arXiv subjects

Soham Acharya

Publications and source records attributed to Soham Acharya.

4 recordsLinked to original sources

arXiv2026

Stochastic Evolution of Primordial Black Holes to near-extremality in EFTs of Gravity

The search for dark matter candidates includes primordial black holes (PBHs) as possible constituents. Recent studies show that some PBHs can survive to the present epoch by gaining angular momentum through Hawking radiating photons and becoming extremal before complete evaporation. While this provides a plausible model in a two-derivative theory of gravity, additional issues arise in EFT-corrected theories of gravity. In such theories, a rapidly spinning black hole can lead to extremely high tidal forces on a near-horizon observer, with possible observational consequences. In this work, by modeling Hawking radiation as a biased random walk within an EFT of gravity, we show that nearly the same fraction of PBHs survives as in GR. We argue that the resultant near horizon tidal effects should be detectable in future gravitational-wave observables.

gr-qc↗

arXiv2026

Effect of ultralight dark matter on compact binary mergers

The growing catalogue of gravitational wave events enables a statistical analysis of compact binary mergers, typically quantified by the merger rate density. This quantity can be influenced by ambient factors, following which, in this work we have investigated the impact of dark matter environment on the merger statistics. We construct a baseline astrophysical model of compact binary mergers and extend it by incorporating a model of ultra light dark matter, which affects the orbital evolution of binaries through accretion and dynamical friction. Our analysis of the merged population of binary progenitors demonstrates that, compared to the baseline model, ULDM can significantly alter the merger statistics when its ambient density becomes larger than 104GeV/cm3. A comparison with the gravitational wave data from the GWTC-3 catalogue provides insight into potential observational signatures of the ULDM in merger events, leading to possible constraints on the existence and density of dark matter distribution in galaxies.

gr-qc↗

arXiv2025

EFT Corrections to Majumdar-Papapetrou Black Holes

Recent studies on extremal black holes within effective field theories (EFT) of gravity have revealed an intriguing phenomenon: tidal forces near the horizon experience significant enhancement due to EFT corrections, potentially leading to a breakdown of the EFT framework. In this work, we investigate this effect in a two-black-hole Majumdar-Papapetrou spacetime modified by four-derivative EFT correction terms. Our analysis shows that while the scaling exponents, which measure the strength of the tidal forces near the horizon, remain unchanged under EFT corrections in $D=4$, they decrease for higher dimensions, enhancing the near-horizon tidal forces. We find an expression for the EFT corrections to the scaling exponents till $D \le 10$ and demonstrate that the metric corrections can be structured such that only the near-horizon $AdS_2$ throat undergoes angle-dependent modifications, while the transverse $S^{D-2}$ sector remains unaffected.

gr-qc↗

arXiv2024

Non-existence of short hairs for static black holes

The black hole no-short hair theorem establishes a universal lower bound on the extension of hairs outside any 4-dimensional spherically symmetric black hole solutions. We generalise this theorem beyond spherical symmetry, specifically for static, axisymmetric hairy black hole solutions and prove that the ``hairosphere'' must extend beyond the radial extent of the innermost light ring.

gr-qc↗