A Roman Benchmark Study of the HI Gas and Galaxy Relation Across Cosmic-Noon Protoclusters and Filaments
| Program ID | 19025 |
|---|---|
| Science Category | Large Scale Structure of the Universe |
| Program Type | Analysis |
| Category | Small |
| Principal Investigator | Kazuki Daikuhara |
| PI Institution | Japan Aerospace Exploration Agency |
| Co-Investigators |
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| Abstract | Protoclusters at cosmic noon are key laboratories for understanding how galaxy growth is regulated by large-scale structure, gas accretion, and environmental processing. We propose a benchmark study of galaxy environments at z~2 by combining the Roman High Latitude Wide Area Survey in the COSMOS deep field with the three-dimensional HI tomography from the CLAMATO survey. This unique dataset enables a homogeneous, wide-field view of protocluster cores, outskirts, and surrounding filaments as a single connected system, overcoming the small field of view and heterogeneous target selections that have limited previous studies. Using Roman imaging and grism spectroscopy, we will derive secure redshifts, stellar populations, morphologies, AGN, and gas-phase metallicities for galaxies across the CLAMATO volume. By linking these measurements to the diffuse HI distribution, we will quantify how star formation, black hole growth, structural transformation, quenching, and chemical enrichment depend on both the global environment and local gas overdensity. In particular, we will test whether these processes are first triggered in HI-rich filaments and outskirts or only in the densest protocluster cores, and whether weak HI absorption can trace feedback-heated gas around AGN-hosting structures. This program will establish the first uniform Roman-era benchmark for the gas–galaxy connection in the rapid assembly of large-scale structures at cosmic noon. |