Abstract
We have compared the 2001 XMM-Newton spectra of the stellar mass black hole binary XTE J1650-500 and the active galaxy MGC-6-30-15, focusing on the broad, excess emission features at ~4--7 keV displayed by both sources. Such features are frequently observed in both low mass X-ray binaries and active galactic nuclei. For the former case it is generally accepted that the excess arises due to iron emission, but there is some controversy over whether their width is partially enhanced by instrumental processes, and hence also over the intrinsic broadening mechanism. Meanwhile, in the latter case, the origin of this feature is still subject to debate; physically motivated reflection and absorption interpretations are both able to reproduce the observed spectra. In this work we make use of the contemporaneous BeppoSAX data to demonstrate that the breadth of the excess observed in XTE J1650-500 is astrophysical rather than instrumental, and proceed to highlight the similarity of the excesses present in this source and MGC-6-30-15. Both optically thick accretion discs and optically thin coronae, which in combination naturally give rise to relativistically-broadened iron lines when the disc extends close to the black hole, are commonly observed in both class of object. The simplest solution is that the broad emission features present arise from a common process, which we argue must be reflection from the inner regions of an accretion disc around a rapidly rotating black hole; for XTE J1650-500 we find spin constraints of 0.84 < a* < 0.98 at the 90 per cent confidence level. Other interpretations proposed for AGN add potentially unnecessary complexities to the theoretical framework of accretion in strong gravity.
Highlights
Simple models for the accretion of material on to a black hole usually include two physically distinct components
For the black holes associated with X-ray binaries (XRBs; MBH ∼ 10 M ) the discs are relatively hot and the thermal emission should be observed in the X-ray band at ∼0.2–1.0 keV, while the discs around the much larger black holes associated with active galactic nuclei (AGNs; MBH 106 M ) are much cooler and should be observed in the ultraviolet (UV)
We model the continuum of XTE J1650−500 with the standard black hole binaries (BHBs) components, namely a multi-colour blackbody accretion disc which accounts for the thermal emission from the disc and dominates at soft energies, and a power law, associated with Comptonization of the thermal emission by electrons in a corona, which dominates at hard energies
Summary
Simple models for the accretion of material on to a black hole (of any mass) usually include two physically distinct components. High-quality X-ray spectroscopy of XRBs has revealed the presence of broad excesses over the Comptonized continuum in the ∼4.0–8.0 keV energy range, which are again frequently interpreted as relativistically broadened iron emission lines, e.g. XTE J1650−500 (Miller et al 2002, Miniutti, Fabian & Miller 2004), GX 339−4 (Reis et al 2008), GRS 1915+105 (Blum et al 2009), Swift J1753.5−0127 (Reis et al 2009a), XTE J1752−223 (Reis et al 2011). High-energy features consistent with the Compton Hump are frequently observed in black hole binaries (BHBs; see e.g. Reis, Fabian & Miller 2010b), supporting the theory that X-ray reflection is present in these sources. This work is structured as follows: Section 2 gives details on the data reduction; Section 3 presents our spectral analysis, highlighting the similarity of the two line profiles and Section 4 presents our discussion, in which we use this comparison as the basis for a simple, logical argument in favour of the reflection interpretation for AGN
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
