We determine the causal structure of the McVittie spacetime for a cosmological model with an asymmetric bounce. The analysis includes the computation of trapping horizons; regular, trapped, and antitrapped regions; and the integration of the trajectories of radial null geodesics before, during, and after the bounce. We find a trapped region since the beginning of the contracting phase up to shortly before the bounce, thus showing the existence of a black hole. When the universe reaches a certain minimum scale in the contracting phase, the trapping horizons disappear, and the central singularity becomes naked. These results suggest that neither a contracting nor an expanding universe can accommodate a black hole at all times.

中文翻译：

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不对称宇宙反弹中的黑洞

我们确定具有不对称弹跳的宇宙学模型的McVittie时空的因果结构。分析包括圈定视野的计算；规则，陷阱和反陷阱区域；以及反弹之前，之中和之后的径向零大地测量线的轨迹的积分。从收缩阶段开始直到反弹之前不久，我们发现了一个陷井区域，因此表明存在黑洞。当宇宙在收缩阶段达到一定的最小尺度时，陷井消失了，中央的奇点变得裸露。这些结果表明，收缩的宇宙和膨胀的宇宙都无法始终容纳黑洞。