A 2-2-hole is an explicit realization of a horizonless object that can still very closely resemble a black hole. An ordinary relativistic gas can serve as the matter source for a 2-2-hole solution of quadratic gravity, and this leads to a calculable area-law entropy. Here we show that it also leads to an estimate of the damping of a gravitational wave as it travels to the center of the 2-2-hole and back out again. We identify two frequency dependent effects that greatly diminish the damping. Spinning 2-2-hole solutions are not known, but we are still able to consider some spin dependent effects. The frequency and spin dependence of the damping helps to determine the possible echo resonance signal from the spinning remnants of merger events. It also controls the fate of the ergoregion instability.

中文翻译：

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2-2 孔中的引力波阻尼

2-2 孔是一个无视界物体的明确实现，它仍然可以非常类似于黑洞。普通的相对论气体可以作为二次引力的 2-2 孔解的物质源，这导致可计算的面积定律熵。在这里，我们表明，当引力波传播到 2-2 孔的中心并再次返回时，它也导致了对引力波阻尼的估计。我们确定了两种频率相关的效应，它们极大地减少了阻尼。自旋 2-2 孔解是未知的，但我们仍然能够考虑一些自旋相关效应。阻尼的频率和自旋相关性有助于从合并事件的自旋残余物中确定可能的回声共振信号。它还控制着麦角区域不稳定性的命运。