Inflaton Accretion onto Primordial Black Holes During Reheating

Fuente: arXiv
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Main Authors: Kalita, Jitumani, Maity, Debaprasad
Format: Preprint
Published: 2026
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author Kalita, Jitumani
Maity, Debaprasad
author_facet Kalita, Jitumani
Maity, Debaprasad
contents Primordial Black Holes (PBHs) forming prior to Big Bang Nucleosynthesis evolve during the reheating epoch, an environment dominated by an oscillating inflaton field decaying into a relativistic thermal bath. In this work, we track the complete lifecycle of PBHs within this coupled inflaton-radiation background. Utilizing $α$-attractor E-models, we analytically anchor the reheating initial conditions directly to Cosmic Microwave Background observations. By matching exact scalar field solutions in a Schwarzschild spacetime to the cosmological far-zone, we derive the cycle-averaged mass accretion rate and couple it to the growing radiation bath. We find that this combined accretion induces a highly non-linear enhancement of the final PBH mass. Because the Hawking evaporation timescale scales cubically with mass, PBHs forming near their critical runaway limits experience a massive extension of their lifespans. Surviving deeper into the radiation-dominated era triggers a multi-order-of-magnitude amplification in their emitted Stochastic Gravitational Wave Background (SGWB).
format Preprint
id arxiv_https___arxiv_org_abs_2605_19825
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Inflaton Accretion onto Primordial Black Holes During Reheating
Kalita, Jitumani
Maity, Debaprasad
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
Primordial Black Holes (PBHs) forming prior to Big Bang Nucleosynthesis evolve during the reheating epoch, an environment dominated by an oscillating inflaton field decaying into a relativistic thermal bath. In this work, we track the complete lifecycle of PBHs within this coupled inflaton-radiation background. Utilizing $α$-attractor E-models, we analytically anchor the reheating initial conditions directly to Cosmic Microwave Background observations. By matching exact scalar field solutions in a Schwarzschild spacetime to the cosmological far-zone, we derive the cycle-averaged mass accretion rate and couple it to the growing radiation bath. We find that this combined accretion induces a highly non-linear enhancement of the final PBH mass. Because the Hawking evaporation timescale scales cubically with mass, PBHs forming near their critical runaway limits experience a massive extension of their lifespans. Surviving deeper into the radiation-dominated era triggers a multi-order-of-magnitude amplification in their emitted Stochastic Gravitational Wave Background (SGWB).
title Inflaton Accretion onto Primordial Black Holes During Reheating
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2605.19825