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Abstract:
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Black hole's response to external perturbations will carry significant
information about these exotic objects. Its response, shortly
after the initial `kick', is known to be ruled by the damped oscillation
of the perturbating eld, called quasinormal modes(QNMs), followed
by the tails of decay and is the characteristic of the background black
hole spacetime.
In the last three decades, several shortcomings came out in the
Einstein's General Theory of Relativity(GTR). Such issues come, especially,
from observational cosmology and quantum eld theory. In
the rst case, for example, the observed accelerated expansion of the
universe and the hypothesized mysterious dark energy still lack a satisfactory
explanation. Secondly, GTR is a classical theory which does
not work as a fundamental theory, when one wants to achieve a full
quantum description of gravity. Due to these facts modi cation to
GTR or alternative theories for gravity have been considered. Two
potential approaches towards these problems are the quintessence
model for dark energy and Ho rava-Lifshitz(HL) gravity. Quintessence
is a dynamical model of dark energy which is often realized by scalar
eld mechanism. HL gravity is the recently proposed theory of gravity,
which is renormalizable in power counting arguments. The two
models are considered as a potential candidate in explaining these
issues. |