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Arxiv: The Rise of Faint, Red AGN at z>4: A Sample of Little Red Dots in the JWST Extragalactic Legacy Fields Published: 4/4/2024 7:39:21 PM Updated: 1/20/2025 12:01:22 PM

Paper abstract: We present a sample of 341 "little red dots" (LRDs) spanning the redshiftrange z~2-11 using data from the CEERS, PRIMER, JADES, UNCOVER and NGDEEPsurveys. Unlike past use of color indices to identify LRDs, we employ continuumslope fitting using shifting bandpasses to sample the same rest-frame emissionblueward and redward of the Balmer break. This enables the detection of LRDsover a wider redshift range and with less contamination from galaxies withstrong breaks that otherwise lack a rising red continuum. The redshiftdistribution of our sample increases at z<8 and then undergoes a rapiddecline at z~4.5, which may tie the emergence of these sources to theinside-out growth that galaxies experience during this epoch. We find that LRDsare ~1 dex more numerous than X-ray and UV selected AGN at z~5-7. Withinour sample, we have identified the first two X-ray detected LRDs. An X-rayspectral analysis confirms that these AGN are moderately obscured with\log\,(N_{\rm H}/{\rm cm}^{2}) of 23.3^{+0.4}_{-1.3} and22.72^{+0.13}_{-0.16}. Our analysis reveals that reddened AGN emissiondominates their rest-optical light, while the rest-UV originates from theirhost galaxies. We also present NIRSpec observations from the RUBIES survey of17 LRDs that show broad emission lines consistent with AGN activity. Theconfirmed AGN fraction of our sample is 71\% for sources with F444W<26.5. Inaddition, we find three LRDs with blue-shifted Balmer absorption features intheir spectra, suggesting an outflow of high-density, low-ionization gas fromnear the central engine of these faint, red AGN.