Bridging the Missing Link: Little Red Dots at z~0.5–2 with Roman HLWAS
| Program ID | 19033 |
|---|---|
| Science Category | Active Galaxies & Supermassive Black Holes |
| Program Type | Analysis |
| Category | Medium |
| Principal Investigator | Yichen Liu |
| PI Institution | University of Arizona, Steward Observatory |
| Co-Investigators |
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| Abstract | Little Red Dots (LRDs) represent a newly identified population of compact, red, AGN-like sources in the high-redshift universe. Their characteristic V-shaped spectral energy distributions (SEDs) challenge conventional models of black hole (BH) accretion and early galaxy assembly. Although JWST deep fields have revealed a rapidly growing sample of LRDs at z>4, and local LRDs have recently been reported at z~0.1, there remains a critical gap at intermediate redshifts. The absence of a statistically significant sample at z~0.5–2, covering over 5 Gyrs in cosmic time, prevents a systematic study of how LRDs evolve across cosmic time. We propose a data analysis program using the Roman High-Latitude Wide-Area Survey (HLWAS) to identify LRDs at z~0.5–2, primarily within the Deep tier. The depth and near-infrared wavelength coverage of the Deep tier enable robust selection of compact, red nuclei across a broad redshift range, capturing rest-frame optical features that are critical for identifying LRD-like SED shapes. The deep grism spectroscopy will provide secure redshifts and precise measurements of H-alpha and other strong emission lines, enabling physical discrimination from obscured AGN and extreme star-forming systems. We will also develop efficient LRD selection in HLWAS Medium tier, which will provide large statistical samples in the bright end that connect LRDs with luminous quasars and large scale structure. This program will establish the first statistically meaningful sample of medium-redshift LRDs, bridging the gap between high-redshift LRDs and their local counterparts. By constructing a continuous evolutionary sequence, we will constrain BH growth modes, accretion geometries, and host galaxy properties in compact AGN systems. The resulting catalog will provide a calibrated empirical framework for interpreting faint, compact AGN across cosmic time. |