Two‐dimensional adiabatic flows on to a black hole – I. Fluid accretion
Identifieur interne : 000320 ( Main/Exploration ); précédent : 000319; suivant : 000321Two‐dimensional adiabatic flows on to a black hole – I. Fluid accretion
Auteurs : Roger D. Blandford [États-Unis] ; Mitchell C. Begelman [États-Unis]Source :
- Monthly Notices of the Royal Astronomical Society [ 0035-8711 ] ; 2004-03.
English descriptors
Abstract
When gas accretes on to a black hole, at a rate either much less than or much greater than the Eddington rate, it is likely to do so in an ‘adiabatic’ or radiatively inefficient manner. Under fluid (as opposed to magnetohydrodynamic) conditions, the disc should become convective and evolve toward a state of marginal instability. We model the resulting disc structure as ‘gyrentropic’, with convection proceeding along common surfaces of constant angular momentum, Bernouilli function and entropy, called ‘gyrentropes’. We present a family of two‐dimensional, self‐similar models that describes the time‐averaged disc structure. We then suppose that there is a self‐similar, Newtonian torque, which dominates the angular momentum transport and that the Prandtl number is large so that convection dominates the heat transport. The torque drives inflow and meridional circulation and the resulting flow is computed. Convective transport will become ineffectual near the disc surface. It is conjectured that this will lead to a large increase of entropy across a ‘thermal front’, which we identify as the effective disc surface and the base of an outflow. The conservation of mass, momentum and energy across this thermal front permits a matching of the disc models to self‐similar outflow solutions. We then demonstrate that self‐similar disc solutions can be matched smoothly on to relativistic flows at small radius and thin discs at large radius. This model of adiabatic accretion is contrasted with some alternative models that have been discussed recently. The disc models developed in this paper should be useful for interpreting numerical, fluid dynamical simulations. Related principles to those described here may govern the behaviour of astrophysically relevant, magnetohydrodynamic disc models.
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DOI: 10.1111/j.1365-2966.2004.07425.x
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Begelman</name></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:24434D9DDD93E41DA6143F94944BB8BEBC4B05CC</idno><date when="2004" year="2004">2004</date><idno type="doi">10.1111/j.1365-2966.2004.07425.x</idno><idno type="url">https://api.istex.fr/document/24434D9DDD93E41DA6143F94944BB8BEBC4B05CC/fulltext/pdf</idno><idno type="wicri:Area/Main/Corpus">000614</idno><idno type="wicri:Area/Main/Curation">000614</idno><idno type="wicri:Area/Main/Exploration">000320</idno><idno type="wicri:explorRef" wicri:stream="Main" wicri:step="Exploration">000320</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a" type="main" xml:lang="en">Two‐dimensional adiabatic flows on to a black hole – I. Fluid accretion</title><author><name sortKey="Blandford, Roger D" sort="Blandford, Roger D" uniqKey="Blandford R" first="Roger D." last="Blandford">Roger D. Blandford</name><affiliation wicri:level="1"><country xml:lang="fr">États-Unis</country><wicri:regionArea>KIPAC, Stanford University, PO Box 20450, MS 29, Stanford, CA 94309</wicri:regionArea><wicri:noRegion>CA 94309</wicri:noRegion></affiliation><affiliation wicri:level="1"><country xml:lang="fr" wicri:curation="lc">États-Unis</country><wicri:regionArea>E‐mail: (RDB); (MCB)†Also at: Theoretical Astrophysics, Caltech 130‐33, Pasadena, CA 91125, USA.‡Also at: Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309‐0440</wicri:regionArea><wicri:noRegion>CO 80309‐0440</wicri:noRegion></affiliation><affiliation wicri:level="1"><country wicri:rule="url">États-Unis</country></affiliation></author><author><name sortKey="Begelman, Mitchell C" sort="Begelman, Mitchell C" uniqKey="Begelman M" first="Mitchell C." last="Begelman">Mitchell C. Begelman</name><affiliation wicri:level="1"><country xml:lang="fr">États-Unis</country><wicri:regionArea>JILA, University of Colorado, Boulder, CO 80309‐0440</wicri:regionArea><wicri:noRegion>CO 80309‐0440</wicri:noRegion></affiliation><affiliation wicri:level="1"><country xml:lang="fr" wicri:curation="lc">États-Unis</country><wicri:regionArea>E‐mail: (RDB); (MCB)†Also at: Theoretical Astrophysics, Caltech 130‐33, Pasadena, CA 91125, USA.