Quasar feedback: more bang for your buck

By P. Hopkins, M. Elvis. 2009

396 citations recorded by the source corpus.

We propose a ‘two-stage’ model for the effects of feedback from a bright quasar on the cold gas in a galaxy. It is difficult for winds or other forms of feedback from near the accretion disc to directly impact (let alone blow out of the galaxy) dense molecular clouds at ∼kpc. However, if such feedback can drive a weak wind or outflow in the hot, diffuse interstellar medium (a relatively ‘easy’ task), then in the wake of such an outflow passing over a cold cloud, a combination of instabilities and simple pressure gradients will drive the cloud material to effectively expand in the direction perpendicular to the incident outflow. This shredding/expansion (and the corresponding decrease in density) may alone be enough to substantially suppress star formation in the host. Moreover, such expansion, by even a relatively small factor, dramatically increases the effective cross-section of the cloud material and makes it much more susceptible to both ionization and momentum coupling from absorption of the incident quasar radiation field. We show that even a moderate effect of this nature can dramatically alter the ability of clouds at large radii to be fully ionized and driven into a secondary outflow by radiation pressure. Since the amount of momentum and volume which can be ionized by observed quasar radiation field is more than sufficient to affect the entire cold gas supply once it has been altered in this manner (and the ‘initial’ feedback need only initiate a moderate wind in the low-density hot gas), this reduces by an order of magnitude the required energy budget for feedback to affect a host galaxy. Instead of ∼5 per cent of the radiated energy (∼100 per cent momentum) needed if the initial feedback must directly heat or ‘blow out’ the galactic gas, if only ∼0.5 per cent of the luminosity (∼10 per cent momentum) can couple to drive the initial hot outflow, this mechanism could be efficient. This amounts to hot gas outflow rates from near the accretion disc of only ∼5–10 per cent of the black hole accretion rate.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/13b18cc94a0664c24ccfc942d39aaf4b431a4f38

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In Astronomy and Astrophysics

