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Linking Galaxies to Their Neutral Gas Reservoir: A Roman–Rubin Synergy Survey of DLA Host Galaxies at Cosmic Noon
Program ID 19029
Science Category Intergalactic Medium
Program Type Analysis
Category Small
Principal Investigator Jiani Ding
PI Institution University of Arizona
Co-Investigators
  • Minghao Yue (University of Arizona)
  • Yongda Zhu (University of Arizona)
  • Xiaohui Fan (University of Arizona)
  • George Becker (University of California, Riverside)
  • Marie Wingyee Lau (University of California, Riverside)
  • Siwei Zou (Universidad de Chile)
  • Fuyan Bian (European Southern Observatory)
  • Weizhe Liu (University of Arizona)
Abstract Damped Lyman-alpha absorbers (DLAs) are the dominant reservoir of neutral gas and fuel the intense star formation activity at cosmic noon (z ~ 2-3). Simulations predict that galaxy properties strongly regulate the amount and distribution of surrounding neutral gas through processes like star-formation feedback and halo gas heating. However, the observational link between DLAs and their host galaxies remains poorly constrained because most DLAs lack identified hosts. To date, only ~70 DLA host galaxies have been identified, limiting our ability to test theoretical models of galaxy feedback and galaxy–gas coevolution. We propose to construct the largest, systematically selected sample of DLA host galaxies by combining deep imaging and grism spectroscopy from the Roman HLWAS with multi-band photometry from Rubin LSST. Using the first two years of Roman observations, we will study > 600 DLAs located within the HLWAS medium tier footprint. Accurate photometric redshifts from the joint Roman–Rubin dataset, together with Roman grism capacity and sharp PSF (PSF subtraction near quasar sightlines needed), will allow us to identify galaxies at the DLA redshift within impact parameters b less than 40 kpc. We expect to detect > 200 DLA host galaxies down to H ~ 25. This sample will enable the following experiments: 1. Measuring the stellar-mass distribution of DLA host galaxies. This will put strong constraints on the strength of star-formation feedback, and the critical galaxy mass dichotomizing cold-stream accretion from hot-halo, beyond which cold gas inflow is prohibited by shock heating. 2. Correlations between DLA properties (e.g. column density, impact parameter, metallicity) and host galaxy properties, including stellar mass, star-formation rate, morphology. With over 200 uniformly selected DLA host galaxies, this experiment will provide a statistically robust framework linking galaxies to their surrounding neutral gas reservoirs at the peak epoch of galaxy growth.