dc.contributor.author | Krause, Martin | |
dc.contributor.author | Schartmann, M. | |
dc.contributor.author | Burkert, A. | |
dc.date.accessioned | 2017-04-25T16:22:23Z | |
dc.date.available | 2017-04-25T16:22:23Z | |
dc.date.issued | 2012-10-01 | |
dc.identifier.citation | Krause , M , Schartmann , M & Burkert , A 2012 , ' Magnetohydrodynamic stability of broad line region clouds ' , Monthly Notices of the Royal Astronomical Society , vol. 425 , pp. 3172-3187 . https://doi.org/10.1111/j.1365-2966.2012.21642.x | |
dc.identifier.issn | 0035-8711 | |
dc.identifier.other | Bibtex: urn:7a107a041e2a8d906ee68fb64dc72fb8 | |
dc.identifier.other | ORCID: /0000-0002-9610-5629/work/63687389 | |
dc.identifier.uri | http://hdl.handle.net/2299/18080 | |
dc.description | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2012 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. The version of record is available at doi: 10.1111/j.1365-2966.2012.21642.x. | |
dc.description.abstract | Hydrodynamic stability has been a longstanding issue for the cloud model of the broad line region in active galactic nuclei. We argue that the clouds may be gravitationally bound to the supermassive black hole. If true, stabilization by thermal pressure alone becomes even more difficult. We further argue that if magnetic fields are present in such clouds at a level that could affect the stability properties, they need to be strong enough to compete with the radiation pressure on the cloud. This would imply magnetic field values of a few gauss for a sample of active galactic nuclei we draw from the literature. We then investigate the effect of several magnetic configurations on cloud stability in axisymmetric magnetohydrodynamic simulations. For a purely azimuthal magnetic field which provides the dominant pressure support, the cloud first gets compressed by the opposing radiative and gravitational forces. The pressure inside the cloud then increases, and it expands vertically. Kelvin-Helmholtz and column density instabilities lead to a filamentary fragmentation of the cloud. This radiative dispersion continues until the cloud is shredded down to the resolution level. For a helical magnetic field configuration, a much more stable cloud core survives with a stationary density histogram which takes the form of a power law. Our simulated clouds develop sub-Alfvénic internal motions on the level of a few hundred km s-1. | en |
dc.format.extent | 16 | |
dc.format.extent | 6519481 | |
dc.language.iso | eng | |
dc.relation.ispartof | Monthly Notices of the Royal Astronomical Society | |
dc.subject | hydrodynamics, radiative transfer, ISM: structure, galaxies: active, galaxies: nuclei | |
dc.title | Magnetohydrodynamic stability of broad line region clouds | en |
dc.contributor.institution | Centre for Astrophysics Research (CAR) | |
dc.contributor.institution | School of Physics, Engineering & Computer Science | |
dc.contributor.institution | Department of Physics, Astronomy and Mathematics | |
dc.description.status | Peer reviewed | |
rioxxterms.versionofrecord | 10.1111/j.1365-2966.2012.21642.x | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true | |