• line emission
• cosmology
• intensity mapping

We studied the 3D fluctuations in Ly-alpha emission with a particular focus on the epoch of reionization. Our goal was to assess both the feasibility of an intensity mapping survey and the physics that it could probe.

We assumed a reionization scenario dominated by UV galaxy emission and considered separately population II and population III stars. We developed an analytical model for the star formation rate, then we calculated the reionization history and the Ly-alpha emission accordingly. We computed the 3D power spectrum of the line fluctuations, finding that the dominant source is the IGM emission from scattering of redshifted Lyman photons. The fluctuations trace the star formation rate, therefore a Ly-alpha intensity mapping can probe both the large scale galaxy distribution and the star formation history.

Then we considered the prospects of an intensity mapper for measuring the fluctuations, dealing also with the foreground removal. We found that a small space instrument can probe the large scale structure up to z = 7. Therefore, Ly-alpha intensity mapping is an extremely powerful tool that can observe the large scale structure of the galaxy distribution in the late stages of the epoch of reionization.