Accretion onto a moving black hole for stiff equations of state
Abstract
We revisit accretion of an asymptotically uniform fluid onto a moving Schwarzschild black hole, the relativistic analog of Bondi-Hoyle-Lyttleton accretion. Expanding on previous treatments, we focus on relativistic accretion of stiff fluids with adiabatic indices Γ≥ 5/3, which is particularly relevant for the treatment of primordial black holes captured by neutron stars. We perform numerical simulations to systematically explore the dependence of the steady-state accretion and drag rates on the asymptotic sound speed a∞ and relative speed v∞, and identify different regimes, both subsonic and supersonic, in which these rates either increase or decrease with respect to the spherical accretion rate for v∞ = 0. We propose simple analytical approximations that capture the qualitative features observed in the dependence of the accretion and drag rates on a∞ and v∞.
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BibTeX
@misc{ewell2026accretion,
title = {{Accretion onto a moving black hole for stiff equations of state}},
author = {Elliott Ewell and Peter K. Harris and Thomas W. Baumgarte and Stuart L. Shapiro},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.12058},
eprint = {2609.12058},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.12058},
}
RIS
TY - UNPB
TI - Accretion onto a moving black hole for stiff equations of state
AU - Elliott Ewell
AU - Peter K. Harris
AU - Thomas W. Baumgarte
AU - Stuart L. Shapiro
PY - 2026
DA - 2026/09/10
PB - arXiv
DO - 10.48550/arxiv.2609.12058
UR - https://arxiv.org/abs/2609.12058
AB - We revisit accretion of an asymptotically uniform fluid onto a moving Schwarzschild black hole, the relativistic analog of Bondi-Hoyle-Lyttleton accretion. Expanding on previous treatments, we focus on relativistic accretion of stiff fluids with adiabatic indices Γ≥ 5/3, which is particularly relevant for the treatment of primordial black holes captured by neutron stars. We perform numerical simulations to systematically explore the dependence of the steady-state accretion and drag rates on the asymptotic sound speed a_∞ and relative speed v_∞, and identify different regimes, both subsonic and supersonic, in which these rates either increase or decrease with respect to the spherical accretion rate for v_∞ = 0. We propose simple analytical approximations that capture the qualitative features observed in the dependence of the accretion and drag rates on a_∞ and v_∞.
ER -