pages of text plus 5 of figs and refs. MNRAS, accepted.

Mon.Not.Roy.Astron.Soc.378:198-210,2007

10.1111/j.1365-2966.2007.11770.x

astro-ph

We provide a new estimate of the local supermassive black hole mass function using (i) the empirical relation between supermassive black hole mass and the Sersic index of the host spheroidal stellar system and (ii) the measured (spheroid) Sersic indices drawn from 10k galaxies in the Millennium Galaxy Catalogue. The observational simplicity of our approach, and the direct measurements of the black hole predictor quantity, i.e. the Sersic index, for both elliptical galaxies and the bulges of disc galaxies makes it straightforward to estimate accurate black hole masses in early- and late-type galaxies alike. We have parameterised the supermassive black hole mass function with a Schechter function and find, at the low-mass end, a logarithmic slope (1+alpha) of ~0.7 for the full galaxy sample and ~1.0 for the early-type galaxy sample. Considering spheroidal stellar systems brighter than M_B = -18 mag, and integrating down to black hole masses of 10^6 M_sun, we find that the local mass density of supermassive black holes in early-type galaxies rho_{bh, early-type} = (3.5+/-1.2) x 10^5 h^3_{70} M_sun Mpc^{-3}, and in late-type galaxies rho_{bh, late-type} = (1.0+/-0.5) x 10^5 h^3_{70} M_sun Mpc^{-3}. The uncertainties are derived from Monte Carlo simulations which include uncertainties in the M_bh-n relation, the catalogue of Sersic indices, the galaxy weights and Malmquist bias. The combined, cosmological, supermassive black hole mass density is thus Omega_{bh, total} = (3.2+/-1.2) x 10^{-6} h_70. That is, using a new and independent method, we conclude that (0.007+/-0.003) h^3_{70} per cent of the universe's baryons are presently locked up in supermassive black holes at the centres of galaxies.

2012-04-26

0704.0323

Heng Fan

Gui-Fang Dang, and Heng Fan

General sequential quantum cloning

4 pages

J.Phys.A 41, 155303 (2008)

10.1088/1751-8113/41/15/155303

quant-ph

Some multipartite quantum states can be generated in a sequential manner which may be implemented by various physical setups like microwave and optical cavity QED, trapped ions, and quantum dots etc. We analyze the general N to M qubits Universal Quantum Cloning Machine (UQCM) within a sequential generation scheme. We show that the N to M sequential UQCM is available. The case of d-level quantum states sequential cloning is also presented.

2012-05-23

0704.0328

Seung Woo Ham

S.W. Ham, E.J. Yoo, S.K. OH

Electroweak phase transitions in the MSSM with an extra $U(1)'$

17 pages, 2 tables, 3 figures

Phys.Rev.D76:075011,2007

10.1103/PhysRevD.76.075011

hep-ph

We investigate the possibility of electroweak phase transition in the minimal supersymmetric standard model (MSSM) with an extra $U(1)'$. This model has two Higgs doublets and a singlet, in addition to a singlet exotic quark superfield. We find that at the one-loop level this model may accommodate the electroweak phase transitions that are strongly first-order in a reasonably large region of the parameter space. In the parameter region where the phase transitions take place, we observe that the lightest scalar Higgs boson has a smaller mass when the strength of the phase transition becomes weaker. Also, the other three heavier neutral Higgs bosons get more large masses when the strength of the phase transition becomes weaker.

2008-11-26

0704.0330

Jacobus Verbaarschot

K. Splittorff and J.J.M. Verbaarschot

Random Matrix Theory at Nonzero $\mu$ and $T$

Invited talk at YKIS2006, YITP-Kyoto, 10 pages, 10 figures

Prog.Theor.Phys.Suppl.168:265-275,2007

10.1143/PTPS.168.265

hep-ph

We review applications of random matrix theory to QCD at nonzero temperature and chemical potential. The chiral phase transition of QCD and QCD-like theories is discussed in terms of eigenvalues of the Dirac operator. We show that for QCD at $\mu \ne 0$, which has a sign problem, the discontinuity in the chiral condensate is due to an alternative to the Banks-Casher relation. The severity of the sign problem is analyzed in the microscopic domain of QCD.

2008-11-26

0704.0340

Fam Le Kien

Fam Le Kien, S. Dutta Gupta, and K. Hakuta

Phonon-mediated decay of an atom in a surface-induced potential

14 pages, 15 figures

quant-ph

We study phonon-mediated transitions between translational levels of an atom in a surface-induced potential. We present a general master equation governing the dynamics of the translational states of the atom. In the framework of the Debye model, we derive compact expressions for the rates for both upward and downward transitions. Numerical calculations for the transition rates are performed for a deep silica-induced potential allowing for a large number of bound levels as well as free states of a cesium atom. The total absorption rate is shown to be determined mainly by the bound-to-bound transitions for deep bound levels and by bound-to-free transitions for shallow bound levels. Moreover, the phonon emission and absorption processes can be orders of magnitude larger for deep bound levels as compared to the shallow bound ones. We also study various types of transitions from free states. We show that, for thermal atomic cesium with temperature in the range from 100 $\mu$K to 400 $\mu$K in the vicinity of a silica surface with temperature of 300 K, the adsorption (free-to-bound decay) rate is about two times larger than the heating (free-to-free upward decay) rate, while the cooling (free-to-free downward decay) rate is negligible.

