UCLA

One of the largest open questions in physics is the nature of dark matter. Among the proposed candidates are the axion and its associated family of axionlike particles (ALPs). I have worked with the South Pole Telescope (SPT), an experiment studying the cosmic microwave background (CMB), to search for evidence of ultralight ALP dark matter. ALPs in the 10^(−23) − 10^(−18) eV mass range behave as a classical field, the value of which oscillates on human-observable timescales of hours to years. This oscillation in turn induces an oscillation in the polarization angle of linearly-polarized photons traveling through the axion field. Using data captured with SPT-3G, the current receiver on SPT, I have used the CMB as a polarized light source with which to search for this oscillatory signal. In this dissertation, I will detail the methods and results of this search, setting competitive constraints and demonstrating the potential for future CMB experiments to make an ALP dark matter detection. I will then discuss my work developing a pipeline intended to increase the speed and ease with which CMB detectors can be tested, ensuring that these future experiments can reach their full discovery potential.