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Abstract: Gravastars have been recently proposed as potential alternatives to explainthe astrophysical phenomenology traditionally associated to black holes,raising the question of whether the two objects can be distinguished at all.Leaving aside the debate about the processes that would lead to the formationof a gravastar and the astronomical evidence in their support, we here addresstwo basic questions: Is a gravastar stable against generic perturbations? Ifstable, can an observer distinguish it from a black hole of the same mass? Toanswer these questions we construct a general class of gravastars and determinethe conditions they must satisfy in order to exist as equilibrium solutions ofthe Einstein equations. For such models we perform a systematic stabilityanalysis against axial-perturbations, computing the real and imaginary parts ofthe eigenfrequencies. Overall, we find that gravastars are stable to axialperturbations, but also that their quasi-normal modes differ from those of ablack hole of the same mass and thus can be used to discern, beyond dispute, agravastar from a black hole.



Author: Cecilia B. M. H. Chirenti, Luciano Rezzolla

Source: https://arxiv.org/







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