Publication: CLASSICAL STABILITY AND FORMATION OF BLACK HOLES BEYOND GENERAL RELATIVITY
Date
2022-01
Authors
RODRÍGUEZ BAEZ, YOLBEIKER
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Abstract
In this thesis, we will discuss the formation, classical stability, and an observational signature of black holes in the presence of additional degrees of freedom.
Adding additional degrees of freedom though extra fundamental fields in the action seems to be the most promising way to construct theories of gravity beyond
general relativity.
Firstly, we present a numerical study of the gravitational collapse of k-essence
model, in which a scalar field with a non-canonical kinetic term is added into the
action. We will show that the scalar field propagates in the so-called emergent
spacetime described by a metric different from the gravitational one, the effective
metric. In this theory, two horizons emerge, known as the apparent and sonic
horizon, related to the collapse of the gravitational and the effective metric,
respectively. For numerical purposes, we will focus on a particular Lagrangian
K(X) = X + βX2
, and study the formation and universal structure dynamics of
the horizons at the threshold of the formation of these objects.
However, the addition of scalar degrees of freedom is not the only alternative.
Higher dimensions, supergravity and string theories naturally lead to additional
scalar and vector fields in the action when we consider the low-energy limit of
such theories. To construct viable theories of gravity with additional fundamental
fields, a review of the stability of black holes must be a necessary task to ensure
the absence of Ostrogradsky instability. In this sense, we study the classical
stability of the generalized Einstein-Maxwell-Scalar theory. We will develop a
perturbation formalism on a static and spherically symmetric background and
show that black holes are generically stable under certain conditions.
Finally, we will discuss a physical observable of black holes, namely the quasinormal modes for pure Lovelock black holes in some particular dimensions. It is
well-known that the set of quasinormal modes frequencies depends on the intrinsic parameter of the black hole. We will analyze how the spacetime dimension
affects the characteristic time and oscillation frequency of the ringdown signal,
the final state of a perturbed black hole.
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Keywords
COLAPSO GRAVITACIONAL , TEORÍA DE LA PERTURBACIÓN , ESTABILIDAD DE AGUJEROS NEGROS