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Super-Eddington accretion in tidal disruption events: the impact of realistic fallback rates on accretion rates

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journal contribution
posted on 01.02.2019, 09:50 by Samantha Wu, Eric R. Coughlin, Chris Nixon
After the tidal disruption of a star by a massive black hole, disrupted stellar debris can fall back to the hole at a rate significantly exceeding its Eddington limit. To understand how black hole mass affects the duration of super-Eddington accretion in tidal disruption events, we first run a suite of simulations of the disruption of a Solar-like star by a supermassive black hole of varying mass to directly measure the fallback rate on to the hole, and we compare these fallback rates to the analytic predictions of the ‘frozen-in’ model. Then, adopting a zero-Bernoulli accretion flow as an analytic prescription for the accretion flow around the hole, we investigate how the accretion rate on to the black hole evolves with the more accurate fallback rates calculated from the simulations. We find that numerically simulated fallback rates yield accretion rates on to the hole that can, depending on the black hole mass, be nearly an order of magnitude larger than those predicted by the frozen-in approximation. Our results place new limits on the maximum black hole mass for which super-Eddington accretion occurs in tidal disruption events.

Funding

ERC acknowledges support from NASA through the Einstein Fellowship Program, grant PF6-170150. CN is supported by the Science and Technology Facilities Council (grant number ST/M005917/1). The Theoretical Astrophysics Group at the University of Leicester is supported by an STFC Consolidated Grant. This research used the Savio computational cluster resource provided by the Berkeley Research Computing program at the University of California, Berkeley (supported by the UC Berkeley Chancellor, Vice Chancellor for Research, and Chief Information Officer).

History

Citation

Monthly Notices of the Royal Astronomical Society, 2018, 478 (3), pp. 3016-3024 (9)

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press (OUP), Royal Astronomical Society

issn

0035-8711

eissn

1365-2966

Acceptance date

15/04/2018

Copyright date

2018

Available date

01/02/2019

Publisher version

https://academic.oup.com/mnras/article/478/3/3016/4978468

Language

en