Investigating the properties of AGN feedback in hot atmospheres triggered by cooling-induced gravitational collapse

Abstract

Radiative cooling may plausibly cause hot gas in the centre of a massive galaxy, or galaxy cluster, to become gravitationally unstable. The subsequent collapse of this gas on a dynamical timescale can provide an abundant source of fuel for AGN heating and star formation. Thus, this mechanism provides a way to link the AGN accretion rate to the global properties of an ambient cooling flow, but without the implicit assumption that the accreted material must have flowed onto the black hole from 10s of kiloparsecs away. It is shown that a fuelling mechanism of this sort naturally leads to a close balance between AGN heating and the radiative cooling rate of the hot, X-ray emitting halo. Furthermore, AGN powered by cooling-induced gravitational instability would exhibit characteristic duty cycles (delta) which are redolent of recent observational findings: delta is proportional to L_X/sigma_{*}^{3}, where L_X is the X-ray luminosity of the hot atmosphere, and sigma_{*} is the central stellar velocity dispersion of the host galaxy. Combining this result with well-known scaling relations, we deduce a duty cycle for radio AGN in elliptical galaxies that is approximately proportional to M_{BH}^{1.5}, where M_{BH} is the central black hole mass. Outburst durations and Eddington ratios are also given. Based on the results of this study, we conclude that gravitational instability could provide an important mechanism for supplying fuel to AGN in massive galaxies and clusters, and warrants further investigation.

Accepted for publication in MNRAS. 8 pages

References in corpus (12)

• On the prevalence of radio-loud AGN in brightest cluster galaxies: implications for AGN heating of cooling flows
• The Regulation of Cooling and Star Formation in Luminous Galaxies by AGN Feedback and the Cooling-Time/Entropy Threshold for the Onset of Star Formation
• An Entropy Threshold for Strong H-alpha and Radio Emission in the Cores of Galaxy Clusters
• Simulations of AGN feedback in galaxy clusters and groups: impact on gas fractions and the Lx-T scaling relation
• The duty cycle of local radio galaxies
• AGN self-regulation in cooling flow clusters
• Simulations of cosmic ray feedback by AGN in galaxy clusters
• Measuring the accretion rate and kinetic luminosity functions of supermassive black holes
• Combining Semi-analytic Models with Simulations of Galaxy Clusters: the Need for Heating from Active Galactic Nuclei
• The Source of Mass Accreted by the Central Black Hole in Cooling Flow Clusters
• Observable consequences of kinetic and thermal AGN feedback in elliptical galaxies and galaxy clusters
• Heating Cluster Gas

Cited by in corpus (15)

• Morphologies of z~0.7 AGN Host Galaxies in CANDELS: No trend of merger incidence with AGN luminosity
• The Energetics and Lifetimes of Local Radio Active Galactic Nuclei
• The duty cycle of radio galaxies revealed by LOFAR: remnant and restarted radio source populations in the Lockman Hole
• Size dependence of the radio luminosity - mechanical power correlation in radio galaxies
• The Australia Telescope Large Area Survey: Spectroscopic Catalogue and Radio Luminosity Functions
• The prevalence of AGN feedback in massive galaxies at z~1
• Delayed triggering of radio Active Galactic Nuclei in gas-rich minor mergers in the local Universe
• IGM Heating in Fossil Galaxy Groups
• Measuring the jet power of flat spectrum radio quasars
• Radio Galaxy Zoo: Observational evidence for environment as the cause of radio source asymmetry
• RAiSE X: searching for radio galaxies in X-ray surveys
• RAiSERed: radio continuum redshifts for lobed AGNs
• CosmoDRAGoN simulations -- I. Dynamics and observable signatures of radio jets in cosmological environments
• Central radio galaxies in galaxy clusters: Joint surveys by eROSITA and ASKAP
• Why and when is internally-driven AGN feedback energetically favoured?