Speaker
Description
The Epoch of Reionization (EoR) marks the last major phase transition of the Universe, during which the Intergalactic Medium (IGM) evolves from being predominantly neutral to fully ionized. The line intensity mapping (LIM) of different spectral lines originating from this era are direct and most promising probes for the EoR. The two spectral lines that stand out for the LIM surveys of the EoR are the redshifted 21-cm line from neutral hydrogen (HI) and singly ionized carbon (CII) line from star forming regions of the early galaxies. The SKA-Low and FYST are the two upcoming instruments that will be capable of performing LIM surveys of the EoR using 21-cm and CII lines respectively. During the EoR, the 21-cm signal predominantly comes from the HI in the IGM, whereas the contribution to this signal from the HI in the ISM is negligible. This changes by the end of reionization when almost all of the IGM is ionized, then the 21-cm signal originates mostly from the galaxies. We propose that by probing the nature of correlation between the 21-cm and CII LIM signals using the surveys to be performed by SKA-Low and FYST one would able to constrain the end of reionization redshift in a robust manner, which may not be possible via other probes of the EoR e.g. quasar absorption spectra, CMBR Thomson scattering optical depth etc. We specifically focus on the cross-power spectrum statistics to perform this analysis and also make forecasts for future SKA-Low and FYST surveys.
