Hunting for axions: Shining light through (cosmic) walls

Axions and axion-like particles are hypothetical particles that could explain the cold dark matter as well as the non-observation of an electric dipole moment of the neutron. If these particles existed, they could reveal themselves through  either an oscillation into photons in the presence of external magnetic fields or the decay into two photons. Both possibilities can be probed with observations of distant sources of energetic gamma rays. In this talk, I will review the motivation for axions and how we can search for their signatures using observations with the Fermi Large Area Telescope and Cherenkov detectors. In particular, I will discuss recent searches using flat spectrum radio quasars, an axion contribution to the extra galactic background light, and axions in the context of the observation of gamma rays beyond tens of TeV from the brightest ever observed gamma-ray burst. If time permits, I will also briefly touch upon the ALPS II experiment, which aims to produce and subsequently detect axions in the laboratory. The first science run of ALPS II is scheduled for later this year.

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