dc.contributor.author Matthews, James dc.contributor.author Reynolds, Christopher dc.contributor.author Marsh, MC David dc.contributor.author Sisk-Reynes, Julia dc.contributor.author Rodman, Payton E dc.date.accessioned 2022-05-09T11:03:49Z dc.date.available 2022-05-09T11:03:49Z dc.date.issued 2022-05-01 dc.date.submitted 2022-01-19 dc.identifier.issn 0004-637X dc.identifier.other apjac5625 dc.identifier.other ac5625 dc.identifier.other aas37208 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/336892 dc.description.abstract Axion-like particles (ALPs) are a well-motivated extension to the standard model of particle physics, and X-ray observations of cluster-hosted AGN currently place the most stringent constraints on the ALP coupling to electromagnetism, $g_{a \gamma}$, for very light ALPs ($m_a\lesssim10^{-11}$ eV). We revisit limits obtained by Reynolds et al. (2020) using Chandra X-ray grating spectroscopy of NGC 1275, the central AGN in the Perseus cluster, examining the impact of the X-ray spectral model and magnetic field model. We also present a new publicly available code, ALPro, which we use to solve the ALP propagation problem. We discuss evidence for turbulent magnetic fields in Perseus and show that it can be important to resolve the magnetic field structure on scales below the coherence length. We re-analyse the NGC 1275 X-ray spectra using an improved data reduction and baseline spectral model. We find the limits are insensitive to whether a partially covering absorber is used in the fits. At low $m_a$ ($m_a\lesssim10^{-13}$ eV), we find marginally weaker limits on $g_{a \gamma}$ (by $0.1-0.3$ dex) with different magnetic field models, compared to Model B from Reynolds et al. (2020). A Gaussian random field (GRF) model designed to mimic $\sim50$ kpc scale coherent structures also results in only slightly weaker limits. We conclude that the existing Model B limits are robust assuming that $\beta_{\rm pl}\approx100$, and are insensitive to whether cell-based or GRF methods are used. However, astrophysical uncertainties regarding the strength and structure of cluster magnetic fields persist, motivating high sensitivity RM observations and tighter constraints on the radial profile of $\beta_{\rm pl}$. dc.language en dc.publisher American Astronomical Society dc.subject 330 dc.subject High-Energy Phenomena and Fundamental Physics dc.title How Do Magnetic Field Models Affect Astrophysical Limits on Light Axion-like Particles? An X-Ray Case Study with NGC 1275 dc.type Article dc.date.updated 2022-05-09T11:03:48Z prism.issueIdentifier 1 prism.publicationName ASTROPHYSICAL JOURNAL prism.volume 930 dc.identifier.doi 10.17863/CAM.84311 dcterms.dateAccepted 2022-02-15 rioxxterms.versionofrecord 10.3847/1538-4357/ac5625 rioxxterms.version VoR rioxxterms.licenseref.uri http://creativecommons.org/licenses/by/4.0/ dc.contributor.orcid Matthews, James [0000-0002-3493-7737] dc.contributor.orcid Reynolds, Christopher [0000-0002-1510-4860] dc.identifier.eissn 1538-4357 dc.publisher.url http://dx.doi.org/10.3847/1538-4357/ac5625 pubs.funder-project-id Engineering and Physical Sciences Research Council (EP/P020259/1) pubs.funder-project-id Science and Technology Facilities Council (ST/S000623/1) pubs.funder-project-id European Commission Horizon 2020 (H2020) ERC (834203) pubs.funder-project-id STFC (ST/V50659X/1) pubs.funder-project-id Science and Technology Facilities Council (2442592) cam.issuedOnline 2022-05-05
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