An Extended Scheme for Fitting X-Ray Data with Accretion Disk Spectra in the Strong Gravity Regime

By M. Dovc̆iak, V. Karas, T. Yaqoob. 2004

213 citations recorded by the source corpus.

Accreting black holes are believed to emit X-rays, which then mediate information about strong gravity in the vicinity of the emission region. We report on a set of new routines for the XSPEC package for analyzing X-ray spectra of black-hole accretion disks. The new computational tool significantly extends the capabilities of the currently available fitting procedures that include the effects of strong gravity and allows one to systematically explore the constraints on more model parameters than previously possible (e.g., black-hole angular momentum). Moreover, axial symmetry of the disk intrinsic emissivity is not assumed, although it can be imposed to speed up the computations. The new routines can be used also as a stand-alone and flexible code with the capability of handling time-resolved spectra in the regime of strong gravity. We have used the new code to analyze the mean X-ray spectrum from the long XMM-Newton 2001 campaign of the Seyfert 1 galaxy MCG -6-30-15. Consistent with previous findings, we obtained a good fit to the broad Fe K line profile for a radial line intrinsic emissivity law in the disk that is not a simple power law, and for near maximal value of black hole angular momentum. However, equally good fits can be obtained also for small values of the black hole angular momentum. The code has been developed with the aim of allowing precise modeling of relativistic effects. Although we find that current data cannot constrain the parameters of black-hole/accretion disk system well, the code allows, for a given source or situation, detailed investigations of what features of the data future studies should be focused on in order to achieve the goal of uniquely isolating the parameters of such systems.

Subfields: Astronomy and Astrophysics, Biomedical Engineering

View Paper: https://www.semanticscholar.org/paper/3584b193fecf39f18fa415a6354c7fa8c16a2d82

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Citations in the corpus

IMPROVED REFLECTION MODELS OF BLACK HOLE ACCRETION DISKS: TREATING THE ANGULAR DISTRIBUTION OF X-RAYS (2013, background): “Beckwith & Done (2004) and Dovčiak et al. (2004) presented similar calculations emphasizing how the assumed angular emissivity law (limb darkening or brightening) can significantly affect the line profile when relativistic effects are important.”
Understanding X‐ray reflection emissivity profiles in AGN: locating the X‐ray source (2012, background): “Dovčiak et al. (2004) present an extended framework for fitting the spectral profiles of relativistically broadened emission lines with a suite of models including kyline which can either assume an emissivity profile taking form of a power law or take a tabulated radial emissivity profile for the…”
Polarimetry of near-infrared flares from Sagittarius A* (2006, methodology): “The calculations have been carried out using the code by Dovciak et al. (2004).”
Constraining Black Hole Spin via X-Ray Spectroscopy (2006, methodology): “…power of broad iron lines for spin determination, wemodeled the 2Y10 keV EPIC pn as a simple power-law continuum modified by a broad iron line (and absorption by the Galactic column of 4:1 ; 1020 cm 2 toward this source); this is comparable to the study performed by Dovčiak et al. (2004).”
Relativistic X-Ray Lines from the Inner Accretion Disks Around Black Holes (2007, background): “Some studies have concluded that relativistic disk lines cannot serve as good indicators of black hole spin, because the nature of emission within the plunging region is uncertain and may serve to give faulty information on the ISCO (see, e.g., Dovciak et al. 2004).”
Broad emission lines for a negatively spinning black hole (2010, background): “…(1997) and Schnittman (2006), none of the currently available models for relativistic lines such asdiskline (Fabian et al. 1989), laor (Laor 1991),kerrdisk (Brenneman & Reynolds 2006), or theky-family of models (Dovčiak et al. 2004) are valid for black holes with retrograde accretion discs.”
X-Ray Properties of Black-Hole Binaries (2006, methodology): “…more widely and with some confidence, namely: (1) models of thin accretion disks are now publicly available in XSPEC (“KERRBB”, Li et al. 2005; “KY”, Dovčiak et al. 2004) that include all relativistic effects and allow one to fit for a∗; and (2) sophisticated disk atmosphere models now exist…”
X-RAY REFLECTED SPECTRA FROM ACCRETION DISK MODELS. III. A COMPLETE GRID OF IONIZED REFLECTION CALCULATIONS (2013, background): “…a skewed line profile with a red wing that can extend to very low energies, particularly in the case of high spin (e.g., Fabian et al. 2000; Fabian & Vaughan 2003; Reynolds & Nowak 2003; Dovčiak et al. 2004; Miller et al. 2008; Steiner et al. 2011; Reynolds et al. 2012; Dauser et al. 2012).”
The Masses and Spins of Neutron Stars and Stellar-Mass Black Holes (2014, background): “Thus with a simple relativistic smearing model (usually just a library of rays traced from close to the black hole to infinity; see [247, 248, 249, 250, 251, 252]) the spin can be measured in sensitive X-ray spectra (see, e.”
TESTING THE NO-HAIR THEOREM WITH OBSERVATIONS IN THE ELECTROMAGNETIC SPECTRUM. IV. RELATIVISTICALLY BROADENED IRON LINES (2012, unknown): “…relativity, these line profiles can be used to measure the spins of black holes (Fabian et al. 1989; Stella 1990; Laor 1991; Reynolds & Nowak 2003; Dovčiak et al. 2004; Beckwith & Done 2004, 2005; Brenneman & Reynolds 2006; Reynolds & Fabian 2008; Dexter & Agol 2009; Karas & Sochora 2010; Dauser…”