Publication date: May 2019
Abstract:
The Schwarzschild star is an ultracompact object beyond the Buchdahl
limit, which has Schwarzschild geometry outside its surface and positive
pressure in the external layer which vanishes at the surface. Recently
it has been shown that the Schwarzschild star is stable against
spherically-symmetric perturbations. Here we study arbitrary axial non-
spherical perturbations, and show that the observable quasinormal modes
can be as close to the Schwarzschild limit as one wishes, what makes the
Schwarzschild star a very good mimicker of a black hole. The decaying
time-domain profiles prove that the Schwarzschild star is stable against
non-spherical perturbations as well. Another peculiar feature is the
absence of echoes at the end of the ringdown. Instead we observe a non-
oscillating mode which might belong to the class of algebraically
special modes. At asymptotically late times, Schwarzschildian power-law
tails dominate in the signal.
Authors:
Konoplya, R. A.; Posada, C.; Stuchlík, Z.; Zhidenko, A.;