New Cosmological Constraints on Axions and Axion-Like Particles

We present constraints on the axion-photon coupling scale M for light axion-like particles by combining recent Supernova Type Ia data with the latest measurements of the Hubble expansion at redshifts between 0 and 2. Allowing for a coupling between axions and photons leads to a modification of the inferred luminosity distances for supernovae due to the conversion of photons to axions in the presence of intergalactic magnetic fields. We constrain such couplings by considering deviations from the luminosity-angular diameter distance relation d(L) = d(A) (1 + z)(2). We find that for intergalactic magnetic fields of order 1 nG, current supernova and Hubble expansion data rule out a region in the coupling scale M between 10(10) and 10(11) GeV.