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Parameter estimation of gravitational wave echoes from exotic compact objects
Andrea Maselli, Sebastian H. Völkel, Kostas D. Kokkotas
Relativistic ultracompact objects without an event horizon may be able to form in nature and merge as binary systems, mimicking the coalescence of ordinary black holes. The postmer…
Oscillation modes of rapidly rotating neutron stars in scalar-tensor theories of gravity
Stoytcho S. Yazadjiev, Daniela D. Doneva, Kostas D. Kokkotas
We perform the first study of the oscillation frequencies of rapidly rotating neutron stars in alternative theories of gravity, focusing mainly on the fundamental -modes. We con…
Non-Schwarzschild black-hole metric in four dimensional higher derivative gravity: analytical approximation
K. Kokkotas, R. A. Konoplya, A. Zhidenko
Higher derivative extensions of Einstein gravity are important within the string theory approach to gravity and as alternative and effective theories of gravity. H. Lü, A. Perkins,…
Dark stars: gravitational and electromagnetic observables
Andrea Maselli, Pantelis Pnigouras, Niklas Gønlund Nielsen +2
Theoretical models of self-interacting dark matter represent a promising answer to a series of open problems within the so-called collisionless cold dark matter (CCDM) paradigm. In…
Ultra Compact Stars: Reconstructing the Perturbation Potential
Sebastian H. Völkel, Kostas D. Kokkotas
In this work we demonstrate how different semi-classical methods can be combined in a novel way to reconstruct the perturbation potential of ultra compact stars. Besides rather gen…
A Semi-analytic Study of Axial Perturbations of Ultra Compact Stars
Sebastian H. Völkel, Kostas D. Kokkotas
Compact object perturbations, at linear order, often lead in solving one or more coupled wave equations. The study of these equations was typically done by numerical or semi-analyt…