Axions: What can we learn from neutron stars and X-ray astronomy?

Prof. Kuver Sinha (Hosted by Dev), University of Oklahoma

Axion-like particles (ALPs) generically arise in compactifications of extra dimensions in string theory. They find applications in a variety of contexts: the strong CP problem, dark matter, and inflation. My talk will describe possible methods to probe them using the extreme astrophysical environments of neutron stars. The physics relies on the coupling of ALPs to photons, which can lead to appreciable mixing between the two particles in the presence of large background magnetic fields, for example those found in the vicinity of magnetars. The spectrum of such photons can range from the radio to the hard X-ray. I will specifically focus on the X-ray regime, and discuss a  particle physicist's wishlist of things that X-ray astronomy may be able to teach us about ALPs.