Dynamical friction in dark matter spikes: Corrections to Chandrasekhar’s formula

Dosopoulou, Fani 2024. Dynamical friction in dark matter spikes: Corrections to Chandrasekhar’s formula. Physical Review D (particles, fields, gravitation, and cosmology) 110 (8) , 083027. 10.1103/physrevd.110.083027

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Abstract

We consider the intermediate mass-ratio inspiral of a stellar-mass compact object with an intermediate-mass black hole that is surrounded by a dark matter density spike. The interaction of the inspiraling black hole with the dark matter particles in the spike leads to dynamical friction. This can alter the dynamics of the black hole binary, leaving an imprint on the gravitational wave signal. Previous calculations did not include in the evaluation of the dynamical friction coefficient the contribution from particles that move faster than the inspiraling black hole. This term is neglected in the standard Chandrasekhar treatment where only slower moving particles contribute to the decelerating drag. Here, we demonstrate that dynamical friction produced by the fast moving particles can have a significant effect on the evolution of a massive binary within a dark matter spike. For a density profile ρ∝r−γ with γ≲1, the dephasing of the gravitational waveform can be several orders of magnitude larger than estimated using the standard treatment. As γ approaches 0.5 the error becomes arbitrarily large. Finally, we show that dynamical friction tends to make the orbit more eccentric for any γ<1.8. However, energy loss by gravitational wave radiation is expected to dominate the inspiral, leading to orbital circularization in most cases. Published by the American Physical Society 2024

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Physics and Astronomy
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2024-10-15
Publisher:	American Physical Society
ISSN:	2470-0010
Date of First Compliant Deposit:	5 November 2024
Date of Acceptance:	13 September 2024
Last Modified:	09 Dec 2024 16:51
URI:	https://orca.cardiff.ac.uk/id/eprint/173655

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