LISA Sources in Milky Way Globular Clusters

Area of Science:

• Astrophysics
• Binary Systems
• Gravitational Wave Astronomy

Background:

• Globular clusters (GCs) are dense stellar systems offering unique environments for compact object binary formation.
• The Laser Interferometer Space Antenna (LISA) is a future space-based gravitational wave observatory designed to detect low-frequency signals.

Purpose of the Study:

• To investigate the population of double compact object binaries within Milky Way globular clusters.
• To estimate the number of such binaries detectable by LISA.
• To characterize the types and potential detectability of these binaries.

Main Methods:

• Utilized 137 fully evolved globular cluster models that accurately represent Milky Way globular cluster properties.
• Simulated binary evolution within these models to identify double compact object systems.
• Estimated the detectability of these binaries by LISA based on their properties and LISA's sensitivity.

Main Results:

• An estimated ~21 double compact object binaries in Milky Way globular clusters are expected to be detectable by LISA.
• These detectable binaries include all combinations of black hole (BH), neutron star, and white dwarf components.
• Approximately 7 of these sources are predicted to be black hole-black hole binaries.
• Some black hole-black hole binaries exhibit signal-to-noise ratios sufficient for detection at extragalactic distances (Andromeda, Virgo cluster).

Conclusions:

• Milky Way globular clusters are promising sites for LISA-detectable double compact object binaries.
• The predicted population includes diverse binary types, with a significant fraction of black hole-black hole systems.
• These findings highlight the potential of LISA to probe compact object populations in dense stellar environments and even beyond our galaxy.