γhosts from the past: reheating neutron stars with supernova-sourced ALPs
Abstract
Axion-like particles (ALPs) can be copiously produced in the hot and dense environment of a core-collapse supernova. If their mass is within an order of magnitude of the supernova temperature, a non-negligible fraction of them will remain gravitationally bound to the neutron star remnant. This basin of ALPs can then decay to photons over the lifetime of the neutron star, thereby reheating it. Using the measured luminosities of several neutron stars, we close multiple windows in ALP parameter space while also satisfying the SN 1987A cooling constraint on the ALP-nucleon coupling. In particular, using the 35000 K upper limit on the temperature of the coldest neutron star observed, PSR J2144−3933, we derive the strongest upper limits on the ALP-photon coupling for 1−400 MeV ALP masses. Ceilings on these limits arising from ALP decays occurring within the neutron star lifetime may be overcome by using younger neutron stars such as the one in Cas A, probing couplings orders of magnitude higher. Observations of a 2000 K-hot neutron star in infrared observatories such as the James Webb Space Telescope could reach ALP-photon couplings three orders lower and ALP masses one order lower than our current limits.
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BibTeX
@misc{bose2026γhosts,
title = {{$γ$hosts from the past: reheating neutron stars with supernova-sourced ALPs}},
author = {Debajit Bose and Sougata Ganguly and Tanmoy Kumar and Nirmal Raj},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.30255},
eprint = {2610.30255},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.30255},
}
RIS
TY - UNPB
TI - γhosts from the past: reheating neutron stars with supernova-sourced ALPs
AU - Debajit Bose
AU - Sougata Ganguly
AU - Tanmoy Kumar
AU - Nirmal Raj
PY - 2026
DA - 2026/10/21
PB - arXiv
DO - 10.48550/arxiv.2610.30255
UR - https://arxiv.org/abs/2610.30255
AB - Axion-like particles (ALPs) can be copiously produced in the hot and dense environment of a core-collapse supernova. If their mass is within an order of magnitude of the supernova temperature, a non-negligible fraction of them will remain gravitationally bound to the neutron star remnant. This basin of ALPs can then decay to photons over the lifetime of the neutron star, thereby reheating it. Using the measured luminosities of several neutron stars, we close multiple windows in ALP parameter space while also satisfying the SN 1987A cooling constraint on the ALP-nucleon coupling. In particular, using the 35000 K upper limit on the temperature of the coldest neutron star observed, PSR J2144−3933, we derive the strongest upper limits on the ALP-photon coupling for 1−400 MeV ALP masses. Ceilings on these limits arising from ALP decays occurring within the neutron star lifetime may be overcome by using younger neutron stars such as the one in Cas A, probing couplings orders of magnitude higher. Observations of a 2000 K-hot neutron star in infrared observatories such as the James Webb Space Telescope could reach ALP-photon couplings three orders lower and ALP masses one order lower than our current limits.
ER -