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Driving outflows with relativistic jets and the dependence of AGN feedback efficiency on interstellar medium inhomogeneity

Wagner, Alexander; Bicknell, Geoffrey; Umemura, M

Description

We examine the detailed physics of the feedback mechanism by relativistic active galactic nucleus (AGN) jets interacting with a two-phase fractal interstellar medium (ISM) in the kpc-scale core of galaxies using 29 three-dimensional grid-based hydrodynamical simulations. The feedback efficiency, as measured by the amount of cloud dispersal generated by the jet-ISM interactions, is sensitive to the maximum size of clouds in the fractal cloud distribution but not to their volume filling factor....[Show more]

dc.contributor.authorWagner, Alexander
dc.contributor.authorBicknell, Geoffrey
dc.contributor.authorUmemura, M
dc.date.accessioned2015-12-10T23:23:07Z
dc.identifier.issn0004-637X
dc.identifier.urihttp://hdl.handle.net/1885/66810
dc.description.abstractWe examine the detailed physics of the feedback mechanism by relativistic active galactic nucleus (AGN) jets interacting with a two-phase fractal interstellar medium (ISM) in the kpc-scale core of galaxies using 29 three-dimensional grid-based hydrodynamical simulations. The feedback efficiency, as measured by the amount of cloud dispersal generated by the jet-ISM interactions, is sensitive to the maximum size of clouds in the fractal cloud distribution but not to their volume filling factor. Feedback ceases to be efficient for Eddington ratios Pjet/Ledd ≲ 10-4, although systems with large cloud complexes ≳ 50 pc require jets of Eddington ratio in excess of 10-2 to disperse the clouds appreciably. Based on measurements of the bubble expansion rates in our simulations, we argue that sub-grid AGN prescriptions resulting in negative feedback in cosmological simulations without a multi-phase treatment of the ISM are good approximations if the volume filling factor of warm-phase material is less than 0.1 and the cloud complexes are smaller than 25 pc. We find that the acceleration of the dense embedded clouds is provided by the ram pressure of the high-velocity flow through the porous channels of the warm phase, flow that has fully entrained the shocked hot-phase gas it has swept up, and is additionally mass loaded by ablated cloud material. This mechanism transfers 10% to 40% of the jet energy to the cold and warm gas, accelerating it within a few 10 to 100 Myr to velocities that match those observed in a range of high- and low-redshift radio galaxies hosting powerful radio jets.
dc.publisherIOP Publishing
dc.rightsAuthor/s retain copyright
dc.sourceAstrophysical Journal, The
dc.subjectKeywords: galaxies: evolution; galaxies: formation; galaxies: jets; hydrodynamics; ISM: jets and outflows; methods: numerical
dc.titleDriving outflows with relativistic jets and the dependence of AGN feedback efficiency on interstellar medium inhomogeneity
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume757
dc.date.issued2012
local.identifier.absfor020106 - High Energy Astrophysics; Cosmic Rays
local.identifier.ariespublicationf5625xPUB1349
local.type.statusPublished Version
local.contributor.affiliationWagner, Alexander, University of Tsukuba
local.contributor.affiliationBicknell, Geoffrey, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationUmemura, M, University of Tsukuba
local.bibliographicCitation.issue2
local.identifier.doi10.1088/0004-637X/757/2/136
dc.date.updated2016-02-24T08:45:21Z
local.identifier.scopusID2-s2.0-84866401423
local.identifier.thomsonID000309108500029
dcterms.accessRightsOpen Access
CollectionsANU Research Publications

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