86 research outputs found
Peculiarities in the orbital and precessional variability of SS433 from INTEGRAL observations
Based on multiyear INTEGRAL observations of SS433, a composite IBIS/ISGRI
18-60 keV orbital light curve is constructed around zero precessional phase
. It shows a peculiar shape characterized by a significant excess
near the orbital phase , which is not seen in the softer 2-10
keV energy band. Such a shape is likely to be due to a complex asymmetric
structure of the funnel in a supercritical accretion disk in SS433. The orbital
light curve at 40-60 keV demonstrates two almost equal bumps at phases and , most likely due to nutation effects of the accretion
disk. The change of the off-eclipse 18-60 keV X-ray flux with the precessional
phase shows a double-wave form with strong primary maximum at
and weak but significant secondary maximum at . A weak
variability of the 18-60 keV flux in the middle of the orbital eclipse
correlated with the disk precessional phase is also observed. The joint
analysis of the broadband (18-60 keV) orbital and precessional light curves
obtained by INTEGRAL confirms the presence of a hot extended corona in the
central parts of the supercritical accretion disk and constrain the binary mass
ratio in SS433 in the range , confirming the black
hole nature of the compact object. Orbital and precessional light curves in the
hardest X-ray band 40-60 keV, which is free from emission from thermal X-ray
jets, are also best fitted by the same geometrical model with hot extended
corona at , stressing the conclusions of the modeling of the
broad-band X-ray orbital and precessional light curves.Comment: 6 pages. 12 figures, LATeX, submitted to Proc. 9th INTEGRAL Workshop
(Paris, 15-19 October 2012). To be published in Proc. of Scienc
Peculiar nature of hard X-ray eclipse in SS433 from INTEGRAL observations
The analysis of INTEGRAL observations (2003-2008) of superaccreting galactic
microquasar SS433 at precessional phases with the maximum disk opening angle is
carried out. The shape and width of the primary X-ray eclipse is found to be
strongly variable suggesting additional absorption in dense stellar wind and
gas outflows from the optical A7I-component. The joint modeling of X-ray
eclipse and precessional X-ray variability by a geometrical model suggests the
binary mass ratio q=m_x/m_v=0.3, allowing an explnation of peculiarities of the
optical variability of SS433, in particular, the substantial precessional
variability at the primary optical eclipse minimum. For the mass function of
the optical star f_v=0.268 M_\odot as derived from Hillwig and Gies (2008)
data, the obtained q yields the masses of the components m_x=5 M_\odot, m_v=15
M_\odot, confirming the black hole nature of the relativistic object in SS433.
The independence of the observed hard X-ray spectrum on the precession phase
suggests that hard X-ray emission is formed in an extended hot corona. The
Monte-Carlo simulations of the broadband X-ray spectrum of SS433 at the maximum
disk opening precessional phases allowed us to determine physical parameters of
the corona (temperature T_{cor}=20 keV, Thomson optical depth \tau=0.2), and to
estimate the jet mass outflow rate \dot M_j=3\times 10^{19} g/s yielding the
kinetic power of the jets \sim 10^{39} erg/s.Comment: 12 pages, 10 figures, Proc. 7th INTEGRAL Workshop, Copenhagen, 8-11
September 200
The Mass of the Compact Object in the X-Ray Binary Her X-1/HZ Her
We have obtained the first estimates of the masses of the components of the
Her X-1/HZ Her X-ray binary system taking into account non-LTE effects in the
formation of the H_gamma absorption line: mx=1.8Msun and mv=2.5Msun. These mass
estimates were made in a Roche model based on the observed radial-velocity
curve of the optical star, HZ Her. The masses for the X-ray pulsar and optical
star obtained for an LTE model lie are mx=0.85\pm0.15Msun and
mv=1.87\pm0.13Msun. These mass estimates for the components of Her X-1/HZ Her
derived from the radial-velocity curve should be considered tentative. Further
mass estimates from high-precision observations of the orbital variability of
the absorption profiles in a non-LTE model for the atmosphere of the optical
component should be made.Comment: 20 pages, 4 tables, 8 figure
Radial-velocity curves and theoretical spectral-line profiles of the components of low-mass close X-ray binary systems
We present the results of calculations of theoretical absorption-line profiles and radial-velocity curves for optical components in X-ray binary systems. Tidal distortion of the optical star and X-ray heating by incident radiation from the relativistic object are taken into account. An emission component forms whose intensity varies with orbital phase in the absorption-line profile in the presence of significant X-ray heating. As a result, the width of the line decreases rather than increases at quadrature. The line profiles and equivalent widths and the radial-velocity curves depend substantially on the parameters of the binary systems. This provides the possibility of directly determining component masses and orbital inclinations from high-resolution spectroscopic observations of X-ray binary systems. © 2005 Pleiades Publishing, Inc
Identification of the Mass Donor Star's Spectrum in SS 433
We present spectroscopy of the microquasar SS 433 obtained near primary
eclipse and disk precessional phase Psi = 0.0, when the accretion disk is
expected to be most ``face-on''. The likelihood of observing the spectrum of
the mass donor is maximized at this combination of orbital and precessional
phases since the donor is in the foreground and above the extended disk
believed to be present in the system. The spectra were obtained over four
different runs centered on these special phases. The blue spectra show clear
evidence of absorption features consistent with a classification of A3-7 I. The
behavior of the observed lines indicates an origin in the mass donor. The
observed radial velocity variations are in anti-phase to the disk, the
absorption lines strengthen at mid-eclipse when the donor star is expected to
contribute its maximum percentage of the total flux, and the line widths are
consistent with lines created in an A supergiant photosphere. We discuss and
cast doubt on the possibility that these lines represent a shell spectrum
rather than the mass donor itself. We re-evaluate the mass ratio of the system
and derive masses of 10.9 +/- 3.1 Msun and 2.9 +/- 0.7 Msun for the mass donor
and compact object plus disk, respectively. We suggest that the compact object
is a low mass black hole.
In addition, we review the behavior of the observed emission lines from both
the disk/wind and high velocity jets.Comment: submitted to ApJ, 24 pages, 7 figure
A Spectroscopic Study of Mass Outflows in the Interacting Binary RY Scuti
The massive interacting binary RY Scuti is an important representative of an
active mass-transferring system that is changing before our eyes and which may
be an example of the formation of a Wolf-Rayet star through tidal stripping.
Utilizing new and previously published spectra, we present examples of how a
number of illustrative absorption and emission features vary during the binary
orbit. We identify spectral features associated with each component, calculate
a new, double-lined spectroscopic binary orbit, and find masses of 7.1 +/- 1.2
M_sun for the bright supergiant and 30.0 +/- 2.1 M_sun for the hidden massive
companion. Through tomographic reconstruction of the component spectra from the
composite spectra, we confirm the O9.7 Ibpe spectral class of the bright
supergiant and discover a B0.5 I spectrum associated with the hidden massive
companion; however, we suggest that the latter is actually the spectrum of the
photosphere of the accretion torus immediately surrounding the massive
companion. We describe the complex nature of the mass loss flows from the
system in the context of recent hydrodynamical models for beta Lyr, leading us
to conclude RY Scuti has matter leaving the system in two ways: 1) a bipolar
outflow from winds generated by the hidden massive companion, and 2) mass from
the bright O9.7 Ibpe supergiant flowing from the region near the L2 point to
fill out a large, dense circumbinary disk. This circumbinary disk (radius ~ 1
AU) may feed the surrounding double-toroidal nebula (radius ~ 2000 AU).Comment: 41 pages with 7 tables and 11 figures, accepted to Ap
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