Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2610.29857

Semiclassical effects on ultramassive spacetimes

Valentin Boyanov·Luis J. Garay·Alberto García Martín-Caro·Gerardo García-Moreno
View original source ↗Read source document ↗Export metadata ↓

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.

Explore related subjects

gr-qchep-th

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Valentin Boyanov, Luis J. Garay, Alberto García Martín-Caro, Gerardo García-Moreno. 2026-10-21. Semiclassical effects on ultramassive spacetimes. https://arxiv.org/abs/2610.29857

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Ellis-Bronnikov Wormhole Shadows with Spherically Symmetric Accretion Flow

We investigate the observational differences between the Ellis--Bronnikov (EB) wormhole and the Schwarzschild black hole (BH) by performing general relativistic radiative transfer (GRRT) simulations. We consider a spherically symmetric steady-state accretion flow and perform GRRT simulations incorporating synchrotron emission. For both the EB wormhole and the Schwarzschild BH, the simulated images consist of a central shadow region and a bright photon ring. We find that both the shadow region and the photon ring of the EB wormhole are brighter than those of the Schwarzschild BH. These differences arise from the absence of an event horizon in the EB wormhole, allowing the emission from the accreting matter around and beyond the throat to contribute to the intensity. We also compare the simulated images with the Event Horizon Telescope (EHT) observations of M87*. Although the total flux and the ring diameter are comparable with the EHT results, our models with the spherically symmetric accretion flow cannot reproduce the deep central brightness depression observed by the EHT, for both the EB wormhole and the Schwarzschild BH. This indicates that a non-spherical accretion flow is required for a detailed comparison with the EHT image.

gr-qc↗
arXiv2026

Linearised gravitational radiation in de Sitter spacetime at all multipole orders

We derive the linearised gravitational waves generated by a localised matter source in the Poincare patch of de Sitter spacetime at arbitrary multipole order. The linearised de Sitter problem is mapped exactly to an auxiliary flat-space problem in harmonic gauge, with a conserved source built from the physical stress tensor. This allows us to use the multipole expansion of Damour and Iyer verbatim, and yields the exterior metric at all orders in terms of two families of radiative multipole moments given as explicit integrals of the physical stress tensor. The de Sitter tail is absorbed entirely into the auxiliary stress tensor, so that neither the moments nor the canonical exterior metric carry an integral over the past history of the source. As a check, we recover the known quadrupolar metric: in the quadrupolar truncation it is our canonical field up to a residual gauge transformation, which we construct explicitly.

gr-qc↗
arXiv2026

Nonlinear Response of Schwarzschild Black Holes at Arbitrary Perturbative Order

We establish recursive integration-by-parts identities that symbolically reduce the inhomogeneous solutions of the Regge-Wheeler-Zerilli equation to a small set of master integrals, yielding the nonlinear response kernels of Schwarzschild black holes at arbitrary perturbative order. We further derive a closed ODE system that enables rapid, accurate, and stable numerical evaluation of these master integrals. To demonstrate our result, we compute quadratic, cubic, and quartic quasinormal-mode coupling coefficients as special cases of the response kernels.

gr-qc↗