1. D. M. Alexander
2. P. Hopkins
3. L. Hernquist
4. R. Dav'e
5. R. Genzel
6. D. Lutz
7. R. Maiolino
8. E. Daddi

Citations in the corpus

• OUTFLOWS FROM ACTIVE GALACTIC NUCLEI: KINEMATICS OF THE NARROW-LINE AND CORONAL-LINE REGIONS IN SEYFERT GALAXIES, (2011, background): “…of the radiated luminosity Lbol of the AGN couples thermodynamically to the surrounding gas (∼5%; di Matteo et al. 2005), although recent work of Hopkins & Elvis (2010) demonstrates that a two-stage feedback model, similar to the scenario proposed in Section 5.5, requires a much lower energy…”
• Molecular line emission in NGC 1068 imaged with ALMA: I. An AGN-driven outflow in the dense molecular gas (2014, background): “This fraction is lowered to ∼ 0.5% in the two-phase feedback model of Hopkins & Elvis (2010b).”
• INTEGRAL FIELD SPECTROSCOPY OF MASSIVE, KILOPARSEC-SCALE OUTFLOWS IN THE INFRARED-LUMINOUS QSO Mrk 231 (2011, methodology): “Either (1) wide-angle winds from the AGN accretion disk or broad line region or (2) coupling of the AGN radiation to the dust in the wind are possible explanations (e.g., Crenshaw et al. 2003; Hopkins & Elvis 2010).”
• AGN outflows and feedback twenty years on (2018, neutral): “ variable) kinetic coupling efficiency calculated by Costa et al.[42]. The right panel shows coupling efficiencies employed by fiducial AGN feedback models, using the “quasar mode” value where applicable[71, 98, 99, 100, 77]. In these models, a 100% of the injected energy is unlikely to become kinetic ”
• MASSIVE MOLECULAR OUTFLOWS AND NEGATIVE FEEDBACK IN ULIRGs OBSERVED BY HERSCHEL-PACS (2011, background): “It is also unclear from the models whether it is possible to distinguish AGN driven outflows from stellar-driven outflows observationally (see, e.g., Hopkins & Elvis 2010).”
• Relativistic jet feedback in high-redshift galaxies – I. Dynamics (2016, background): “However, only a few papers have addressed the complex nature of the interaction of such winds with a dense multiphase interstellar medium (ISM; see for example Hopkins & Elvis 2010; Gabor & Bournaud 2014; Hopkins et al. 2016).”
• Gravitational torque-driven black hole growth and feedback in cosmological simulations (2016, background): “Kinetic AGN outflows can thus have a large impact even for energetic efficiencies as low as 0.1 per cent Lbol (Hopkins & Elvis 2010).”
• Unification of X-ray winds in Seyfert galaxies: from ultra-fast outflows to warm absorbers (2012, background): “In particular, the kinetic power of these UFOs is systematically higher than the minimum required by simulations of feedback induced by winds/outflows (e.g. Hopkins & Elvis 2010; Gaspari et al. 2011a, b, 2012b).”
• Quasar outflows and AGN feedback in the extreme UV: HST/COS observations of HE 0238−1904 (2013, background): “DISCUSSION Significant AGN feedback processes typically require a mechanical energy input of roughly 0.5–5% of the Eddington luminosity of the quasar (Hopkins & Elvis 2010; Scannapieco & Oh 2004, respectively).”
• Evidence of strong quasar feedback in the early Universe (2012, background): “…the bulk of their gas, therefore quenching star formation (Silk & Rees 1998; Granato et al. 2004; Di Matteo et al. 2005; Springel et al. 2005; Croton et al. 2006; Narayanan et al. 2008; Hopkins et al. 2008; Fabian et al. 2009; King 2010; King et al. 2011; Hopkins & Elvis 2010; Zubovas & King 2012).”
• Detection of HCN, HCO+, and HNC in the Mrk 231 molecular outflow. Dense molecular gas in the AGN wind (2011, background): “They suggest the AGN-driven two-phase model by Hopkins & Elvis (2010) as a possible scenario for the neutral wind of Mrk 231: Close to the center, the AGN acts on the hot interstellar medium, powering an outflow that causes the cold molecular clouds to expand, which makes them more susceptible to…”
• DRIVING OUTFLOWS WITH RELATIVISTIC JETS AND THE DEPENDENCE OF ACTIVE GALACTIC NUCLEUS FEEDBACK EFFICIENCY ON INTERSTELLAR MEDIUM INHOMOGENEITY (2012, methodology): “This acceleration mechanism of clouds found in our simulations may be interpreted as a variation of the two-stage feedback model proposed by Hopkins & Elvis (2010).”
• Enhanced star formation rates in AGN hosts with respect to inactive galaxies from PEP-Herschel observations (2012, background): “This ‘negative AGN feedback’ is necessary for theoretical models to reproduce many observations, such as the strong suppression of SF in the most massive galaxies (e.g. Di Matteo et al. 2005; Springel et al. 2005; Bower et al. 2006; Croton et al. 2006; Menci et al. 2008; Hopkins & Elvis 2010).”
• The Suzaku View of Highly Ionized Outflows in AGN. 1; Statistical Detection and Global Absorber Properties (2012, background): “…imparted by individual warm absorption components is very low, typically 0.01 per cent of an AGN’s bolometric luminosity (Lbol) (e.g. Blustin et al. 2005), which is significantly lower than the ∼0.5 per cent of Lbol thought necessary for feedback to affect the host galaxy (Hopkins & Elvis 2010).”
• Very extended cold gas, star formation and outflows in the halo of a bright QSO at z>6 (2014, background): “…Faucher-Giguère & Quataert 2012; Costa et al. 2014b and references therein), and the models invoking radiation pressure on dusty clouds as the main mechanism at the origin of galacticscale outflows (e.g. Hopkins & Elvis 2010; Fabian 2012; Roth et al. 2012; Thompson et al. 2014 and refs therein).”
• THE MULTIPHASE STRUCTURE AND POWER SOURCES OF GALACTIC WINDS IN MAJOR MERGERS (2013, methodology): “If an AGN drives the highest velocity flows in our sample, then the energy outflow rate in the wind is a small fraction of the AGN’s luminosity (0.1− 0.4%), comfortably within the requirements of recent models of AGN feedback (Hopkins & Elvis 2010; Faucher-Giguère et al. 2012).”
• Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population (2014, background): “…2012; Gabor & Bournaud 2014) which could make galactic-scale outflows driven from a nuclear star forming region or an AGN indistinguishable (see also Hopkins & Elvis 2010; Heckman et al. 2011 and Diamond-Stanic et al. 2012 for other reasons why it could be difficult to distinguish between AGN and…”