Abstract
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
H-alpha6563A, OIII5007A, OII3727A and H-beta4861A 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 four lines at z<3, especially for the H-alpha, OIII and OII lines.
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.
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