CORONA, JET, AND RELATIVISTIC LINE MODELS FORSUZAKU/RXTE/CHANDRA-HETG OBSERVATIONS OF THE CYGNUS X-1 HARD STATE

Abstract

Using Suzaku and the Rossi X-ray Timing Explorer (RXTE ), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states". Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary's focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c 2 . All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is > 40 GM/c 2 .

The photon-index–time-lag correlation in black hole X-ray binaries

“…For the formation and destruction of jets in black-hole and neutron-star binaries, the reader is referred to Kylafis et al (2012). Spectral information alone cannot reveal the accretion geometry: different models can result in very similar energy spectra (Nowak et al 2011). Significant advances in our understanding of how the X-ray mechanism in BHBs works can be achieved when we combine variability and spectral information.…”

Long term variability of Cygnus X-1

“…As shown, e.g., by Nowak et al (2011), the combination of the best resolution and the most broadband X-ray spectra available today fails to enable us to statistically distinguish between jet models (Markoff et al 2005;Maitra et al 2009) and thermal and/or hybrid Comptonization in a corona (e.g., Coppi 1999Coppi , 2004. The fluorescent Fe Kα line and a reflection hump point towards a contribution by reflection, independent of the origin of the continuum (see Reynolds & Nowak 2003; for a review and Duro et al 2011;Tomsick et al 2014, and references therein for Cyg X-1).…”

No signatures of black hole spin in the X-ray spectrum of the Seyfert 1 galaxy Fairall 9

“…The analysis of these data is complicated because the effective area and spectral response function calculations are compromised. Although Lohfink et al (2012a) proceeded to analyse the data by creating a new attitude solution (as described in Nowak et al 2011), the software tool that generates the effective area for spectral response functions, XISSIMARFGEN, was not designed to handle such large excursions in attitude (see Ishisaki et al 2007 for a detailed description of XISSIMARFGEN). The resulting errors in the effective area are unquantified.…”