Physics Beyond the Standard Model with Future X-ray Observatories: Projected Constraints on Very-Light Axion-Like Particles with $Athena$ and $AXIS$

Abstract

Axion-Like Particles (ALPs) are well-motivated extensions of the Standard Model of Particle Physics and a generic prediction of some string theories. X-ray observations of bright Active Galactic Nuclei (AGN) hosted by rich clusters of galaxies are excellent probes of very-light ALPs, with masses $\log (m_{\mathrm{a}}/\mathrm{eV})<-12.0$. We evaluate the potential of future X-ray observatories, particularly $Athena$ and the proposed $AXIS$, to constrain ALPs via observations of cluster-hosted AGN, taking NGC 1275 in the Perseus cluster as our exemplar. Assuming perfect knowledge of instrument calibration, we show that a modest exposure (200-ks) of NGC 1275 by $Athena$ permits us to exclude all photon-ALP couplings $g_{\mathrm{a}\gamma }>6.3\times 10^{-14}{\mathrm{GeV}}^{-1}$ at the 95% level, as previously shown by $Conlonetal.(2018)$, representing a factor of 10 improvement over current limits. We then proceed to assess the impact of realistic calibration uncertainties on the $Athena$ projection by applying a standard $Cash$ likelihood procedure, showing the projected constraints on $g_{\mathrm{a}\gamma }$ weaken by a factor of 10 (back to the current most sensitive constraints). However, we show how the use of a deep neural network can disentangle the energy-dependent features induced by instrumental miscalibration and those induced by photon-ALP mixing, allowing us to recover most of the sensitivity to the ALP physics. In our explicit demonstration, the machine learning applied allows us to exclude $g_{\mathrm{a}\gamma }>2.0\times 10^{-13}{\mathrm{GeV}}^{-1}$, complementing the projected constraints of next-generation ALP dark matter birefringent cavity searches for very-light ALPs. Finally, we show that a 200-ks $AXIS$/on-axis observation of NGC 1275 will tighten the current best constraints on very-light ALPs by a factor of 3.

22 pages, 10 figures, 3 tables. Accepted for publication at the Astrophysical Journal. Comments welcome

References in corpus (14)

• The Quiescent Intracluster Medium in the Core of the Perseus Cluster
• Revisiting the SN1987A gamma-ray limit on ultralight axion-like particles
• Turbulent Heating in Galaxy Clusters Brightest in X-rays
• Physics potential of the International Axion Observatory (IAXO)
• On the use of C-stat in testing models for X-ray spectra
• Resolved magnetic dynamo action in the simulated intracluster medium
• Magnetic Fields in the Center of the Perseus Cluster
• The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey I: Probing galaxy cluster magnetic fields with line of sight rotation measures
• Axion-like Particles Implications for High-Energy Astrophysics
• Projected bounds on ALPs from Athena
• Searching for Axion-Like Particles from Core-Collapse Supernovae with Fermi LAT's Low Energy Technique
• Probing the circumnuclear environment of NGC1275 with High-Resolution X-ray spectroscopy
• AGN X-ray Spectroscopy with Neural Networks
• How do Magnetic Field Models Affect Astrophysical Limits on Light Axion-like Particles? An X-ray Case Study with NGC 1275

Cited by in corpus (2)

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