785 research outputs found
Orbital parameters of V 0332+53 from 2015 giant outburst data
We present the updated orbital solution for the transient Be X-ray binary V
0332+53 comple- menting historical measurements with the data from the
gamma-ray burst monitor onboard Fermi obtained during the outburst in
June-October 2015. We model the observed changes in the spin- frequency of the
pulsar and deduce the orbital parameters of the system. We significantly
improve existing constrains and show that contrary to the previous findings no
change in orbital parameters is required to explain the spin evolution of the
source during the outbursts in 1983, 2005 and 2015. The reconstructed intrinsic
spin-up of the neutron star during the latest outburst is found to be
comparable with previosly observed values and predictions of the accretion
torque theory.Comment: 3 pages, 2 figures, submitted to A&
An upper limit on nickel overabundance in the supercritical accretion disk wind of SS 433 from X-ray spectroscopy
We take advantage of a long (with a total exposure time of 120 ks) X-ray
observation of the unique Galactic microquasar SS 433, carried out with the
XMM-Newton space observatory, to search for a fluorescent line of neutral (or
weakly ionized) nickel at the energy 7.5 keV. We consider two models of the
formation of fluorescent lines in the spectrum of SS 433: 1) due to reflection
of hard X-ray radiation from a putative central source on the optically thick
walls of the accretion disk "funnel"; and 2) due to scattering of the radiation
coming from the hottest parts of the jets in the optically thin wind of the
system. It is shown, that for these cases, the photon flux of Ni I K
fluorescent line is expected to be 0.45 of the flux of Fe I K
fluorescent line at 6.4 keV, for the relative nickel overabundance , as observed in the jets of SS 433. For the continuum model without the
absorption edge of neutral iron, we set a 90 per cent upper limit on the flux
of the narrow Ni I K line at the level of ph
s cm. For the continuum model with the absorption edge, the
corresponding upper limit is ph s cm. At the
same time, for the Fe I K line, we measure the flux of
ph s cm. Taken at the face
value, the results imply that the relative overabundance of nickel in the wind
of the accretion disc should be at least 1.5 times less than the corresponding
excess of nickel observed in the jets of SS 433.Comment: 17 pages, 12 figures, 4 tables, Astronomy Letters, in press, 2018,
Volume 44, Issue
Population of persistent high mass X-ray binaries in the Milky Way
We present results of the study of persistent high mass X-ray binaries
(HMXBs) in the Milky Way, obtained from the deep INTEGRAL Galactic plane
survey. This survey provides us a new insight into the population of high mass
X-ray binaries because almost half of the whole sample consists of sources
discovered with INTEGRAL. It is demonstrated for the first time that the
majority of persistent HMXBs have supergiant companions and their luminosity
function steepens somewhere around ~2x10^{36} erg/s. We show that the spatial
density distribution of HMXBs correlates well with the star formation rate
distribution in the Galaxy. The vertical distribution of HMXBs has a
scale-height h~85 pc, that is somewhat larger than the distribution of young
stars in the Galaxy. We propose a simple toy model, which adequately describes
general properties of HMXBs in which neutron stars accrete a matter from the
wind of the its companion (wind-fed NS-HMXBs population). Using the elaborated
model we argue that a flaring activity of so-called supergiant fast X-ray
transients, the recently recognized sub-sample of HMXBs, is likely related with
the magnetic arrest of their accretion.Comment: 17 pages, 12 figures, accepted for publicatiopn in MNRA
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