Where Do Little Red Dots Go After Cosmic Dawn? A Wide-Area Roman Census at Cosmic Noon
| Program ID | 19062 |
|---|---|
| Science Category | Active Galaxies & Supermassive Black Holes |
| Program Type | Analysis |
| Category | Medium |
| Principal Investigator | Vasily Kokorev |
| PI Institution | University of Texas, Austin |
| Co-Investigators |
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| Abstract | Little Red Dots (LRDs) are one of the most surprising discoveries of JWST, revealing a population of compact, luminous sources at high redshift whose physical nature remains uncertain. If LRDs trace an early phase of rapid black hole growth, their abundance should decline sharply toward lower redshift; if they instead arise from compact stellar systems, their number density may remain flat or even increase toward cosmic noon. Constraining their evolution therefore provides a direct and decisive test of their origin. However, the LRD population at below z=4 remains essentially unconstrained. JWST surveys probe extremely small areas, while existing wide-field searches are both too shallow and too low-resolution to reliably isolate compact LRD nuclei, leading to highly uncertain and conflicting measurements. We propose to use the Roman High Latitude Wide Area Survey, combined with LSST photometry, to conduct the first robust census of LRDs over z= 0.7 - 2.5 across ~2400 deg2. Roman uniquely combines sufficient depth to overlap with the luminosity regime probed by JWST with the angular resolution required to separate compact nuclear sources from extended galaxy light. This dataset will enable three key measurements: the first statistically robust LRD luminosity function at below z=3, a wide-area census of broad Balmer emission as a direct AGN diagnostic, and a variability analysis to identify accreting black holes. Together, these measurements will determine whether LRDs represent the early growth phase of supermassive black holes, the formation of compact stellar systems, or a population that disappears entirely after cosmic dawn. |