12,325 research outputs found
On the outburst evolution of H1743-322: a 2008/2009 comparison
We present two observational campaigns performed with the RXTE satellite on
the black hole transient H 1743-322. The source was observed in outburst on two
separate occasions between October-November 2008 and May-July 2009. We have
carried out timing and spectral analysis of the data set, obtaining a complete
state classification of all the observations. We find that all the observations
are well described by using a spectral model consisting of a disk-blackbody, a
powerlaw + reflection + absorption and a gaussian emission component. During
the 2009 outburst the system followed the canonical evolution through all the
states seen in black hole transients. In the 2008 outburst only the hard states
were reached. The early evolution of the spectral parameters is consistent
between the two epochs, and it does not provide clues about the subsequent
behavior of the source. The variation of the flux associated to the two main
spectral components (i.e. disk and powerlaw) allows us to set a lower limit to
the orbital inclination of the system of >= 43{\deg}.Comment: 13 pages, 5 figures. Accepted for publication in MNRA
Fast variability as a tracer of accretion regimes in black hole transients
We present the rms-intensity diagram for black hole transients. Using
observations taken with the Rossi X-ray timing explorer we study the relation
between the root mean square (rms) amplitude of the variability and the net
count-rate during the 2002, 2004 and 2007 outbursts of the black hole X-ray
binary GX 339-4. We find that the rms-flux relation previously observed during
the hard state in X-ray binaries does not hold for the other states, when
different relations apply. These relations can be used as a good tracer of the
different accretion regimes. We identify the hard, soft and intermediate states
in the rms-intensity diagram. Transitions between the different states are seen
to produce marked changes in the rms-flux relation. We find that one single
component is required to explain the ~ 40 per cent variability observed at low
count rates, whereas no or very low variability is associated to the
accretion-disc thermal component.Comment: Accepted for publication in MNRAS. 6 pages, 4 figure
Rationality and Brauer group of a moduli space of framed bundles
We prove that the moduli spaces of framed bundles over a smooth projective
curve are rational. We compute the Brauer group of these moduli spaces to be
zero under some assumption on the stability parameter.Comment: 7 pages, to appear in Tbilisi Math. J; v2. reference adde
Precise prediction for the Higgs-Boson Masses in the SSM
The SSM is a simple supersymmetric extension of the Standard Model
(SM) capable of predicting neutrino physics in agreement with experiment. In
this paper we perform the complete one-loop renormalization of the neutral
scalar sector of the SSM with one generation of right-handed neutrinos
in a mixed on-shell/ scheme. The renormalization
procedure is discussed in detail, emphasizing conceptual differences to the
minimal (MSSM) and next-to-minimal (NMSSM) supersymmetric standard model
regarding the field renormalization and the treatment of non-flavor-diagonal
soft mass parameters, which have their origin in the breaking of -parity in
the SSM. We calculate the full one-loop corrections to the neutral
scalar masses of the SSM. The one-loop contributions are supplemented
by available MSSM higher-order corrections. We obtain numerical results for a
SM-like Higgs boson mass consistent with experimental bounds. We compare our
results to predictions in the NMSSM to obtain a measure for the significance of
genuine SSM-like contributions. We only find minor corrections due to
the smallness of the neutrino Yukawa couplings, indicating that the Higgs boson
mass calculations in the SSM are at the same level of accuracy as in
the NMSSM. Finally we show that the SSM can accomodate a Higgs boson
that could explain an excess of events at as reported by CMS, as well as the excess of events observed at LEP at a similar mass scale.Comment: Version published in EPJC. Numerical analysis improved, numerical
results for NMSSM comparison changed accordingly, overall conclusions
unchanged. 56 pages, 12 figure
A connection between accretion state and in an accreting neutron star: black hole-like soft state winds?
High resolution X-ray spectra of accreting stellar mass Black Holes reveal
the presence of accretion disc winds, traced by high ionisation Fe K lines.
These winds appear to have an equatorial geometry and to be observed only
during disc dominated states in which the radio jet is absent. Accreting
neutron star systems also show equatorial high ionisation absorbers. However,
the presence of any correlation with the accretion state has not been
previously tested. We have studied EXO 0748-676, a transient neutron star
system, for which we can reliably determine the accretion state, in order to
investigate the Fe K absorption/accretion state/jet connection. Not one of
twenty X-ray spectra obtained in the hard state revealed any significant Fe K
absorption line. However, intense Fe and Fe
(as well as a rarely observed Fe line plus S ; a blend of S and Ar ; Ca and Ca
, possibly produced by the same high ionisation
material) absorption lines ( eV, eV) are clearly detected during the only soft state
observation. This suggests that the connection between Fe K absorption and
states (and anticorrelation between the presence of Fe K absorption and jets)
is also valid for EXO 0748-676 and therefore it is not a unique property of
black hole systems but a more general characteristic of accreting sources.Comment: Accepted for publication in MNRAS Letter
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
Influence of diffusion on models for non-equilibrium wetting
It is shown that the critical properties of a recently studied model for
non-equilibrium wetting are robust if one extends the dynamic rules by
single-particle diffusion on terraces of the wetting layer. Examining the
behavior at the critical point and along the phase transition line, we identify
a special point in the phase diagram where detailed balance of the dynamical
processes is partially broken.Comment: 6 pages, 9 figure
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