Echoes from Quantum Black Holes. (arXiv:1905.00446v1 [gr-qc])
<a href="http://arxiv.org/find/gr-qc/1/au:+Wang_Q/0/1/0/all/0/1">Qingwen Wang</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Oshita_N/0/1/0/all/0/1">Naritaka Oshita</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Afshordi_N/0/1/0/all/0/1">Niayesh Afshordi</a>
One of the most triumphant predictions of the theory if general relativity
was the recent LIGO-Virgo detection of gravitational wave (GW) signals produced
in binary black hole (BH) mergers. However, it is suggested that exotic compact
objects, proposed in quantum gravity models of BHs, may produce similar
classical GW waveforms, followed by delayed repeating “echoes”. In a companion
paper [1], we have presented different arguments for a universal Boltzmann
reflectivity of quantum BH horizons. Here, we investigate the resulting echoes
from this prescription. We derive corresponding quasi-normal modes (QNMs) for
quantum BHs analytically, and show how their initial conditions can be related
to the QNMs of classical BHs. Ergoregion instability is suppressed by the
imperfect reflectivity. We then compare the analytic and numerical predictions
for echoes in real time, verifying their consistency. In particular, we find
that the amplitudes of the first ~20 echoes decay inversely with time, while
the subsequent echoes decay exponentially. Finally, we present predictions for
the signal-to-noise ratio of echoes for spinning BHs, which should be
imminently detectable for massive remnants, subject to the uncertainty in the
nonlinear initial conditions of the BH merger.
One of the most triumphant predictions of the theory if general relativity
was the recent LIGO-Virgo detection of gravitational wave (GW) signals produced
in binary black hole (BH) mergers. However, it is suggested that exotic compact
objects, proposed in quantum gravity models of BHs, may produce similar
classical GW waveforms, followed by delayed repeating “echoes”. In a companion
paper [1], we have presented different arguments for a universal Boltzmann
reflectivity of quantum BH horizons. Here, we investigate the resulting echoes
from this prescription. We derive corresponding quasi-normal modes (QNMs) for
quantum BHs analytically, and show how their initial conditions can be related
to the QNMs of classical BHs. Ergoregion instability is suppressed by the
imperfect reflectivity. We then compare the analytic and numerical predictions
for echoes in real time, verifying their consistency. In particular, we find
that the amplitudes of the first ~20 echoes decay inversely with time, while
the subsequent echoes decay exponentially. Finally, we present predictions for
the signal-to-noise ratio of echoes for spinning BHs, which should be
imminently detectable for massive remnants, subject to the uncertainty in the
nonlinear initial conditions of the BH merger.
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