2008/08/29 by Cecilia Chirenti, Cecilia B. M. H. Chirenti, Luciano Rezzolla · 2 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Cosmology and Gravitation Theories #Solar and Space Plasma Dynamics #gr-qc
paper · pdf · doi:10.1103/physrevd.78.084011
published as Phys.Rev.D78:084011,2008 · 10 pages, 7 figures
arxiv created 2008/08/29 · openalex publication_date 2008/10/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
The ergoregion instability is known to affect very compact objects that rotate very rapidly and do not possess a horizon. We present here a detailed analysis on the relevance of the ergoregion instability for the viability of gravastars. Expanding on some recent results, we show that not all rotating gravastars are unstable. Rather, stable models can be constructed also with J/M2\ensuremath∼1, where J and M are the angular momentum and mass of the gravastar, respectively. The genesis of gravastars is still highly speculative and fundamentally unclear if not dubious. Yet, their existence cannot be ruled out by invoking the ergoregion instability. For the same reason, not all ultracompact astrophysical objects rotating with J/M2\ensuremath\lesssim1 are to be considered necessarily black holes.