Broad Iron-Kα Emission Lines as a Diagnostic of Black Hole Spin

By C. Reynolds, A. C. Fabian. 2007

173 citations recorded by the source corpus.

We address the ability of broad iron emission lines from black hole accretion disks to diagnose the spin of the black hole. Using a high-resolution three-dimensional MHD simulation of a geometrically thin accretion disk in a pseudo-Newtonian potential, we show that both the mid-plane density and the vertical column density of the accretion flow drop dramatically over a narrow range of radii close to the innermost stable circular orbit (ISCO). We argue that this drop of density is accompanied by a sharp increase in the ionization parameter of the X-ray photosphere, and that the resulting imprint of the ISCO on the X-ray reflection spectrum can be used to constrain spin. Motivated by this simulation, we construct a simplified toy model of the accretion flow within the ISCO of a Kerr black hole, and use this model to estimate the systematic error on inferred black hole spin that may result from slight bleeding of the iron line emission to the region inside of the ISCO. We find that these systematic errors can be significant for slowly spinning black holes but become appreciably smaller as one considers more rapidly rotating black holes.

Subfields: Astronomy and Astrophysics, Biomedical Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/4d892823c1a2a46e2e86c74302dcb213b180f36e

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Biomedical Engineering

In Mechanical Engineering

Citations in the corpus

Simulations of magnetized discs around black holes: Effects of black hole spin, disc thickness and magnetic field geometry (2010, methodology): “Simulations of thin discs using a pseudo-Newtonian potential for the BH reveal good agreement with standard thin disc theory (Reynolds & Fabian 2008).”
Three-dimensional general relativistic radiation magnetohydrodynamical simulation of super-Eddington accretion, using a new code HARMRAD with M1 closure (2013, background): “Simulations have only so-far included an ad hoc cooling function that leads to |H/R| ∼ 0.05–0.1 (Shafee et al. 2008; Reynolds & Fabian 2008; Reynolds & Miller 2009; Noble et al. 2009; Penna et al. 2010; Noble et al. 2010; Sorathia et al. 2010; Noble et al. 2011b; Beckwith et al. 2011).”
THE CONSTANT INNER-DISK RADIUS OF LMC X-3: A BASIS FOR MEASURING BLACK HOLE SPIN (2010, background): “…simulations provide support for identifying the inner-disk radius Rin with the radius of the innermost stable circular orbit RISCO (Reynolds & Fabian 2008; Shafee et al. 2008; Penna et al. 2010; but see Noble et al. 2009), a proposition that has a long history of theoretical and…”
THE RADIATIVE EFFICIENCY OF ACCRETION FLOWS IN INDIVIDUAL ACTIVE GALACTIC NUCLEI (2010, background): “…angle of the AD emission, (Connors et al. 1980; Laor et al. 1990; Dovčiak et al. 2008; Schnittman & Krolik 2009), and the profile of lines emitted by the AD (Fabian et al. 1989; Kojima 1991; Laor 1991; Dabrowski et al. 1997; Beckwith & Done 2004; Brenneman & Reynolds 2006; Reynolds & Fabian 2008).”
STELLAR-MASS BLACK HOLE SPIN CONSTRAINTS FROM DISK REFLECTION AND CONTINUUM MODELING (2009, methodology): “Based on the results summarized in Reynolds & Fabian (2008) and related work by Shafee et al. (2008), a conservative estimate of the uncertainty in the ISCO based on this and other simulations is 0.5 rg for low spin parameters (an uncertainty of about 20% for very low spin; see Miniutti & Fabian…”
THE SPIN OF THE SUPERMASSIVE BLACK HOLE IN NGC 3783 (2011, background): “Assuming that the region within the general relativistic radius of marginal stability does not contribute to the reflection spectrum (Reynolds & Fabian 2008) we determine a lower limit of a 0.98 (90% confidence) to the dimensionless spin parameter of the black hole.”
Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy (2013, background): “This basic behavior is confirmed by magnetohydrodynamic simulations of thin accretion disks (Reynolds & Fabian 2008; Penna et al. 2010).”
The Masses and Spins of Neutron Stars and Stellar-Mass Black Holes (2014, background): “Currently, the most convincing relativistic line profile and best data are from an observation of Serpens X-1 with NuSTAR, which give rNS ≤ 15 km (and thus a surface redshift zNS ≥ 0.16 for MNS = 1.4 M⊙) for a broad set of fits, and rNS ≤ 12.6 km if the disk extends to the ISCO ([283]).”
Hot Accretion Flows Around Black Holes (2014, result): “These observations have been used to argue that the thin disk is not truncated but extends down to the ISCO (e.g., Miller et al. 2006, Rykoff et al. 2007, Ramadevi & Seetha 2007, Reis et al. 2010).”
Semi-implicit scheme for treating radiation under M1 closure in general relativistic conservative fluid dynamics codes (2012, background): “…of thin discs have been computed so far, and all are based on an ad hoc (although physically motivated) local cooling function which artificially removes excess heat to keep the disc geometrically thin (Shafee et al. 2008; Penna et al. 2010; Noble et al. 2011; see also Reynolds & Fabian 2008).”
THE EXTREME SPIN OF THE BLACK HOLE IN CYGNUS X-1 (2011, unknown): “Strong theoretical support for identifyingRin with RISCO is provided by magnetohydrodynamic simulations of thin accretion disks, which show the disk emission falling off rapidly inside the ISCO (Shafee et al. 2008; Reynolds & Fabian 2008; Penna et al. 2010; Kulkarni et al. 2011; Noble et al. 2010).”
The spin of the black hole microquasar XTE J1550−564 via the continuum-fitting and Fe-line methods (2010, methodology): “Theoretical support for identifying Rin with RISCO is provided by magnetohydrodynamic simulations of thin accretion discs (Reynolds & Fabian 2008; Shafee et al. 2008; Penna et al. 2010; Kulkarni et al. 2011; but see Noble, Krolik & Hawley 2009, 2010).”
TESTING THE NO-HAIR THEOREM WITH OBSERVATIONS IN THE ELECTROMAGNETIC SPECTRUM. IV. RELATIVISTICALLY BROADENED IRON LINES (2012, background): “Therefore, the spin of the black hole can be measured directly from the position of the ISCO, even if other important parameters of the black hole, such as its mass or distance, are unknown (e.g., Reynolds & Nowak 2003; Brenneman & Reynolds 2006; Reynolds & Fabian 2008).”
Understanding X‐ray reflection emissivity profiles in AGN: locating the X‐ray source (2012, background): “…regions of the accretion disc, not least the innermost extent of the disc which is used to infer the spin of the central black hole, assuming the accretion disc extends down to the innermost stable orbit (Reynolds & Fabian 2008) or to infer truncation of the accretion disc before this point.”
Broad emission lines for a negatively spinning black hole (2010, background): “…with systematic effects due to the high count rate of Galactic sources (Yamada et al. 2009; Done & Diaz Trigo 2010) and due to the uncertainty of the parameters of the underlying continuum (e.g., Ross & Fabian 2007; Reynolds & Fabian 2008) currently dominating the uncertainty of the measurements.”
Three-Dimensional Simulations of Magnetized Thin Accretion Disks around Black Holes: Stress in the Plunging Region (2008, background): “The one exception is the recent work of Reynolds & Fabian (2008) who considered a thin disk with h/r ∼ 0.05 in a pseudo-Newtonian potential.”
Measuring the spins of accreting black holes (2011, methodology): “A number of recent studies of magnetized disks using three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations have explored this question (Shafee et al 2008a, Reynolds and Fabian 2008, Noble and Krolik 2009, Noble et al 2010, Penna et al 2010).”