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White Dwarf Subsystems in Core-Collapsed Globular Clusters

Kremer, Kyle and Rui, Nicholas Z. and Weatherford, Newlin C. and Chatterjee, Sourav and Fragione, Giacomo and Rasio, Frederic A. and Rodriguez, Carl L. and Ye, Claire S. (2021) White Dwarf Subsystems in Core-Collapsed Globular Clusters. Astrophysical Journal, 917 (1). Art. No. 28. ISSN 0004-637X. doi:10.3847/1538-4357/ac06d4.

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Numerical and observational evidence suggests that massive white dwarfs dominate the innermost regions of core-collapsed globular clusters by both number and total mass. Using NGC 6397 as a test case, we constrain the features of white dwarf populations in core-collapsed clusters, both at present day and throughout their lifetimes. The dynamics of these white dwarf subsystems have a number of astrophysical implications. We demonstrate that the collapse of globular cluster cores is ultimately halted by the dynamical burning of white dwarf binaries. We predict that core-collapsed clusters in the local universe yield a white dwarf merger rate of O(10) Gpc⁻³ yr⁻¹, roughly 0.1%–1% of the observed Type Ia supernova rate. We show that prior to merger, inspiraling white dwarf binaries will be observable as gravitational-wave sources at millihertz and decihertz frequencies. Over 90% of these mergers have a total mass greater than the Chandrasekhar limit. We argue that the merger/collision remnants, if not destroyed completely in an explosive transient, may be observed in core-collapsed clusters either as young neutron stars/pulsars/magnetars (in the event of accretion-induced collapse) or as young massive white dwarfs offset from the standard white dwarf cooling sequence. Finally, we show that collisions between white dwarfs and main-sequence stars, which may be detectable as bright transients, occur at a rate of O(100) Gpc⁻³ yr⁻¹ in the local universe. We find that these collisions lead to depletion of blue straggler stars and main-sequence star binaries in the centers of core-collapsed clusters.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kremer, Kyle0000-0002-4086-3180
Rui, Nicholas Z.0000-0002-1884-3992
Weatherford, Newlin C.0000-0002-9660-9085
Chatterjee, Sourav0000-0002-3680-2684
Fragione, Giacomo0000-0002-7330-027X
Rasio, Frederic A.0000-0002-7132-418X
Rodriguez, Carl L.0000-0003-4175-8881
Ye, Claire S.0000-0001-9582-881X
Additional Information:© 2021. The American Astronomical Society. Received 2021 April 23; revised 2021 May 20; accepted 2021 May 29; published 2021 August 11. K.K. thanks Ilaria Caiazzo, Kevin Burdge, Jim Fuller, and Tony Piro for helpful discussions. We also thank the anonymous referee for helpful suggestions and careful review of the manuscript. K.K. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2001751. N.Z.R. acknowledges support from the Dominic Orr Graduate Fellowship. N.C.W. acknowledges support from the CIERA Riedel Family Graduate Fellowship. S.C. acknowledges support of the Department of Atomic Energy, Government of India, under project no. 12-R&D-TFR-5.02-0200. F.A.R. and C.S.Y. acknowledge support from NSF grant AST-1716762 at Northwestern University.
Funding AgencyGrant Number
NSF Astronomy and Astrophysics FellowshipAST-2001751
Dominic Orr Graduate FellowshipUNSPECIFIED
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Department of Atomic Energy (India)12-R&D-TFR-5.02-0200
Subject Keywords:White dwarf stars; Globular star clusters; Type Ia supernovae; Stellar dynamics; Gravitational wave astronomy
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: White dwarf stars (1799); Globular star clusters (656); Type Ia supernovae (1728); Stellar dynamics (1596); Gravitational wave astronomy (675)
Record Number:CaltechAUTHORS:20210813-181203790
Persistent URL:
Official Citation:Kyle Kremer et al 2021 ApJ 917 28
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110262
Deposited By: George Porter
Deposited On:13 Aug 2021 22:35
Last Modified:13 Aug 2021 22:35

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