Relativistic Bondi accretion for stiff equations of state
Relativistic Bondi accretion for stiff equations of state
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刚性状态方程的相对论 Bondi 吸积
DOI：
10.1093/mnras/stab161
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发表时间：
2021
影响因子：
4.8
通讯作者：
Shapiro, Stuart L
中科院分区：
文献类型：
--
作者：
Richards, Chloe B;Baumgarte, Thomas W;Shapiro, Stuart L
对于具有绝热指数Γ>；5/3的刚性多变状态方程，我们重新讨论了Bondi吸积--定态的、绝热的、球状气体在渐近均匀介质中静止的Schwarzschild黑洞上的流动。需要用广义相对论处理来确定它们的吸积率，我们给出了它的精确表达式。我们讨论了软的和硬的EOS结果之间的几个定性差异--包括Γ≥5/3的EOS的最小稳态吸积率的出现--并探索了极限情况以检验这些差异。作为一个例子，我们重点介绍了Γ=2的结果，它经常被用于数值模拟中子星的状态方程。我们还讨论了这个指数的一个特例--极端相对论的“因果”状态方程，P=ρ。对于核密度以上仍未确定的中子星状态方程，后者是一个有用的极限。例如，这些结果对估计位于中子星中心的微型黑洞的吸积率是有用的。
We revisit Bondi accretion – steady-state, adiabatic, spherical gas flow on to a Schwarzschild black hole at rest in an asymptotically homogeneous medium – for stiff polytropic equations of state (EOSs) with adiabatic indices Γ > 5/3. A general relativistic treatment is required to determine their accretion rates, for which we provide exact expressions. We discuss several qualitative differences between results for soft and stiff EOSs – including the appearance of a minimum steady-state accretion rate for EOSs with Γ ≥ 5/3 – and explore limiting cases in order to examine these differences. As an example, we highlight results for Γ = 2, which is often used in numerical simulations to model the EOS of neutron stars. We also discuss a special case with this index, the ultrarelativistic ‘causal’ EOS,P= ρ. The latter serves as a useful limit for the still undetermined neutron star EOS above nuclear density. The results are useful, for example, to estimate the accretion rate on to a mini-black hole residing at the centre of a neutron star.