Semiclassical effects on ultramassive spacetimes
Abstract
A recent work [Senovilla, Port. Math. 80 (2023)] has shown that accretion of matter by a Schwarzschild-de Sitter black hole can take this object beyond a critical limit where the event and cosmological horizons coalesce, transforming it into a collapsing universe resembling a Kantowski-Sachs cosmology. In these configurations, dubbed ``ultramassive spacetimes'', future asymptotic infinity and the event horizon associated with the black hole cease to exist. In this work, we take the first steps toward exploring semiclassical gravity effects on such geometries. In particular, we examine the fate of Hawking radiation in these backgrounds and analyze the behavior of the renormalized stress-energy tensor within the Polyakov approximation. We also explore the effect of semiclassical backreaction on the evolution of the horizons, focusing on cases in the vicinity of the extremal limit, and on the subsequent universal collapse.
Related
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BibTeX
@misc{boyanov2026semiclassical,
title = {{Semiclassical effects on ultramassive spacetimes}},
author = {Valentin Boyanov and Luis J. Garay and Alberto García Martín-Caro and Gerardo García-Moreno},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.29857},
eprint = {2610.29857},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.29857},
}
RIS
TY - UNPB
TI - Semiclassical effects on ultramassive spacetimes
AU - Valentin Boyanov
AU - Luis J. Garay
AU - Alberto García Martín-Caro
AU - Gerardo García-Moreno
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.29857
UR - https://arxiv.org/abs/2610.29857
AB - A recent work [Senovilla, Port. Math. 80 (2023)] has shown that accretion of matter by a Schwarzschild-de Sitter black hole can take this object beyond a critical limit where the event and cosmological horizons coalesce, transforming it into a collapsing universe resembling a Kantowski-Sachs cosmology. In these configurations, dubbed ``ultramassive spacetimes'', future asymptotic infinity and the event horizon associated with the black hole cease to exist. In this work, we take the first steps toward exploring semiclassical gravity effects on such geometries. In particular, we examine the fate of Hawking radiation in these backgrounds and analyze the behavior of the renormalized stress-energy tensor within the Polyakov approximation. We also explore the effect of semiclassical backreaction on the evolution of the horizons, focusing on cases in the vicinity of the extremal limit, and on the subsequent universal collapse.
ER -