Roman-Cosmic Noon: A Legacy Spectroscopic Survey of Massive Field and Protocluster Galaxies at $2<z<3$

TL;DR

The Roman-Cosmic Noon survey aims to provide an unprecedented, large-scale spectroscopic dataset of protocluster galaxies at redshifts 2 to 3, enabling detailed studies of galaxy evolution in dense environments.

Contribution

It introduces a comprehensive, deep, wide-area spectroscopic survey targeting 1500 protoclusters and 15,000 galaxies at $2<z<3$, filling a gap in current data and enabling new insights.

Findings

Will measure stellar mass functions and quenched fractions.

Will analyze galaxy morphologies and stellar ages.

Will provide extensive legacy data for galaxy evolution studies.

Abstract

Protoclusters are the densest regions in the distant universe ($z>2$) and are the progenitors of massive galaxy clusters ($M_{halo}>10^{14}{\rm M}_\odot$) in the local universe. They undoubtedly play a key role in early massive galaxy evolution and they may host the earliest sites of galaxy quenching or even induce extreme states of star formation. Studying protoclusters therefore not only gives us a window into distant galaxy formation but also provides an important link in our understanding of how dense structures grow over time and modify the galaxies within them. Current protocluster samples are completely unable to address these points because they are small and selected in a heterogeneous way. We propose the Roman-Cosmic Noon survey, whose centerpiece is an extremely deep (30ksec) and wide area (10 deg$^2$) prism slitless spectroscopy survey to identify the full range of galaxy structures at $2<z<3$. This survey will include 1500 uniformly selected protoclusters, their surrounding cosmic web environments, and at least 15,000 protocluster galaxies with $M_\star>10^{10.5} {\rm M}_\odot$ across the full range of star formation histories as well as many more lower mass star-forming galaxies. The survey will also contain field galaxies to much lower masses than in the High Latitude Wide Area Survey, but over an area dwarfing any current or planned deep spectroscopy probe at $z>2$. With the prism spectroscopy and some modest additional imaging this survey will measure precise stellar mass functions, quenched fractions, galaxy and protocluster morphologies, stellar ages, emission-line based SFRs, and metallicities. It will have extensive legacy value well beyond the key protocluster science goals.