‡Also at: Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309‐0440</wicri:regionArea><wicri:noRegion>CO 80309‐0440</wicri:noRegion></affiliation><affiliation wicri:level="1"><country wicri:rule="url">États-Unis</country></affiliation></author></analytic><monogr></monogr><series><title level="j">Monthly Notices of the Royal Astronomical Society</title><idno type="ISSN">0035-8711</idno><idno type="eISSN">1365-2966</idno><imprint><publisher>Blackwell Science Ltd</publisher><pubPlace>23 Ainslie Place , Edinburgh EH3 6AJ , UK . Telephone (0131) 226 7232 Fax (0131) 226 3803</pubPlace><date type="published" when="2004-03">2004-03</date><biblScope unit="volume">349</biblScope><biblScope unit="issue">1</biblScope><biblScope unit="page" from="68">68</biblScope><biblScope unit="page" to="86">86</biblScope></imprint><idno type="ISSN">0035-8711</idno></series><idno type="istex">24434D9DDD93E41DA6143F94944BB8BEBC4B05CC</idno><idno type="DOI">10.1111/j.1365-2966.2004.07425.x</idno><idno type="ArticleID">MNR7425</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0035-8711</idno></seriesStmt></fileDesc><profileDesc><textClass><keywords scheme="KwdEn" xml:lang="en"><term>accretion, accretion discs</term><term>black hole physics</term><term>hydrodynamics</term><term>quasars: absorption lines</term></keywords></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">When gas accretes on to a black hole, at a rate either much less than or much greater than the Eddington rate, it is likely to do so in an ‘adiabatic’ or radiatively inefficient manner. Under fluid (as opposed to magnetohydrodynamic) conditions, the disc should become convective and evolve toward a state of marginal instability. We model the resulting disc structure as ‘gyrentropic’, with convection proceeding along common surfaces of constant angular momentum, Bernouilli function and entropy, called ‘gyrentropes’. We present a family of two‐dimensional, self‐similar models that describes the time‐averaged disc structure. We then suppose that there is a self‐similar, Newtonian torque, which dominates the angular momentum transport and that the Prandtl number is large so that convection dominates the heat transport. The torque drives inflow and meridional circulation and the resulting flow is computed. Convective transport will become ineffectual near the disc surface. It is conjectured that this will lead to a large increase of entropy across a ‘thermal front’, which we identify as the effective disc surface and the base of an outflow. The conservation of mass, momentum and energy across this thermal front permits a matching of the disc models to self‐similar outflow solutions. We then demonstrate that self‐similar disc solutions can be matched smoothly on to relativistic flows at small radius and thin discs at large radius. This model of adiabatic accretion is contrasted with some alternative models that have been discussed recently. The disc models developed in this paper should be useful for interpreting numerical, fluid dynamical simulations. Related principles to those described here may govern the behaviour of astrophysically relevant, magnetohydrodynamic disc models.</div></front></TEI><affiliations><list><country><li>États-Unis</li></country></list><tree><country name="États-Unis"><noRegion><name sortKey="Blandford, Roger D" sort="Blandford, Roger D" uniqKey="Blandford R" first="Roger D." last="Blandford">Roger D. Blandford</name></noRegion><name sortKey="Begelman, Mitchell C" sort="Begelman, Mitchell C" uniqKey="Begelman M" first="Mitchell C." last="Begelman">Mitchell C. Begelman</name><name sortKey="Begelman, Mitchell C" sort="Begelman, Mitchell C" uniqKey="Begelman M" first="Mitchell C." last="Begelman">Mitchell C. Begelman</name><name sortKey="Begelman, Mitchell C" sort="Begelman, Mitchell C" uniqKey="Begelman M" first="Mitchell C." last="Begelman">Mitchell C. Begelman</name><name sortKey="Blandford, Roger D" sort="Blandford, Roger D" uniqKey="Blandford R" first="Roger D." last="Blandford">Roger D. Blandford</name><name sortKey="Blandford, Roger D" sort="Blandford, Roger D" uniqKey="Blandford R" first="Roger D." last="Blandford">Roger D. Blandford</name></country></tree></affiliations></record>Pour manipuler ce document sous Unix (Dilib)
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