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SUMMARY:Tightest constraints on very-light Axion-Like Particles (ALPs) usi
 ng the X-ray spectrum of the H1821+643 cluster-hosted quasar - Julia Sisk 
 Reynes
DTSTART:20220309T131500Z
DTEND:20220309T134500Z
UID:TALK170954@talks.cam.ac.uk
CONTACT:Hannah Uebler
DESCRIPTION:Axion-Like Particles (ALPs) are a well-motivated extension to 
 the Standard Model of particle physics. In the presence of a magnetised pl
 asma such as the intracluster medium (ICM) in rich cool-core clusters of g
 alaxies\, light may inter-convert into ALPs of a given mass m as determine
 d by the ALP-photon coupling strength. At X-ray energies\, we would expect
  photon-ALP oscillations to induce energy-dependent modulations on the int
 rinsic spectra of central AGN as their quanta travel through the magnetise
 d ICM. This can be used to place bounds on the ALP-photon coupling for ver
 y-light ALPs\, that is\, of log(m/eV) < -12\, given a model for the ICM ma
 gnetic field. Using a cell-based approach for the latter\, I will present 
 the tightest constraints to-date on such ALPs\, which we have inferred fro
 m a deep Chandra grating observation of the extraordinarily luminous radio
 -quiet cluster-hosted quasar H1821+643. I will also present the exciting p
 rospects for cluster-ALP studies given the unprecedented energy resolution
  of the next-generation X-ray telescope Athena.
LOCATION:The Hoyle Lecture Theatre + Zoom 
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