Searches for Axion-Like Particles with NGC1275: Current and Future Bounds

Galaxy clusters contain large magnetic fields that make them excellent targets to search for ultralight Axion-Like Particles (ALPs). ALP-photon interconversion imprints quasi-sinusoidal oscillations on the X-ray spectra of point sources in or behind the cluster. The absence of substantial oscillations allows us to place bounds on $g_{a \gamma \gamma}$. Here the bounds from the {\it Chandra} X-ray observations of NGC1275 are presented, as well as those predicted for the {\it Athena} X-ray observatory, due to launch in 2028.