Publication date: Jan 2019
Abstract:
It is well known that a hypothetical compact object that looks like an
Einsteinian (Schwarzschild or Kerr) black hole everywhere except a small
region near its surface should have the ringdown profile predicted by
the Einstein theory at early and intermediate times, but modified by the
so-called echoes at late times. A similar phenomenon appears when one
considers an Einsteinian black hole and a shell of matter placed at some
distance from it, so that astrophysical estimates could be made for the
allowed mass of the black hole environment. While echoes for both
systems have been extensively studied recently, no such analysis has
been done for a system featuring phenomena simultaneously, that is,
echoes due to new physics near the surface/event horizon and echoes due
to matter at some distance from the black hole. Here, following Damour
and Solodukhin [Phys. Rev. D 76, 024016 (2007),
10.1103/PhysRevD.76.024016] and Cardoso et al. [Phys. Rev. Lett. 116,
171101 (2016), 10.1103/PhysRevLett.116.171101], we consider a
traversable wormhole obtained by identifying two Schwarzschild metrics
with the same mass M at the throat, which is near the Schwarzschild
radius, and add a nonthin shell of matter at a distance. This allows us
to understand how the echoes of the surface of the compact object are
affected by the astrophysical environment at a distance. The
straightforward calculations for the time-domain profiles of such a
system support the expectations that if the echoes are observed, they
should most probably be ascribed to some new physics near the event
horizon rather than some „environmental“ effect.
Authors:
Konoplya, R. A.; Stuchlík, Z.; Zhidenko, A.;