Cosmological Neutron Stars Produce Diffuse Axion X-Ray Signatures

Fuente: arXiv
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Main Authors: Ning, Orion, Raman, Kailash, Safdi, Benjamin R.
Format: Preprint
Published: 2025
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author Ning, Orion
Raman, Kailash
Safdi, Benjamin R.
author_facet Ning, Orion
Raman, Kailash
Safdi, Benjamin R.
contents Axion-like particles can be abundantly produced through scattering processes in the cores of neutron stars (NSs). If they are ultralight ($m_a \lesssim 10^{-4}$ eV), then they can efficiently convert to detectable photons in the external NS magnetospheres, and if they are heavy ($m_a \gtrsim 1$ eV), then they can decay into photons before reaching Earth. In this work, we search for the resulting X-ray signatures from both of these channels summing over the $\textit{cosmological}$ NS population. We compare the predicted axion-induced X-ray signal to the cosmic X-ray background today as measured by a number of instruments such as NuSTAR, HEAO, Swift, and INTEGRAL. We model the axion-induced signal using NS cooling simulations and magnetic field evolution models. We find no evidence for axions and derive strong constraints for both ultralight and heavy axion scenarios, covering new parameter space for the axion-photon and axion-nucleon couplings. Our results rule out the axion-explanation of the Magnificent Seven X-ray excess from nearby isolated NSs.
format Preprint
id arxiv_https___arxiv_org_abs_2512_15849
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Cosmological Neutron Stars Produce Diffuse Axion X-Ray Signatures
Ning, Orion
Raman, Kailash
Safdi, Benjamin R.
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
Axion-like particles can be abundantly produced through scattering processes in the cores of neutron stars (NSs). If they are ultralight ($m_a \lesssim 10^{-4}$ eV), then they can efficiently convert to detectable photons in the external NS magnetospheres, and if they are heavy ($m_a \gtrsim 1$ eV), then they can decay into photons before reaching Earth. In this work, we search for the resulting X-ray signatures from both of these channels summing over the $\textit{cosmological}$ NS population. We compare the predicted axion-induced X-ray signal to the cosmic X-ray background today as measured by a number of instruments such as NuSTAR, HEAO, Swift, and INTEGRAL. We model the axion-induced signal using NS cooling simulations and magnetic field evolution models. We find no evidence for axions and derive strong constraints for both ultralight and heavy axion scenarios, covering new parameter space for the axion-photon and axion-nucleon couplings. Our results rule out the axion-explanation of the Magnificent Seven X-ray excess from nearby isolated NSs.
title Cosmological Neutron Stars Produce Diffuse Axion X-Ray Signatures
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2512.15849