Time-Delayed transfer functions simulations for LMXBs

Recent works (Steeghs & Casares 2002, Casares et al. 2003, Hynes et al. 2003) have demonstrated that Bowen flourescence is a very efficient tracer of the companion star in LMXBs. We present a numerical code to simulate time-delayed transfer functions in LMXBs, specific to the case of reprocessing in emission lines. The code is also able to obtain geometrical and binary parameters by fitting observed (X-ray + optical) light curves using simulated annealing methods. In this work we present the geometrical model for the companion star and the analytical model for the disc and show synthetic time-delay transfer functions for different orbital phases and system parameters.Comment: Contribution presented at the conference "Interacting Binaries: Accretion, Evolution and Outcomes", held in Cefalu, Sicily (Italy) in July 2004. To be published by AIP (American Institute of Physics), eds. L. A. Antonelli, L. Burderi, F. D'Antona, T. Di Salvo, G.L. Israel, L. Piersanti, O. Straniero, A. Tornambe. 4 pages, 4 figure

The 1953 Cosmic Ray Conference at Bagneres de Bigorre

The cosmic ray conference at Bagn`eres de Bigorre in July, 1953 organized by Patrick Blackett and Louis Leprince-Ringuet was a seminal one. It marked the beginning of sub atomic physics and its shift from cosmic ray research to research at the new high energy accelerators. The knowledge of the heavy unstable particles found in the cosmic rays was essentially correct in fact and interpretation and defined the experiments that needed to be carried out with the new accelerators. A large fraction of the physicists who had been using cosmic rays for their research moved to the accelerators. This conference can be placed in importance in the same category as two other famous conferences, the Solvay congress of 1927 and the Shelter Island Conference of 1948

The consequences of key audit matters on users: The case of Spain

The audit report has changed by adding a section to disclosure the key audit matters (KAM), among other changes. The KAM disclosure may have incremental investor’s usefulness. Thus, we study the influence of the KAM disclosure on investor usefulness using a short window and a year window market reaction, this is, a return and cumulative abnormal return model (CAR). Since most of the disclosure KAM studies are in a strong investor protection and common law system countries, we study the influence of the KAM disclosure in Spain. In Spain the audit report changes is mandatory for periods beginning on or after 17 June 2016. We find a one year market reaction and that the KAM disclosure is value relevant for investors, but not in a short market reaction to KAM disclosure. Albeit, finding a one year reaction, our findings are similar to the archival studies, which have found no market reaction to KAM disclosure. This may be due to the fact the information disclosure by KAM is already known by investors.info:eu-repo/semantics/acceptedVersio

Synthetic NLTE accretion disc spectra for the dwarf nova SS Cyg during an outburst cycle

Dwarf nova outbursts result from enhanced mass transport through the accretion disc of a cataclysmic variable system. We assess the question of whether these outbursts are caused by an enhanced mass transfer from the late-type main sequence star onto the white dwarf (so-called mass transfer instability model, MTI) or by a thermal instability in the accretion disc (disc instability model, DIM). We compute non-LTE models and spectra of accretion discs in quiescence and outburst and construct spectral time sequences for discs over a complete outburst cycle. We then compare our spectra to published optical spectroscopy of the dwarf nova SS Cygni. In particular, we investigate the hydrogen and helium line profiles that are turning from emission into absorption during the rise to outburst. The evolution of the hydrogen and helium line profiles during the rise to outburst and decline clearly favour the disc-instability model. Our spectral model sequences allow us to distinguish inside-out and outside-in moving heating waves in the disc of SS Cygni, which can be related to symmetric and asymmetric outburst light curves, respectively.Comment: 8 pages, 8 figures; accepted to A&

The Nature of the Secondary Star in the Black Hole X-Ray Transient V616 Mon (=A0620-00)

We have used NIRSPEC on Keck II to obtain $K$-band spectroscopy of the low mass X-ray binary V616 Mon (= A0620$-$00). V616 Mon is the proto-typical soft x-ray transient containing a black hole primary. As such it is important to constrain the masses of the binary components. The modeling of the infrared observations of ellipsoidal variations in this system lead to a derived mass of 11.0 M_{\sun} for the black hole. The validity of this derivation has been called into question due to the possiblity that the secondary star's spectral energy distribution is contaminated by accretion disk emission (acting to dilute the variations). Our new $K$-band spectrum of V616 Mon reveals a late-type K dwarf secondary star, but one that has very weak $^{\rm 12}$CO absorption features. Comparison of V616 Mon with SS Cyg leads us to estimate that the accretion disk supplies only a small amount of $K$-band flux, and the ellipsoidal variations are not seriously contaminated. If true, the derived orbital inclination of V616 Mon is not greatly altered, and the mass of the black hole remains large. A preliminary stellar atmosphere model for the $K$-band spectrum of V616 Mon reveals that the carbon abundance is approximately 50% of the solar value. We conclude that the secondary star in V616 Mon has either suffered serious contamination from the accretion of supernova ejecta that created the black hole primary, or it is the stripped remains of a formerly more massive secondary star, one in which the CNO cycle had been active.Comment: 20 pages, 5 figure

Quark Propagator and Chiral Symmetry with String Tension

General properties of the light and heavy quark propagators have been investigated in the context of string tension interaction. Confinement, chiral symmetry breaking, spectral properties of the propagator are analytically studied and numerically validated. We show that the propagator is analytic in the infrared region even for massless quarks with a non zero radius of convergence. Emergence of more than one mass scale is exemplified. Massless limit of the quark propagator does exhibit critical behaviour.Comment: 15 pages, 6 eps figures, LaTe

Pseudoscalar-Meson Octet-Baryon Coupling Constants from two-flavor Lattice QCD

We evaluate the pseudoscalar-meson octet-baryon coupling constants and the corresponding axial charges in eight channels ($\pi N\N$, $\pi\Sigma\Sigma$, $\pi\Lambda\Sigma$, $K\Lambda N$, $K \Sigma N$, $\pi\Xi\Xi$, $K\Lambda\Xi$ and $K\Sigma\Xi$) in lattice QCD with two flavors of dynamical quarks. The parameter $\alpha\equiv F/(F+D)$ representing the SU(3)-flavor symmetry is computed at each u,d-quark hopping parameter and at the flavor-SU(3) symmetric point where the three quark flavors are degenerate at the physical $s$-quark mass. In particular, we obtain $\alpha=0.395(6)$ at the SU(3) symmetric limit. The quark-mass dependences of the coupling constants are obtained by changing the $u$- and the $d$-quark masses and we find that the SU(3)-flavor symmetry is broken by only a few percent at each quark-mass we employ.Comment: 4 pages, Talk given at HYP-X, September 14-18, 2009, Tokai, Japa

Inducing charges and currents from extra dimensions

In a particular variant of Kaluza-Klein theory, the so-called induced-matter theory (IMT), it is shown that any configuration of matter may be geometrically induced from a five-dimensional vacuum space. By using a similar approach we show that any distribution of charges and currents may also be induced from a five-dimensional vacuum space. Whereas in the case of IMT the geometry is Riemannian and the fundamental equations are the five-dimensional Einstein equations in vacuum, here we consider a Minkowskian geometry and the five-dimensional Maxwell equations in vacuum.Comment: 8 pages. Accepted for publication in Modern Physics Letters