Tightest constraints on very-light Axion-Like Particles (ALPs) using the X-ray spectrum of the H1821+643 cluster-hosted quasar

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• Julia Sisk Reynes
• Wednesday 09 March 2022, 13:15-13:45
• The Hoyle Lecture Theatre + Zoom .

If you have a question about this talk, please contact Hannah Uebler.

Axion-Like Particles (ALPs) are a well-motivated extension to the Standard Model of particle physics. In the presence of a magnetised plasma such as the intracluster medium (ICM) in rich cool-core clusters of galaxies, light may inter-convert into ALPs of a given mass m as determined by the ALP -photon coupling strength. At X-ray energies, we would expect photon-ALP oscillations to induce energy-dependent modulations on the intrinsic spectra of central AGN as their quanta travel through the magnetised ICM . This can be used to place bounds on the ALP -photon coupling for very-light ALPs, that is, of log(m/eV) < -12, given a model for the ICM magnetic field. Using a cell-based approach for the latter, I will present the tightest constraints to-date on such ALPs, which we have inferred from a deep Chandra grating observation of the extraordinarily luminous radio-quiet cluster-hosted quasar H1821 +643. I will also present the exciting prospects for cluster-ALP studies given the unprecedented energy resolution of the next-generation X-ray telescope Athena.

This talk is part of the Institute of Astronomy Seminars series.

This talk is included in these lists:

• Cambridge Astronomy Talks
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• Cosmology, Astrophysics and General Relativity
• Institute of Astronomy Seminars
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