2007-05-23

0704.0341

Boris Ermolaev

B.I. Ermolaev, M. Greco, S.I. Troyan

Infrared Evolution Equations: Method and Applications

Talk given at Cracow Epiphany conference on precision physics and Monte Carlos for LHS. 4-6 January 2007, Cracow, Poland. 12 pp, 3 figures.

Acta Phys.Polon.B38:2243-2260,2007

hep-ph

It is a brief review on composing and solving Infrared Evolution Equations. They can be used in order to calculate amplitudes of high-energy reactions in different kinematic regions in the double-logarithmic approximation.

2011-04-11

0704.0344

Fabrizio Tavecchio

L. Maraschi, G. Ghisellini, F. Tavecchio

The Blazar Spectral Sequence and GLAST

3 pages, 4 figures. Proceedings of the First GLAST Symposium, to be published

AIP Conf.Proc.921:160-162,2007

10.1063/1.2757292

astro-ph

The present status and understanding of the "spectral sequence" of blazars is discussed in the perspective of the upcoming GLAST launch. The vast improvement in sensitivity will allow to i) determine more objectively the "average" gamma-ray properties of classes objects ii) probe more deeply the ratio between accretion power and jet power in different systems.

2009-06-23

0704.0346

Kenji Hamaguchi

Kenji Hamaguchi, the Suzaku Eta Carinae team and the Carinae D-1 team

Diffuse X-ray Emission from the Carina Nebula Observed with Suzaku

4 pages, 2 figures, proceeding of the extreme universe in the Suzaku era, held in Kyoto, Japan on Dec. 4-8, 2006

10.1143/PTPS.169.174

astro-ph

A number of giant HII regions are associated with soft diffuse X-ray emission. Among these, the Carina nebula possesses the brightest soft diffuse emission. The required plasma temperature and thermal energy can be produced by collisions or termination of fast winds from main-sequence or embedded young O stars, but the extended emission is often observed from regions apart from massive stellar clusters. The origin of the X-ray emission is unknown. The XIS CCD camera onboard Suzaku has the best spectral resolution for extended soft sources so far, and is therefore capable of measuring key emission lines in the soft band. Suzaku observed the core and the eastern side of the Carina nebula (Car-D1) in 2005 Aug and 2006 June, respectively. Spectra of the south part of the core and Car-D1 similarly showed strong L-shell lines of iron ions and K-shell lines of silicon ions, while in the north of the core these lines were much weaker. Fitting the spectra with an absorbed thin-thermal plasma model showed kT~0.2, 0.6 keV and NH~1-2e21 cm-2 with a factor of 2-3 abundance variation in oxygen, magnesium, silicon and iron. The plasma might originate from an old supernova, or a super shell of multiple supernovae.

2009-11-13

0704.0348

Grazyna Stasinska

G. Stasinska

What can emission lines tell us?

55 pages, Lectures given at the XVIII Canary Island Winterschool "The emission line Universe", to be published by Cambridge University Press

10.1017/CBO9780511552038.003

astro-ph

1 Generalities 2 Empirical diagnostics based on emission lines 3 Photoionization modelling 4 Pending questions 5 Appendix: Lists of useful lines and how to deal with them

2023-06-07

0704.0350

Sonia Fornasier

S. Fornasier, E. Dotto, O. Hainaut, F. Marzari, H. Boehnhardt, F. De Luise, M. A. Barucci

Visible spectroscopic and photometric survey of Jupiter Trojans: final results on dynamical families

52 pages, 14 figure, paper accepted for publication in Icarus

10.1016/j.icarus.2007.03.033

astro-ph

We present the results of a visible spectroscopic and photometric survey of Jupiter Trojans belonging to different dynamical families carried out at the ESO-NTT telescope. We obtained data on 47 objects, 23 belonging to the L5 swarm and 24 to the L4 one. These data together with those already published by Fornasier et al. (2004a) and Dotto et al. (2006), constitute a total sample of visible spectra for 80 objects. The survey allows us to investigate six families (Aneas, Anchises, Misenus, Phereclos, Sarpedon, Panthoos) in the L5 cloud and four L4 families (Eurybates, Menelaus, 1986 WD and 1986 TS6). The sample that we measured is dominated by D--type asteroids, with the exception of the Eurybates family in the L4 swarm, where there is a dominance of C- and P-type asteroids. All the spectra that we obtained are featureless with the exception of some Eurybates members, where a drop--off of the reflectance is detected shortward of 5200 A. Similar features are seen in main belt C-type asteroids and commonly attributed to the intervalence charge transfer transition in oxidized iron. Our sample comprises fainter and smaller Trojans as compared to the literature's data and allows us to investigate the properties of objects with estimated diameter smaller than 40--50 km. The analysis of the spectral slopes and colors versus the estimated diameters shows that the blue and red objects have indistinguishable size distribution. We perform a statistical investigation of the Trojans's spectra property distributions as a function of their orbital and physical parameters, and in comparison with other classes of minor bodies in the outer Solar System. Trojans at lower inclination appear significantly bluer than those at higher inclination, but this effect is strongly driven by the Eurybates family.

2009-11-13