Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · 2606.02722

Asymptotically-FLRW$_3$ spacetimes

Andrea Campoleoni·Arnaud Delfante·Marc Geiller·Nicolas Maindiaux
View original source ↗Read source document ↗Export metadata ↓

Abstract

We introduce three-dimensional asymptotically-FLRW spacetimes as a simplified setting in which to study asymptotic symmetries and radiation in cosmology. Their asymptotic symmetry group is $\text{BMS}_3^k$, a one-parameter deformation of $\text{BMS}_3$ controlled by the matter equation of state with parameter $k$, in line with the four-dimensional construction of Bonga and Prabhu. We analyze in detail the case of a scalar field matter source, which allows us to fully characterize the solution space and the boundary charges. In particular, we point out that the proper identification of the Bondi mass and angular momentum aspects in the metric requires a careful analysis which had not been laid out so far, even in the existing four-dimensional literature. When superrotations are present, the model exhibits subtleties similar to those appearing when dealing with ''generalized BMS'' asymptotic symmetries in the four-dimensional case, and this requires a covariant definition of the news. We identify covariant notions of news, as well as of mass and angular momentum aspects by studying the vacuum structure, namely the orbits of the vacuum solution under finite $\text{BMS}_3^k$ transformations, and study the Wald-Zoupas prescription for the charges. We also show that these covariant aspects naturally appear in the Cotton scalars, which are the three-dimensional analogues of the Weyl scalars. Finally, we use these quantities to provide a first example of exactly conserved non-linear Newman-Penrose charges in three-dimensional gravity.

Explore related subjects

gr-qchep-th

Keep this discovery

BibTeXRIS

Andrea Campoleoni, Arnaud Delfante, Marc Geiller, Nicolas Maindiaux. 2026-06-01. Asymptotically-FLRW$_3$ spacetimes. https://arxiv.org/abs/2606.02722

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

KEEP EXPLORING

Related papers

arXiv2026

Electrovacuum Black Hole Uniqueness

We prove the black hole uniqueness conjecture in the axially symmetric, stationary, electrovacuum setting, subject to the refined asymptotic analysis of the associated singular harmonic maps, which includes an analyticity hypothesis at the axes. More precisely, it is shown that any asymptotically flat solution of the Einstein--Maxwell equations in this class, with more than one black hole horizon component is either: Majumdar--Papapetrou, up to a duality rotation, in which case all logarithmic angle defects vanish, or every finite axis rod logarithmic angle defect is strictly negative and hence every interaction force is strictly attractive. The proof extends the singular harmonic map method used for vacuum Kerr uniqueness in [18].

gr-qc↗
arXiv2026

Constraining Modified Mass-to-Horizon Cosmology Through Primordial Inflationary Observables

We investigate slow-roll inflation in a modified cosmological framework inspired by a generalized mass-to-horizon relation (MHR), $M=\gamma {c^2 L^n}/{G}$, where $n$ is a real parameter and $\gamma$ a dimensional constant. Using Padmanabhan's emergence paradigm, we derive the modified Friedmann equations for a flat FRW universe and analyze the dynamics of a canonical scalar field (inflaton) under the slow-roll approximation. We study the resulting inflationary phenomenology for power-law and Starobinsky potentials. For power-law potentials, the MHR modification fails to reconcile these models with current CMB constraints on $r$ and $n_s$. In contrast, Starobinsky inflation exhibits significant sensitivity to deviations from $n=1$. A perturbative analysis ($n=1+\Delta$) yields corrections to inflationary observables. We observe that the scalar power-spectrum normalization, under a fixed-Starobinsky prescription, imposes the stringent constraint $0.960 \lesssim n \lesssim 1.040$ for $N=60$ efolds. This is considerably tighter than spectral-index bounds. Our results establish inflation, particularly Starobinsky-like models, as a sensitive probe of generalized horizon thermodynamics and departures from standard MHR scaling.

gr-qc↗
arXiv2026

Improving the Sensitivity of Gravitational Wave Detection with Weighted Conformal Prediction

In the last decade, kilometre-scale interferometric gravitational-wave detectors have observed hundreds of compact binary mergers, the majority of which are binary black holes. However, the data are noise-dominated, and multiple independent search algorithms (pipelines) are used to enhance sensitivity and improve robustness. Rather than the standard approach of selecting the most significant pipeline output, we combine the outputs from all pipelines using a conformal prediction-based framework to provide statistically rigorous confidence estimates for candidate events. While combining pipelines improves sensitivity and ranking robustness, it requires a principled statistical framework that remains valid as data properties evolve across observing runs. A key challenge is distribution shifts between simulated datasets used for training and calibration and the real, unlabelled, observations used for testing, which can invalidate coverage guarantees and bias confidence estimates. In this work, we address this challenge by incorporating likelihood-ratio reweighting into our conformal prediction framework to account for covariate shift. Using mock datasets containing simulated signals, we demonstrate that weighted conformal prediction restores well-calibrated coverage under covariate shift and increases the confidence of events near the detection threshold, recovering true signals that would otherwise be missed.

gr-qc↗