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Hydrodynamics of Collisions and Close Encounters between Stellar Black Holes and Main-sequence Stars

Kremer, Kyle and Lombardi, James C., Jr. and Lu, Wenbin and Piro, Anthony L. and Rasio, Frederic A. (2022) Hydrodynamics of Collisions and Close Encounters between Stellar Black Holes and Main-sequence Stars. Astrophysical Journal, 933 (2). Art. No. 203. ISSN 0004-637X. doi:10.3847/1538-4357/ac714f.

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Recent analyses have shown that close encounters between stars and stellar black holes occur frequently in dense star clusters. Depending upon the distance at closest approach, these interactions can lead to dissipating encounters such as tidal captures and disruptions, or direct physical collisions, all of which may be accompanied by bright electromagnetic transients. In this study, we perform a wide range of hydrodynamic simulations of close encounters between black holes and main-sequence stars that collectively cover the parameter space of interest, and we identify and classify the various possible outcomes. In the case of nearly head-on collisions, the star is completely disrupted with roughly half of the stellar material becoming bound to the black hole. For more distant encounters near the classical tidal-disruption radius, the star is only partially disrupted on the first pericenter passage. Depending upon the interaction details, the partially disrupted stellar remnant may be tidally captured by the black hole or become unbound (in some cases, receiving a sufficiently large impulsive kick from asymmetric mass loss to be ejected from its host cluster). In the former case, the star will undergo additional pericenter passages before ultimately being disrupted fully. Based on the properties of the material bound to the black hole at the end of our simulations (in particular, the total bound mass and angular momentum), we comment upon the expected accretion process and associated electromagnetic signatures that are likely to result.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kremer, Kyle0000-0002-4086-3180
Lombardi, James C., Jr.0000-0002-7444-7599
Lu, Wenbin0000-0002-1568-7461
Piro, Anthony L.0000-0001-6806-0673
Rasio, Frederic A.0000-0002-7132-418X
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 January 28; revised 2022 May 15; accepted 2022 May 17; published 2022 July 14. We thank the anonymous referee for a careful review of the manuscript and many helpful comments. We thank Josh Fixelle for contributions in the early stages of this project. We also thank Byron Rich for helping to prepare workstations, purchased with a grant from the George I. Alden Trust, to run several of the simulations of this paper. K.K. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2001751. W.L. is supported by the Lyman Spitzer, Jr. Fellowship at Princeton University. This work was supported by NSF Grant AST-2108624 and NASA ATP Grant 80NSSC22K0722 at Northwestern University. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology.
Funding AgencyGrant Number
George I. Alden TrustUNSPECIFIED
NSF Astronomy and Astrophysics FellowshipAST-2001751
Princeton UniversityUNSPECIFIED
Northwestern UniversityUNSPECIFIED
Subject Keywords:Astrophysical black holes; Hydrodynamical simulations; Tidal disruption; Globular star clusters; Transient sources
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Astrophysical black holes (98); Hydrodynamical simulations (767); Tidal disruption (1696); Globular star clusters (656); Transient sources (1851)
Record Number:CaltechAUTHORS:20220517-214238256
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Official Citation:Kyle Kremer et al 2022 ApJ 933 203
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114781
Deposited By: George Porter
Deposited On:18 May 2022 14:15
Last Modified:03 Aug 2022 17:25

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