Erlangen 2026 – wissenschaftliches Programm

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GR: Fachverband Gravitation, Relativistische Astrophysik und Kosmologie

GR 6: Black Holes I

GR 6.3: Vortrag

Dienstag, 17. März 2026, 16:45–17:00, KH 02.012

On the formation of black-hole mimickers within General Relativity — •Daniel Jampolski¹ and Luciano Rezzolla^1,2,3 — ¹Institut für Theoretische Physik, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany — ²School of Mathematics, Trinity College, Dublin 2, Ireland — ³CERN, Theoretical Physics Department, 1211 Geneva 23, Switzerland

Regular black holes and horizonless black-hole mimickers offer mathematically consistent alternatives to address the challenges posed by standard black holes. However, the formation mechanism of these alternative objects is still largely unclear and constitutes a significant open problem since understanding their dynamical formation represents a first step to assess their existence. We here investigate, for the first time and without invoking deviations from general relativity, the dynamical formation of a well-known horizonless black-hole mimicker, namely, a gravastar. More specifically, starting from the collapse of a uniform dust sphere as in the case of the Oppenheimer-Snyder collapse, we demonstrate that, under suitable conditions, a gravastar can form from the nucleation and expansion of a de-Sitter region with initial zero size at the center of the collapsing sphere. Furthermore, the de-Sitter expansion naturally slows down near the Schwarzschild radius, where it meets the collapsing dust surface and gives rise to a static equilibrium. Interestingly, we also find a maximum initial compactness of the collapsing star of C= 3/8, above which the collapse to a black hole is inevitable.

Keywords: dynamics; formation; collapse; gravastars; compactness