THE HYDRODYNAMIC EFFECTS OF NUCLEAR ACTIVE GALAXY WINDS ON HOST GALAXIES.

Persistent Link:
http://hdl.handle.net/10150/187865
Title:
THE HYDRODYNAMIC EFFECTS OF NUCLEAR ACTIVE GALAXY WINDS ON HOST GALAXIES.
Author:
SCHIANO, ALLEN VINCENT ROGERS.
Issue Date:
1984
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In order to test the hypothesized existence of a powerful, thermal wind in active galactic nuclei, the hydrodynamic effects of such a wind on a model galactic interstellar medium (ISM) are investigated. The properties of several model ISMs are derived from observations of the Milky Way's ISM and those of nearby spiral and elliptical galaxies. The wind is assumed to be highly supersonic with spherical symmetry and constant mechanical luminosity, L(W). The propagation of the wind into the low density gas component of the ISM is studied using the Kompaneets approximation of a strong explosion in an exponential atmosphere. Flattened gas distributions are shown to experience "blow-out" of wind gas along the symmetry axis. The results show that for typical ISM gas pressures ( < 10⁻¹¹ ergs cm⁻³), the extent of the wind can range from 1 to 10 kpc for wind luminosities of 10⁴² to 10⁴⁶ ergs sec⁻¹ in a timescale of less than 10⁷ years. The steady state wind flow pattern and an estimate of the timescale required to reach a quasi-steady state are also determined. Next, the interaction of dense, interstellar clouds with the wind is investigated. The stability and mass loss of clouds in the wind are studied and it is proposed that clouds survive the encounter with the wind over large timescales ( >10⁷ yrs.). The physical structure and motion of the clouds are calculated, showing that large clouds (10³ solar masses) can be accelerated to velocities in excess of the galactic escape velocity. Finally, it is proposed that the Narrow Emission Line Regions (NELR) of active galaxies are the result of the interaction of active nuclei photons and a thermal wind on large, interstellar clouds. The physical state of the NELR is re-examined and shown to be compatible with this hypothesis. Arguments are presented to show that the NELR clouds must be massive and unable to be accelerated to NELR velocities by photon momentum alone. A Monte Carlo-type calculation is made to determine Narrow Emission Line profiles from an ensemble of photoionized interstellar clouds in the wind. These theoretical line profiles are shown to agree reasonably well with observed line profiles.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Astrophysics.; Space environment.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Astronomy; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Weymann, Ray

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleTHE HYDRODYNAMIC EFFECTS OF NUCLEAR ACTIVE GALAXY WINDS ON HOST GALAXIES.en_US
dc.creatorSCHIANO, ALLEN VINCENT ROGERS.en_US
dc.contributor.authorSCHIANO, ALLEN VINCENT ROGERS.en_US
dc.date.issued1984en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn order to test the hypothesized existence of a powerful, thermal wind in active galactic nuclei, the hydrodynamic effects of such a wind on a model galactic interstellar medium (ISM) are investigated. The properties of several model ISMs are derived from observations of the Milky Way's ISM and those of nearby spiral and elliptical galaxies. The wind is assumed to be highly supersonic with spherical symmetry and constant mechanical luminosity, L(W). The propagation of the wind into the low density gas component of the ISM is studied using the Kompaneets approximation of a strong explosion in an exponential atmosphere. Flattened gas distributions are shown to experience "blow-out" of wind gas along the symmetry axis. The results show that for typical ISM gas pressures ( < 10⁻¹¹ ergs cm⁻³), the extent of the wind can range from 1 to 10 kpc for wind luminosities of 10⁴² to 10⁴⁶ ergs sec⁻¹ in a timescale of less than 10⁷ years. The steady state wind flow pattern and an estimate of the timescale required to reach a quasi-steady state are also determined. Next, the interaction of dense, interstellar clouds with the wind is investigated. The stability and mass loss of clouds in the wind are studied and it is proposed that clouds survive the encounter with the wind over large timescales ( >10⁷ yrs.). The physical structure and motion of the clouds are calculated, showing that large clouds (10³ solar masses) can be accelerated to velocities in excess of the galactic escape velocity. Finally, it is proposed that the Narrow Emission Line Regions (NELR) of active galaxies are the result of the interaction of active nuclei photons and a thermal wind on large, interstellar clouds. The physical state of the NELR is re-examined and shown to be compatible with this hypothesis. Arguments are presented to show that the NELR clouds must be massive and unable to be accelerated to NELR velocities by photon momentum alone. A Monte Carlo-type calculation is made to determine Narrow Emission Line profiles from an ensemble of photoionized interstellar clouds in the wind. These theoretical line profiles are shown to agree reasonably well with observed line profiles.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectAstrophysics.en_US
dc.subjectSpace environment.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAstronomyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWeymann, Rayen_US
dc.identifier.proquest8504758en_US
dc.identifier.oclc693569174en_US
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