Abstract
We report on the search for spectral irregularities induced by oscillations between photons and axionlike-particles (ALPs) in the -ray spectrum of NGC 1275, the central galaxy of the Perseus cluster. Using 6 years of Fermi Large Area Telescope data, we find no evidence for ALPs and exclude couplings above for ALP masses at 95% confidence. The limits are competitive with the sensitivity of planned laboratory experiments, and, together with other bounds, strongly constrain the possibility that ALPs can reduce the -ray opacity of the Universe.
- Received 27 November 2015
DOI:https://doi.org/10.1103/PhysRevLett.116.161101
© 2016 American Physical Society