Black hole winds II: Hyper-Eddington winds and feedback

Abstract

We show that black holes supplied with mass at hyper-Eddington rates drive outflows with mildly sub-relativistic velocities. These are ∼0.1-0.2c for Eddington accretion factorsṁ acc ∼ 10-100, and ∼1500 km s −1 forṁ acc ∼ 10 4 . Winds like this are seen in the X-ray spectra of ultraluminous sources (ULXs), strongly supporting the view that ULXs are stellar-mass compact binaries in hyper-Eddington accretion states. SS433 appears to be an extreme ULX system (ṁ acc ∼ 10 4 ) viewed from outside the main X-ray emission cone. For less-extreme Eddington factorsṁ acc ∼ 10-100 the photospheric temperatures of the winds are ∼100 eV, consistent with the picture that the ultraluminous supersoft sources (ULSs) are ULXs seen outside the medium-energy X-ray beam, unifying the ULX/ULS populations and SS433 (actually a ULS but with photospheric emission too soft to detect). For supermassive black holes (SMBHs), feedback from hyper-Eddington accretion is significantly more powerful than the usual near-Eddington ('UFO') case, and if realized in nature would imply M − σ masses noticeably smaller than observed. We suggest that the likely warping of the accretion disc in such cases may lead to much of the disc mass being expelled, severely reducing the incidence of such strong feedback. We show that hyper-Eddington feedback from bright ULXs can have major effects on their host galaxies. This is likely to have important consequences for the formation and survival of small galaxies.Key words: black hole physics -galaxies: active -quasars: general -quasars: supermassive black holes -galaxies: Seyfert -X-rays: binaries. I N T RO D U C T I O NIt is now widely accepted that winds driven by accretion on to black holes have major effects on their surroundings. Wide-angle winds from supermassive black holes (SMBH) in galaxy centres are probably the origin of the SMBH -galaxy scaling relations (for reviews of observations and theory see Kormendy & Ho 2013;King & Pounds 2015). King & Pounds (2003) gave a simple picture of black hole winds for the case when accretion on to the black hole is close to the Eddington value. This paper extends this to cover cases where the hole's mass supply rate is much larger. Shakura & Sunyaev (1973) set out a general theoretical picture of disc winds. They considered accretion discs where the mass supply at the outer edge would be super-Eddington near the black hole. At large distances from the hole, gas spirals inwards through an accretion disc and radiation pressure is unimportant. It first becomes E-mail: ark@astro.le.ac.uk significant in the disc at the spherization radius R sph , where the local energy release GMṀ/R sph is of order the Eddington luminositywith M the black hole mass,Ṁ the instantaneous accretion rate, and κ the electron scattering opacity. Some of the accreting gas is driven out as a wind by radiation pressure, and Shakura & Sunyaev assumed that this occurs at all disc radii R < R sph in such a way that GMṀ(R)/R ∼ L Edd at all R. This means that the accretion rate through the disc decr...

Extreme quasars at high redshift

“…The large outflow radial velocity (the average c( 1 2 ) of the blue shifted component is close to ∼ −4000 km s −1 ), as well as the high fraction of the blue shifted component to the total Civλ1549 luminosity (∼ 0.45, Sect. §5.4) ensure the maximization of the quasar mechanical feedback even if W Civλ1549 is in general relatively low (c.f., King & Muldrew 2016). The ra-tio˙ /L ∼ 0.01 comes close to the threshold value for exerting significant mechanical feedback on the entire host galaxies especially if the quasar is radiating at high Eddington ratio and at high luminosity (e.g., King & Pounds 2015, and references therein).…”

Nature of the Soft Ulx in NGC 247: Super-Eddington Outflow and Transition Between the Supersoft and Soft Ultraluminous Regimes

“…In supercritical accretion models, massive outflows are a key feature predicted by theories and numerical simulations (King & Pounds 2003;Poutanen et al 2007;Dotan & Shaviv 2011;Ohsuga & Mineshige 2011;Kawashima et al 2012;Jiang et al 2014;King & Muldrew 2016). Observationally, the detection of soft X-ray spectral residuals (Middleton et al 2014(Middleton et al , 2015b and emission/absorption lines (Pinto et al 2016) in ULXs have been argued as a signature of outflows associated with supercritical accretion.…”

“…It has been proposed that the The Astrophysical Journal, 831:117 (13pp), 2016 November 10 doi:10.3847/0004-637X/831/2/117 soft spectrum of soft ULXs could be emission from the photosphere of optically thick outflows, which obscure or soften the hard emission from the inner disk (Feng & Soria 2011;Shen et al 2015;King & Muldrew 2016;Soria & Kong 2016). King & Muldrew (2016) suggest that the soft ULXs and broadband ULXs are the same type of objects viewed at different angles. Urquhart & Soria (2016) suggest that the soft ULXs could be a special state of the normal ULXs; they may transition to be broadband ULXs when the photosphere becomes smaller and hotter (kT 150 bb eV).…”

Predicting ultraluminous X-ray source demographics from geometrical beaming

“…The combined loss of material into a wind (see Poutanen et al 2007;King & Muldrew 2016) and inwards radial advection (e.g. Abramowicz et al 1988) can cool the flow, thereby keeping it locally Eddington limited and yields a total radiative luminosity of ∼ L Edd (1 + lnṁ0) (Poutanen et al 2007).…”