Cufari, M, Nixon, CJ and Coughlin, ER (2023) Tidal capture of stars by supermassive black holes: implications for periodic nuclear transients and quasi-periodic eruptions. Monthly Notices of the Royal Astronomical Society: Letters, 520 (1). L38-L41. ISSN 1745-3925
Abstract
Stars that plunge into the centre of a galaxy are tidally perturbed by a supermassive black hole (SMBH), with closer encounters resulting in larger perturbations. Exciting these tides comes at the expense of the star’s orbital energy, which leads to the naive conclusion that a smaller pericentre (i.e. a closer encounter between the star and SMBH) always yields a more tightly bound star to the SMBH. However, once the pericentre distance is small enough that the star is partially disrupted, morphological asymmetries in the mass lost by the star can yield an increase in the orbital energy of the surviving core, resulting in its ejection – not capture – by the SMBH. Using smoothed particle hydrodynamics simulations, we show that the combination of these two effects – tidal excitation and asymmetric mass-loss – results in a maximum amount of energy lost through tides of ∼2.5 per cent
of the binding energy of the star, which is significantly smaller than the theoretical maximum of the total stellar binding energy. This result implies that stars that are repeatedly partially disrupted by SMBHs many (≳10) times on short-period orbits (≲few years), as has been invoked to explain the periodic nuclear transient ASASSN-14ko and quasi-periodic eruptions, must be bound to the SMBH through a mechanism other than tidal capture, such as a dynamical exchange (i.e. Hills capture).
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Author(s). This is an author produced version of an article published in Monthly Notices of the Royal Astronomical Society: Letters. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | hydrodynamics, galaxies: nuclei |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 07 Feb 2023 10:55 |
Last Modified: | 08 Feb 2023 12:32 |
Published Version: | http://dx.doi.org/10.1093/mnrasl/slad001 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnrasl/slad001 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:196147 |