We consider black holes which form from an initially spherically symmetric super-Hubble perturbation of a cosmological background filled by a perfect fluid p = w ρ with w ∈ (0,1]. Previous work has shown that when w = 1/3 (radiation), there is a critical threshold for black hole formation (δ_c), which, to a very good approximation, only depends upon the curvature of the compaction function around its peak value. We find that this generalizes to all w ≳ 1/3; for smaller ws the knowledge of the full shape of the compaction function is necessary. We provide analytic approximations for δ_c which are accurate for w ∈ [1/3,1].

我们考虑黑洞，这些黑洞是由充满完美流体的宇宙背景的最初球对称超级哈勃扰动形成的 p  = 瓦特 ρ 和 w  ＆in; （0,1]。先前的工作表明w  = 1/3 （辐射），黑洞形成有一个临界阈值（δ _ç，这是一个非常好的近似值，仅取决于压实函数在其峰值附近的曲率。我们发现这可以推广到所有人w  ＆gtrsim; 1/3; 对于较小的w必须了解压实功能的完整形状。我们为提供解析近似δ _ç 哪些是准确的 w  ＆in; [1 / 3,1]。