Formation of Black Hole–White Dwarf X-Ray Binaries in Globular Clusters
4 affiliations
- 1California Institute of Technology
- 2University of California, San Diego
- 3Allegheny College
- 4International Centre for Radio Astronomy Research—Curtin University
Abstract
Globular clusters are host to significant populations of dynamically active stellar remnants that connect to a variety of astrophysical sources. Using simulations performed with the Cluster Monte Carlo dynamics code, we study the formation of ultracompact binaries in which a stellar-mass black hole accretes material from a white dwarf companion in an orbit of less than an hour. These binary systems are prime multimessenger targets, as they can be observed both as luminous X-ray sources and as millihertz gravitational-wave sources detectable by the Laser Interferometer Space Antenna (LISA). We find that black hole+giant collisions are the primary mechanism through which such systems form. We model the outcomes of these “common envelope”-like events using the smoothed particle hydrodynamics code StarSmasher , and verify that these collisions yield black hole+white dwarf binaries that enter Roche contact on timescales ≲1 Gyr via gravitational-wave inspiral. We construct a mock catalog of local ultracompact X-ray sources and compare to candidate sources observed in globular clusters in the Milky Way (e.g., 47 Tuc X9) and external galaxies (e.g., RZ 2109 in NGC 4472). Finally, we compute the gravitational-wave strain for these sources, and show that of order one source may be resolvable in the Milky Way by LISA, representing a potentially powerful tool for observing new black holes in globular clusters.
Related
- The Ejection and Detectability of High- and Hypervelocity Stars by Compact Object Binaries in Globular Clusters
- Evolution of Stellar Activity and Habitable Zone. IV. Calcium II Infrared Triplet Activity from Open Clusters and White Dwarf Binaries
- Probing Globular Clusters using Gravitational Waves from Inspiraling Stellar-mass Binary Black Holes in Space-based Detector
- Little Red Dots as Globular Clusters in Formation
- Fast Dynamical Modelling of Milky Way Globular Clusters -- II. Impacts of Black Hole Prescriptions
BibTeX
@article{yang2026formation,
title = {{Formation of Black Hole–White Dwarf X-Ray Binaries in Globular Clusters}},
author = {William Y. W. Yang and Kyle Kremer and James C. Lombardi and Kristen C. Dage},
journal = {The Astrophysical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-4357/aeacd1},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeacd1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Formation of Black Hole–White Dwarf X-Ray Binaries in Globular Clusters
AU - William Y. W. Yang
AU - Kyle Kremer
AU - James C. Lombardi
AU - Kristen C. Dage
PY - 2026
DA - 2026/11/03
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aeacd1
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aeacd1
AB - Globular clusters are host to significant populations of dynamically active stellar remnants that connect to a variety of astrophysical sources. Using simulations performed with the Cluster Monte Carlo dynamics code, we study the formation of ultracompact binaries in which a stellar-mass black hole accretes material from a white dwarf companion in an orbit of less than an hour. These binary systems are prime multimessenger targets, as they can be observed both as luminous X-ray sources and as millihertz gravitational-wave sources detectable by the Laser Interferometer Space Antenna (LISA). We find that black hole+giant collisions are the primary mechanism through which such systems form. We model the outcomes of these “common envelope”-like events using the smoothed particle hydrodynamics code StarSmasher , and verify that these collisions yield black hole+white dwarf binaries that enter Roche contact on timescales ≲1 Gyr via gravitational-wave inspiral. We construct a mock catalog of local ultracompact X-ray sources and compare to candidate sources observed in globular clusters in the Milky Way (e.g., 47 Tuc X9) and external galaxies (e.g., RZ 2109 in NGC 4472). Finally, we compute the gravitational-wave strain for these sources, and show that of order one source may be resolvable in the Milky Way by LISA, representing a potentially powerful tool for observing new black holes in globular clusters.
SN - 1538-4357
SN - 0004-637X
ER -