Mark Reynolds, Jon Miller
We present a systemic analysis of all of the stellar mass black hole binaries
(confirmed & candidate) observed by the Swift observatory up to June 2010. The
broad Swift bandpass enables a trace of disk evolution over an unprecedented
range in flux and temperature. The final data sample consists of 476 X-ray
spectra containing greater than 100 counts, in the 0.6 -- 10 keV band. This is
the largest sample of high quality CCD spectra of accreting black holes
published to date. In addition, strictly simultaneous data at optical/UV
wavelengths are available for 255 (54%) of these observations.
The data are modelled with a combination of an accretion disk and a hard
spectral component. For the hard component we consider both a simple power-law
and a thermal Comptonization model. An accretion disk is detected at greater
than the 5sigma confidence level in 61% of the observations. Lightcurves and
color-color diagrams are constructed for each system. Hardness luminosity and
disk fraction luminosity diagrams are constructed and are observed to be
consistent with those typically observed by RXTE, noting the sensitivity below
2 keV provided by Swift. The observed spectra have an average luminosity of ~
1% Eddington, though we are sensitive to accretion disks down to a luminosity
of 10^{-3} L_Edd. Thus this is also the largest sample of such cool accretion
disks studied to date. (abridged)
View original:
http://arxiv.org/abs/1112.2249
No comments:
Post a Comment