Cosmological Constraints from Line Intensity Mapping with Interlopers

Abstract

Understanding the formation and evolution of the universe is crucial for cosmological studies, and line intensity mapping provides a powerful tool for this kind of study. We propose to make use of multipole moments of a redshift-space line intensity power spectrum to constrain the cosmological and astrophysical parameters, such as the equation of state of dark energy, massive neutrinos, primordial non-Gaussianity, and star formation rate density. As an example, we generate mock data of multipole power spectra for H α 6563 Å, [O iii ] 5007 Å, and [O ii ] 3727 Å measured by the SPHEREx experiment at z  = 1 considering contaminations from interloper lines, and use the Markov Chain Monte Carlo method to constrain the parameters in the model. We find a good fitting result of the parameters compared to their fiducial values, which means that the multipole power spectrum can effectively distinguish signal and interloper lines, and break the degeneracies between parameters, such as line mean intensity and bias. We also explore the cross-power spectrum with the Chinese Space Station Telescope spectroscopic galaxy survey in the constraints. Since more accurate fitting results can be obtained by including measurements of the emission lines at higher redshifts out to at least z  = 3, and cross-correlations between emission lines can be involved, line intensity mapping is expected to offer excellent results in future cosmological and astrophysical studies.