Abstract: Active galactic nuclei (AGNs) are extreme astrophysical environment that result in copious emission of X-rays. I describe how large archival datasets from X-ray telescopes can be used to search for new physics using the X-ray spectrum of AGNs. The two examples discussed are axion-like particles and dark matter. For axion-like particles, intervening magnetic fields can lead to photon-axion conversion and a characteristic form of energy-dependent spectral modulation. I describe our recent analysis of archival Chandra data of NGC1275, the central Active Galactic Nucleus of the Perseus cluster. I describe the bounds on axion-like particles this gives. We find at > 4 sigma a dip in the spectrum at (3.54 +- 0.02) keV, the same energy as the unidentified 3.5 keV line seen from various astrophysical environments. This motivates a scenario of Fluorescent Dark Matter, resonantly absorbing and re-emitting 3.54 keV photons.
This seminar is supported by Portuguese Funds through the CIDMA - Centre for Research and Development in Mathematics and Applications, and the Portuguese Foundation for Science and Technology ("FCT" - Fundação para a Ciência e a Tecnologia), within the project UID/MAT/04106/2013.