Abstract
One of the explanations for the recent EDGES-LOW band 21-cm measurements of a
strong absorption signal around 80~MHz is the presence of an excess radio
background to the Cosmic Microwave Background (CMB). Such excess can be
produced by the decay of unstable particles into small mass dark photons which
have a non-zero mixing angle with electromagnetism. We use the EDGES-LOW band
measurements to derive joint constraints on the properties of the early
galaxies and the parameters of such a particle physics model for the excess
radio background. A Bayesian analysis shows that a high star formation
efficiency and an X-ray luminosity of $1-2 10^41 erg ~s^-1 ~
Mpc^-3$ are required along with a suppression of star formation in halos with
virial temperatures $210^4$ K. The same analysis also suggests
a 68 percent credible intervals for the mass of the decaying dark matter
particles, it's lifetime, dark photon mass and the mixing angle of the dark and
ordinary photon oscillation of $10^-3.5, 10^-2.4$ eV, $10^1.1,
10^2.7\tau_U$, $10^-12.2, 10^-10$ eV and $10^-7, 10^-5.6$
respectively. This implies an excess radio background which is $5.7$
times stronger than the CMB around 80~MHz. This value is a factor $3$
higher than the previous predictions which used a simplified model for the
21-cm signal.
Users
Please
log in to take part in the discussion (add own reviews or comments).