Astroparticle Seminar

The Dark Side of the Sun: Searching for Solar Axions with Helioscopes

Julia K. Vogel

LLNL

The puzzling nature of dark matter (DM), which is expected to contribute about 25% to the mass of the universe, remains one of the fundamental questions in cosmology. Axions are one of the current leading candidates for the hypothetical, non-baryonic DM. Especially in the light of LHC slowly closing in on WIMP searches with latest results placing strong restrictions on simplified and constrained models of supersymmetry, axions and axion-like particles (ALPs) provide a viable alternative approach to solving the dark matter problem. The fact that makes them very appealing is that they were initially introduced to solve a long-standing QCD problem in the Standard Model of particle physics.

The CERN Axion Solar Telescope (CAST) is an axion helioscope searching for solar axions, which could be produced in the core of the Sun via the Primakoff effect. In order to look for axions originating from the Sun, CAST uses a decommissioned LHC prototype magnet. In its 10 m long magnetic field region of 9 Tesla, axions could be reconverted into X-ray photons. Different X-ray detectors are installed on both ends of the magnet, which is mounted on a structure built to follow the Sun during sunrise and sunset for a total of about 3 hours per day. During CAST~Rs physics program different axions masses were studied by either evacuating the magnetic field region or filling it with a buffer gas (⁴He or ³He).

In this talk the latest CAST results will be presented and an outlook will be given on future axion experiments such as the International AXion Observatory (IAXO).