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Astron. Astrophys. 333, 379-384 (1998)

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Tidal disruption Eddington envelopes around massive black holes

Andrew Ulmer 1, Bohdan Paczyski 2 and Jeremy Goodman 2

1 Max-Plank-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85740 Garching, Germany
2 Princeton University Observatory, Peyton Hall, Princeton, NJ 08544, USA

Received 20 November 1997 / Accepted 15 January 1998

Abstract

Optically-thick envelopes may form following the tidal disruption of a star by a massive black hole. Such envelopes would reprocess hard radiation from accretion close to the black hole into the UV and optical bands producing AGN-luminosity flares with duration [FORMULA]  year. We show that due to relativistic effects, the envelopes are convective. If convection is efficient, then the structure of the envelopes is similar to that described in previous work; however, the photospheric radius is shown to be very sensitive to the luminosity at the envelope base, suggesting that either the envelope collapses or the envelope expands to a maximum radius at which point a wind may set in. For an envelope without winds, we find a maximum photospheric radius of [FORMULA]  cm (i.e. minimum effective temperature [FORMULA]  K). The evolution of the envelopes is described based on simple energy arguments.

Key words: black hole physics – galaxies: active – galaxies: nuclei – quasars: general – ultraviolet: galaxies

Send offprint requests to: A. Ulmer

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© European Southern Observatory (ESO) 1998

Online publication: April 15, 1998
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