Abstract:
Galaxy clusters represent excellent laboratories to search for Axion-Like Particles (ALPs). They contain magnetic fields which can induce
quasi-sinusoidal oscillations in the X-ray spectra of AGNs situated in or behind them. Ultra-deep Chandra observations of the Perseus cluster contain over 5 x 10^5 counts from the central NGC1275 AGN, and represent an extraordinary dataset for ALP searches. In this talk I will describe how we used these to search for spectral irregularities from the AGN. No irregularities were foundat the ~30% level, allowing us to place leading constraints on the ALP-photon mixing parameter g_a  <1.5 ◊ 10^12GeV^1  for ma < 10^-12 eV. I will move on to discuss the upcoming Athena X-ray Observatory, due for launch in 2028. The X-ray Integral Field Unit (X-IFU) instrument onboard will be far better able to constrain ALPs than Chandra, due to its excellent energy resolution. Using the SIXTE simulation software, we estimate that non-observation of spectral modulations for a 200ks observation of NGC1275 will constrain g_a <1.5 ◊ 10^13GeV^1, an order of magnitude improvement over that derived from Chandra data.

Please note the dates and locations for upcoming meetings:
upcoming:

Thu 28 Sep 2:00pm/ NE83/Great
Thu  5 Oct 2:00pm/ 37-252 Marlar
Thu 12 Oct 2:00pm/ NE83
Thu 19 Oct 2:00pm/ 37-252 Marlar
Thu 26 Oct 2:00pm/ 37-252 Marlar
Tue 31 Oct 2:00pm/ NE83  [tentative]
Thu  9 Nov 2:00pm/NE83
Thu 16 Nov 2:00pm/37-252 Marlar
Thu 30 Nov 2:00pm/37-252 Marlar