[CII] line intensity mapping the epoch of reionization with the Prime-Cam on FYST

TL;DR

This paper predicts the [CII] line intensity power spectrum during reionization, assesses its detectability with FYST, and explores how different galaxy formation models influence the results, aiming to constrain galaxy evolution at high redshift.

Contribution

It introduces a comprehensive simulation-based prediction of the [CII] intensity power spectrum for reionization studies and evaluates its detectability with the FYST telescope, highlighting the potential to constrain galaxy formation models.

Findings

The [CII] power spectrum amplitude varies by over a factor of 10 depending on model assumptions.

FYST can detect the [CII] power spectrum up to redshift 5.8, possibly up to 7.4.

The survey can measure clustering and shot noise scales, constraining galaxy formation relations.

Abstract

We predict the three-dimensional intensity power spectrum (PS) of the [CII] 158$\,\mu$m line throughout the epoch of (and post) reionization at redshifts from $\approx$ 3.5 to 8. We study the detectability of the PS in a line intensity mapping (LIM) survey with the Fred Young Submillimeter Telescope (FYST). We created mock [CII] tomographic scans in redshift bins at $z\approx$ 3.7, 4.3, 5.8, and 7.4 using the Illustris TNG300-1 $\Lambda$CDM simulation and adopting a relation between the star formation activity and the [CII] luminosity ($L_{[CII]}$) of galaxies. A star formation rate (SFR) was assigned to a dark matter halo in the Illustris simulation in two ways: (i) we adopted the SFR computed in the Illustris simulation and, (ii) we matched the abundance of the halos with the SFR traced by the observed dust-corrected ultraviolet luminosity function of high-redshift galaxies. The $L_{[CII]}$ is related to the SFR from a semi-analytic model of galaxy formation, from a hydrodynamical simulation of a high-redshift galaxy, or from a high-redshift [CII] galaxy survey. The [CII] intensity PS was computed from mock tomographic scans to assess its detectability with the anticipated observational capability of the FYST. The amplitude of the predicted [CII] intensity power spectrum varies by more than a factor of 10, depending on the choice of the halo-to-galaxy SFR and the SFR-to-$L_{[CII]}$ relations. In the planned $4^{\circ} \times 4^{\circ}$ FYST LIM survey, we expect a detection of the [CII] PS up to $z \approx$ 5.8, and potentially even up to $z \approx $ 7.4. The design of the envisioned FYST LIM survey enables a PS measurement not only in small (<10 Mpc) shot noise-dominated scales, but also in large (>50 Mpc) clustering-dominated scales making it the first LIM experiment that will place constraints on the SFR-to-$L_{[CII]}$ and the halo-to-galaxy SFR relations simultaneously.