CLEARING OUT A GALAXY

Journal Article · Wed Feb 15 04:00:00 EST 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/745/2/L34· OSTI ID:22048064

Zubovas, Kastytis; King, Andrew ^[1]

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1. Theoretical Astrophysics Group, University of Leicester, Leicester LE1 7RH (United Kingdom)

It is widely suspected that active galactic nucleus (AGN) activity ultimately sweeps galaxies clear of their gas. We work out the observable properties required to achieve this. Large-scale AGN-driven outflows should have kinetic luminosities {approx}{eta} L{sub Edd}/2 {approx} 0.05 L{sub Edd} and momentum rates {approx}20 L{sub Edd}/c, where L{sub Edd} is the Eddington luminosity of the central black hole and {eta} {approx} 0.1 its radiative accretion efficiency. This creates an expanding two-phase medium in which molecular species coexist with hot gas, which can persist after the central AGN has switched off. This picture predicts outflow velocities {approx}1000-1500 km s{sup -1} and mass outflow rates up to 4000 M{sub Sun} yr{sup -1} on kpc scales, fixed mainly by the host galaxy velocity dispersion (or equivalently black hole mass). All these features agree with those of outflows observed in galaxies such as Mrk231. This strongly suggests that AGN activity is what sweeps galaxies clear of their gas on a dynamical timescale and makes them red and dead. We suggest future observational tests of this picture.

• OSTI ID: 22048064
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 745; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
ASTROPHYSICS
BLACK HOLES
EFFICIENCY
GALAXIES
GALAXY NUCLEI
LUMINOSITY
MASS
QUASARS
STAR EVOLUTION
STAR MODELS
VELOCITY