Downscattering due to Wind Outflows in Compact X-ray Sources: Theory and Interpretation

Abstract

A number of recent lines of evidence point towards the presence of hot, out-flowing plasma from the central regions of compact Galactic and extragalactic X-ray sources. Additionally, it has long been noted that many of these sources exhibit an ``excess'' continuum component, above 10 keV, usually attributed to Compton Reflection from a static medium. Motivated by these facts, as well as by recent observational constraints on the Compton reflection models - specifically apparently discrepant variability timescales for line and continuum components in some cases -- we consider possible effects of out-flowing plasma on the high-energy continuum spectra of accretion powered compact objects. We present a general formulation for photon downscattering diffusion which includes recoil and Comptonization effects due to divergence of the flow. We then develop an analytical theory for the spectral formation in such systems that allows us to derive formulae for the emergent spectrum. Finally we perform the analytical model fitting on several Galactic X-ray binaries. Objects which have been modeled with high-covering-fraction Compton reflectors, such as GS1353-64 are included in our analysis. In addition, Cyg X-3, is which is widely believed to be characterized by dense circumstellar winds with temperature of order 10^6 K, provides an interesting test case. Data from INTEGRAL and RXTE covering the 3-300 keV range are used in our analysis. We further consider the possibility that the widely noted distortion of the power-law continuum above 10 keV may in some cases be explained by these spectral softening effects.

16 pages, 5 figures, accepted for publication in the Astrophysical Journal and scheduled for 1 December 2004, vol 616 issue

References in corpus (10)

• Chandra/HETGS Spectroscopy of the Galactic Black Hole GX 339-4: A Relativistic Iron Line and Evidence for a Seyfert-like Warm Absorber
• Long-Term X-ray Spectral Variability in Seyfert 1 Galaxies
• INTEGRAL/SPI ground calibration
• Why is it Difficult to Detect a Millisecond Pulsar in Neutron Star X-ray Binaries?
• Outflows Near An Accreting Black Hole: Ionization and Temperature Structure
• First INTEGRAL observations of Cygnus X-3
• Broad redshifted line as a signature of outflow
• RXTE and BeppoSAX Observations of MCG -5-23-16: Reflection From Distant Cold Material
• Extended Emission from Cygnus X-3 Detected with Chandra
• First INTEGRAL Observations of Eight Persistent Neutron Star Low Mass X-ray Binaries

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• XTE J1550-564: INTEGRAL Observations of a Failed Outburst
• X-Ray Observations of V4641 SGR (= SAX J1819.3-2525) During the Brief and Violent Outburst of 2003
• Analysis of X-ray spectral variability and black hole mass determination of the NLS1 galaxy Mrk 766
• Variable mass accretion and failed wind explain changing look phenomena in NGC 1365