Constraining the Nearby Y-dwarf Population with Roman HLWAS
| Program ID | 19010 |
|---|---|
| Science Category | Stellar Populations |
| Program Type | Analysis |
| Category | Small |
| Principal Investigator | Shota Miyazaki |
| PI Institution | Institute of Space and Astronautical Science |
| Co-Investigators |
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| Abstract | This program uses the first public data from the Roman High-Latitude Wide Area Survey (HLWAS) to identify the coldest nearby brown dwarfs. The aim is to determine whether HLWAS can provide a well-defined sample of Y dwarfs suitable for measuring their luminosity function and space density in the solar neighborhood. The population of such extremely cold objects remains poorly constrained, yet it provides key empirical input for models of brown-dwarf cooling and for interpreting the atmospheres of old giant exoplanets. We begin by scanning the prompt VISIT L4 catalogs to locate extremely red candidates across the HLWAS footprint. For each candidate, photometry and positions will be remeasured directly on Roman image cutouts. Objects inconsistent with nearby Y dwarfs will be rejected using shorter-wavelength non-detections, external infrared data, and proper-motion constraints that distinguish nearby sources from stationary extragalactic contaminants. To characterize the survey selection, we will perform catalog-audit searches and injection–recovery tests across fields with different depths, background levels, and crowding. The program will produce a Roman-defined sample of Y-dwarf candidates together with the completeness and contamination estimates required for population analysis. From this sample, we will derive constraints on the nearby Y-dwarf luminosity function and space density. The photometry and astrometry pipeline developed for this work will also be released as open-source software for use in other HLWAS analyses and related near-infrared survey data. |