Intensity Mapping of H Α , H Β , [ Oii ] and [

Intensity mapping is now becoming a useful tool to study the large-scale structure of the universe through spatial variations in the integrated emission from galaxies and the intergalactic medium. We study intensity mapping of the Hα 6563Å, [OIII] 5007Å, [OII] 3727Å and Hβ 4861Å lines at 0.8 ≤ z ≤ 5.2. The mean intensities of these four emission lines are estimated using the observed luminosity functions (LFs), cosmological simulations, and the star formation rate density (SFRD) derived from observations at z . 5. We calculate the intensity power spectra and consider the foreground contamination of other lines at lower redshifts. We use the proposed NASA small explorer SPHEREx (the Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) as a case study for the detectability of the intensity power spectra of the four emission lines. We also investigate the cross correlation with the 21-cm line probed by CHIME (the Canadian Hydrogen Intensity Mapping Experiment), Tianlai experiment and SKA (the Square Kilometer Array) at 0.8 ≤ z ≤ 2.4. We find both the auto and cross power spectra can be well measured for the Hα, [OIII] and [OII] lines at z . 3, while it is more challenging for the Hβ line. Finally, we estimate the constraint on the SFRD from intensity mapping, and find we can reach accuracy higher than 7% at z . 4, which is better than usual measurements using the LFs of galaxies. Subject headings: cosmology: theory diffuse radiation intergalactic medium large-scale structure of universe