A Simple Comptonization Model

By J. Steiner, Ramesh Narayan, J. E. McClintock, K. Ebisawa. 2008

211 citations recorded by the source corpus.

We present an empirical model of Comptonization for fitting the spectra of X-ray binaries. This model, named simpl, has been developed as a package implemented in XSPEC. With only two free parameters, simpl is competitive as the simplest model of Compton scattering. Unlike the pervasive standard power-law model, simpl incorporates the basic features of Compton scattering of soft photons by energetic coronal electrons. Using a simulated spectrum, we demonstrate that simpl closely matches the behavior of physical Comptonization models that consider the effects of optical depth, coronal electron temperature, and geometry. We present fits to RXTE spectra of the black hole transient H1743–322 and a BeppoSAX spectrum of LMC X–3 using both simpl and the standard power-law model. A comparison of the results shows that simpl gives equally good fits, while eliminating the troublesome divergence of the standard power-law model at low energies. simpl is completely flexible and can be used self-consistently with any seed spectrum of photons. We show an example of how simpl—unlike the standard power law—teamed up with diskbb (the standard model of disk accretion) provides a uniform disk normalization that is unaffected by moderate Comptonization.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/69d17925731e100146f6e3b188f9034b96c0cc6f

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Citations in the corpus

Swift J1644+57 gone MAD: the case for dynamically-important magnetic flux threading the black hole in a jetted tidal disruption event (2013, background): “1; by more than two orders of magnitude) can thus plausibly be associated with the point at which Ṁ ∼ 0.3ṀEdd (Steiner et al. 2009, 2010; Abramowicz et al. 2010).”
A physical model of the broad-band continuum of AGN and its implications for the UV/X relation and optical variability (2018, background): “These often show spectra at Lbol/LEdd ∼ 0.1–0.2 which are dominated by the thermal accretion disc emission, with only a small tail to higher energies from a hot Comptonisating corona (e.g., Kubota, Makishima, & Ebisawa 2001; Gierliński & Done 2004a; Steiner et al. 2009).”
An Embedded X-Ray Source Shines through the Aspherical AT 2018cow: Revealing the Inner Workings of the Most Luminous Fast-evolving Optical Transients (2018, methodology): “Fitting the broadband X-ray data of AT 2018cow at δt= 7.7 days with a Comptonized disk-reflection model via simpl (Steiner et al. 2009) acting on a thermal component and relxill (Dauser et al. 2014) produces a good fit to the data ( d.o.f. 1.02c ~ ), matching a kTe 30 keV corona, with reflection…”
Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets (2013, methodology): “While it is essential to select spectra that have a substantial thermal component (i.e., f SC < ∼ 25%; Steiner et al. 2009a), it is equally important to select data of moderate luminosity, speciﬁcally spectra with Eddington-scaled disk luminosities L/L Edd < 0 .”
A PARALLAX DISTANCE TO THE MICROQUASAR GRS 1915+105 AND A REVISED ESTIMATE OF ITS BLACK HOLE MASS (2014, methodology): “…where J and M are the angular momentum and mass of the black hole, respectively, and |a∗| 1. criteria (e.g., Steiner et al. 2011): goodness of fit (χ2ν < 2), lowto-moderate luminosity (Ldisk < 0.3 LEddington), and a dominant thermal component with scattering fraction <25% (Steiner et al. 2009a).”
THE CONSTANT INNER-DISK RADIUS OF LMC X-3: A BASIS FOR MEASURING BLACK HOLE SPIN (2010, methodology): “…(third family), one sees that our results are essentially identical whether one uses our baseline upscatteringonly model simpl ≡simpl-1 or a two-sided scattering model simpl-2 (Steiner et al. 2009a), while the results obtained using the standard power-law model powerlaw differ only modestly ( 5%).”
THE EXTREME SPIN OF THE BLACK HOLE IN CYGNUS X-1 (2011, methodology): “In addition to DISKBB, each model includes (i) a Compton power-law component, eitherCOMPBB (Nishimura et al. 1986) orSIMPLR (Steiner et al. 2009b, 2011) convolved withDISKBB, and (ii) a reflection componentPEXRIV (Magdziarz & Zdziarski 1995)27, which models the absorption edges, plus an Fe Kα…”
Measuring the spins of accreting black holes (2011, methodology): “Now, however, using our improved methodologies (Steiner et al 2009a, 2010b), we are able to obtain useful and consistent values of spin as well for spectra that have a strong Compton component of emission, like the one shown in the right panel of figure 6.”
The spin of the black hole microquasar XTE J1550−564 via the continuum-fitting and Fe-line methods (2010, methodology): “However, we now introduce a modified version of SIMPL that is appropriate when including a separate and additive reflection component.”