Detecting neutral hydrogen in emission at redshift z ~ 1

Understand

We use a large N-body simulation to examine the detectability of HI in emission at redshift z ~ 1, and the constraints imposed by current observations on the neutral hydrogen mass function of galaxies at this epoch.

• We consider three different models for populating dark matter halos with HI, designed to encompass uncertainties at this redshift.
• These models are consistent with recent observations of the detection of HI in emission at z ~ 0.8.
• Whilst detection of 21 cm emission from individual halos requires extremely long integrations with existing radio interferometers, such as the Giant Meter Radio Telescope (GMRT), we show that the stacked 21 cm signal from a large number of halos can be easily detected.