Cosmological Constraints on the Global Star Formation Law of Galaxies: Insights From Baryon Acoustic Oscillation Intensity Mapping

TL;DR

This paper proposes a novel cosmological method using baryon acoustic oscillation intensity mapping to study the global star formation law, enabling constraints on galaxy evolution models and cosmology.

Contribution

It introduces a new approach to probe the star formation law power index using large-scale LIM data and BAO bias effects, expanding astrophysical applications of LIM.

Findings

Future infrared surveys can constrain the star formation law index to 10-30% precision.

SPHEREx may marginally probe the star formation law index with its current survey.

Large LIM surveys can test galaxy evolution theories and cosmological models at high redshift.

Abstract

Originally proposed as a cosmological probe of the large-scale structure, line intensity mapping (LIM) also offers a unique window into the astrophysics of galaxy evolution. Adding to the astrophysical explorations of LIM technique that have traditionally focused on small, non-linear scales, we present a novel method to study the global star formation law using forthcoming data from large-scale baryonic acoustic oscillation (BAO) intensity mapping. Using the amplitude of the percent-level but scale-dependent bias induced by baryon fraction fluctuations on BAO scales, we show that combining auto- and cross-correlation power spectra of two (or more) LIM signals allows to probe the star formation law power index $\mathcal{N}$. We examine the prospect for mapping H$\alpha$ and [OIII] lines across all scales, especially where imprints of the baryon fraction deviation exist, with space missions like SPHEREx. We show that although SPHEREx may only marginally probe $\mathcal{N}$ by accessing a modest number of large-scale modes in its 200 deg$^2$ deep survey, future infrared all-sky surveys reaching a comparable depth with an improved spectral resolution ($R \gtrsim 400$) are likely to constrain $\mathcal{N}$ to a precision of 10$-$30%, sufficient for distinguishing models with varying feedback assumptions, out to $z\sim4$ using BAO intensity mapping. Leveraging this effect, large, cosmic-variance-limited LIM surveys in the far future can scrutinize the physical connection between galaxy evolution and the large-scale cosmological environment, while performing stringent tests of the standard cosmological model.