UC Riverside

Spectroscopic and photometric intensity mapping are emerging techniques for ob- serving large cosmological volumes with a high frequency but low spatial resolution survey. We apply this technique to study large scale structure as both a tool for inference and for constraining theories of gravity. In particular, we make forecasts for the performance of future all-sky UV experiments with a technique that extracts the redshift distribution of UV-optical background photon emission. We consider the Cosmological Advanced Survey Telescope for Optical-UV Research (CASTOR) and the Spectro-Photometer for the His- tory of the Universe, Epoch of Reionization, and Ices Explorer (SPHEREx). We show that under reasonable error models, CASTOR measures the UV background SED 2-10 times better than existing data.

We then study the detectability of deviations from General Relativity through mm-wave spectroscopic line intensity mapping of galaxies that trace large scale structure. We specifically consider measurements of the matter power spectrum and redshift space distortion multipole moments including the effects of foregrounds and emission from interloping lines. In the context of Horndeski theories, we calculate the sensitivity that future experiments would need in order to produce constraints on linear theory parameters that are comparable to or better than the best existing constraints from galaxy surveys and the Cosmic Microwave Background.