Supercritically accreting stellar mass black holes as ultraluminous X-ray sources

By J. Poutanen, G. Lipunova, S. Fabrika, A. Butkevich, P. Abolmasov. 2006

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We derive the luminosity‐temperature relation for the supercritically accreting black holes (BHs) and compare it to the data on ultraluminous X-ray sources (ULXs). At super-Eddington accretion rates, an outflow forms within the spherization radius. We construct the accretion disc model accounting for the advection and the outflow, and compute characteristic disc temperatures. The bolometric luminosity exceeds the Eddington luminosity LEdd by a logarithmic factor 1 + 0. 6l n˙ m (where ˙ m is the accretion rate in Eddington units) and the wind kinetic luminosity is close to LEdd. The apparent luminosity for the face-on observer is 2‐7 times higher because of geometrical beaming. Such an observer has a direct view of the inner hot accretion disc, which has a peak temperature Tmax of a few keV in stellar mass BHs. The emitted spectrum extends as a power law FE ∝ E −1 down to the temperature at the spherization radius Tsp ≈ ˙ m −1/2 keV. We associate T max with a few keV spectral components and Tsp with the soft, 0.1‐0.2 keV components observed in ULXs. An edge-on observer sees only the soft emission from the extended envelope, with the photosphere radius exceeding the spherization radius by orders of magnitude. The dependence of the photosphere temperature on luminosity is consistent with that observed in the super-Eddington accreting BHs SS 433 and V4641 Sgr. Strong outflows combined with the large intrinsic X-ray luminosity of the central BH explain naturally the presence of the photoionized nebulae around ULXs. An excellent agreement between the model and the observational data strongly argues in favour of ULXs being supercritically accreting, stellar mass BHs similar to SS 433, but viewed close to the symmetric axis.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/ff881ea87a8e6598c046016290646efa47490d26

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Citations in the corpus

Hot Accretion Flows Around Black Holes (2014, background): “Equations (2)–(4) should also be modified when there is mass outflow (e.g., Poutanen et al. 2007, Xie & Yuan 2008).”
The ultraluminous state revisited: fractional variability and spectral shape as diagnostics of super-Eddington accretion (2013, background): “…by guest on 29 July 2018 both regimes are produced in a single type of system, with the observed characteristics of the source being dependent on both accretion rate and – critically – the inclination of the ULX system (cf. Poutanen et al. 2007).”
On the maximum accretion luminosity of magnetized neutron stars: connecting X-ray pulsars and ultraluminous X-ray sources (2015, background): “The problem is that at high accretion rate the accretion disc may become locally super-Eddington outside of the magnetosphere producing strong outflows (Shakura & Sunyaev 1973; Poutanen et al. 2007) and reducing the NS luminosity.”
Numerical simulations of super-critical black hole accretion flows in general relativity (2013, background): “Radiative energy trapped in the gas may contribute to its thermal and kinetic energy before the gas expands enough to become optically thin and release the photons (Poutanen et al. 2007).”
Growth of Structure Seeded by Primordial Black Holes (2006, background): “On the basis of the observed ULX luminosities of 1039 erg s 1, stellar-mass black holes are ruled out unless the emission is highly beamed; there is at present no evi- dence for beaming (Mushotzky 2004; Freeland et al. 2006; Poutanen et al. 2007; Miniutti et al. 2006).”
The evolution of massive black holes and their spins in their galactic hosts (2012, background): “However, following the theory of thin accretion disks (Shakura & Sunyaev (1973); see also Poutanen et al. (2007)), we assume the MBH’s bolometric luminosity to be Lbh,QSO = min { η(abh)ṀQSOc 2, LEdd [ 1 + ln ( η(abh)ṀQSOc 2 LEdd )]} .”
BlackCAT: A catalogue of stellar-mass black holes in X-ray transients (2015, background): “The source of these luminosities is still uncertain, and it has been proposed that they may be produced by intermediate mass BHs (∼103 M , see e.g. Miller et al. 2003) or stellar-mass BHs (e.g., Poutanen et al. 2007; Kawashima et al. 2012).”
A COMPLETE SAMPLE OF ULTRALUMINOUS X-RAY SOURCE HOST GALAXIES (2011, background): “…models are not appropriate and have to be replaced by geometrically thicker disks (e.g., slim disks; Abramowicz et al. 1988; Kawaguchi 2003; Poutanen et al. 2007; Gladstone et al. 2009) with massive outflows.5 This introduces the possibility of mild geometrical beaming inside a conical…”
The Ultraluminous State (2009, methodology): “These winds will become increasingly important as the flows become increasingly super-Eddington, completely enveloping the inner regions of the disc-corona out to an increasing photospheric radius (as in SS 433, Poutanen et al. 2007).”
DISCOVERY OF COHERENT PULSATIONS FROM THE ULTRALUMINOUS X-RAY SOURCE NGC 7793 P13 (2016, background): “…have been thought to harbor black holes with masses ranging from M ∼ 10 M , consistent with a stellar remnant accreting above the Eddington rate (e.g., Poutanen et al. 2007; Middleton et al. 2015), to intermediate mass BHs (M ∼ 102−5 M ; e.g., Miller et al. 2004) in a sub-Eddington disk accretion…”
Ultraluminous X-ray sources in the Chandra and XMM-Newton era (2011, methodology): “It is suggested that supercritical accretion may produce massive outflows, which are optically thick with soft, thermal emission at similar temperature, being another possible originfor the detected soft excesses (King 2004; Begelman et al. 2006; Poutanen et al. 2007).”
Modelling the behaviour of accretion flows in X-ray binaries (2007, background): “However, the clear signatures of mass loss seen from this system (Kotani et al. 2000; Lee et al. 2002) also point to additional cooling from winds being important, as expected for L ≥ LEdd (e.g. Shakura & Sunyaev 1973; Begelman et al 2006; Ohsuga 2006; 2007; Poutanen et al. 2007).”