The Effects of Population III X-ray and Radio Backgrounds on the Cosmological 21-cm Signal

Understand

We investigate the effects of Population III (Pop III) stars and their remnants on the cosmological 21-cm global signal.

• By combining a semi-analytic model of Pop III star formation with a global 21-cm simulation code, we investigate how X-ray and radio emission from accreting Pop III black holes may affect both the timing and depth of the 21-cm absorption feature that follows the initial onset of star formation during the Cosmic Dawn.
• We compare our results to the findings of the EDGES experiment, which has reported the first detection of a cosmic 21-cm signal.
• In general, we find that our fiducial Pop III models, which have peak star formation rate densities of $\sim 10^{-4}$ M$_\odot$ yr$^{-1}$ Mpc$^{-3}$ between $z \sim 10$ and $z \sim 15$, are able to match the timing of the EDGES signal quite well, in contrast to models that ignore Pop III stars.