HET-Discovery seminar by Manuel Meyer – University of Copenhagen

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HET-Discovery seminar by Manuel Meyer

Astrophysical searches for axions and axionlike particles at gamma-ray energies

Abstract:
Axions and axionlike particles (ALPs) are dark-matter candidates that occur in a variety of extensions of the Standard Model. They could be detected through their coupling to photons in external electromagnetic fields. Due to the ubiquitous presence of magnetic fields in the Universe, astrophysical sources are particularly well suited to search for traces of these particles. 
Here, I give an overview over axion and ALP searches at gamma-ray energies. In particular, I will present recent constraints on the photon-ALP coupling with the Fermi Large Area Telescope using observations of NGC 1275, the central galaxy of the Perseus cluster. The high magnetic field in this galaxy cluster results in the strongest bounds to date in the ALP mass range between 0.5 and 20 neV that surpass the sensitivity of future dedicated laboratory experiments. In light of these limits, the possibility that ALPs alter the opacity of the Universe for gamma rays will be reviewed. I will also give an outlook on future gamma-ray searches for axions and ALPs. I will focus on the sensitivity of current and future gamma-ray instruments to detect an ALP induced gamma-ray burst from a Galactic core-collapse supernova. In such an event, ALPs would be produced in the stellar medium via the Primakoff effect and convert into gamma rays in the Galactic magnetic field.