The Rise of Faint, Red Active Galactic Nuclei at z > 4: A Sample of Little Red Dots in the JWST Extragalactic Legacy Fields

Authors

• Dale D. Kocevski, Colby College
• Steven L. Finkelstein, The University of Texas at Austin
• Guillermo Barro, University of the PacificFollow
• Anthony J. Taylor, The University of Texas at Austin
• Antonello Calabrò, Osservatorio Astronomico di Roma
• Brivael Laloux, Durham University
• Johannes Buchner, Max Planck Institute for Extraterrestrial Physics
• Jonathan R. Trump, University of Connecticut
• Gene C.K. Leung, The University of Texas at Austin
• Guang Yang, Kapteyn Instituut
• Mark Dickinson, NOIRLab
• Pablo G. Pérez-González, CSIC-INTA - Centro de Astrobiología (CAB)
• Fabio Pacucci, Harvard-Smithsonian Center for Astrophysics
• Kohei Inayoshi, Peking University
• Rachel S. Somerville, Simons Foundation
• Elizabeth J. McGrath, Colby College
• Hollis B. Akins, The University of Texas at Austin
• Micaela B. Bagley, The University of Texas at Austin
• Rebecca A.A. Bowler, The University of Manchester
• Laura Bisigello, Università degli Studi di Padova
• Adam Carnall, University of Edinburgh, Institute for Astronomy

Document Type

Article

Publication Title

Astrophysical Journal

Department

Physics

ISSN

15384357

Volume

986

Issue

2

DOI

10.3847/1538-4357/adbc7d

First Page

1

Last Page

30

Publication Date

6-11-2025

Abstract

We present a sample of 341 “little red dots” (LRDs) spanning the redshift range z ∼ 2-11 using data from the CEERS, PRIMER, JADES, UNCOVER, and NGDEEP surveys. Unlike past use of color indices to identify LRDs, we employ continuum slope fitting using shifting bandpasses to sample the same rest-frame emission blueward and redward of the Balmer break. This enables the detection of LRDs over a wider redshift range and with less contamination from galaxies with strong breaks that otherwise lack a rising red continuum. The redshift distribution of our sample increases at z < 8 and then undergoes a rapid decline at z ∼ 4.5, which may tie the emergence of these sources to the inside-out growth that galaxies experience during this epoch. We find that LRDs are ∼1 dex more numerous than X-ray- and UV-selected active galactic nuclei (AGN) at z ∼ 5-7. Within our sample, we have identified the first two X-ray-detected LRDs. An X-ray spectral analysis confirms that these AGN are moderately obscured with log ( N H / cm 2 ) of 23 . 3 − 1.3 + 0.4 and 22.7 2 − 0.16 + 0.13 . Our analysis reveals that reddened AGN emission dominates their rest-optical light, while the rest-UV originates from their host galaxies. We also present NIRSpec observations from the RUBIES survey of 17 LRDs that show broad emission lines consistent with AGN activity. The confirmed AGN fraction of our sample is 71% for sources with F444W < 26.5. In addition, we find three LRDs with blueshifted Balmer absorption features in their spectra, suggesting an outflow of high-density, low-ionization gas from near the central engine of these faint, red AGN.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Kocevski, Dale D.; Finkelstein, Steven L.; Barro, Guillermo; Taylor, Anthony J.; Calabrò, Antonello; Laloux, Brivael; Buchner, Johannes; Trump, Jonathan R.; Leung, Gene C.K.; Yang, Guang; Dickinson, Mark; Pérez-González, Pablo G.; Pacucci, Fabio; Inayoshi, Kohei; Somerville, Rachel S.; McGrath, Elizabeth J.; Akins, Hollis B.; Bagley, Micaela B.; Bowler, Rebecca A.A.; Bisigello, Laura; and Carnall, Adam, "The Rise of Faint, Red Active Galactic Nuclei at z > 4: A Sample of Little Red Dots in the JWST Extragalactic Legacy Fields" (2025). Pacific Faculty Work. 112.
https://scholarlycommons.pacific.edu/all-faculty/112