Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys

  • Matthee J
  • Naidu R
  • Brammer G
  • et al.
78Citations
Citations of this article
57Readers
Mendeley users who have this article in their library.

Abstract

Characterizing the prevalence and properties of faint active galactic nuclei (AGNs) in the early Universe is key for understanding the formation of supermassive black holes (SMBHs) and determining their role in cosmic reionization. We perform a spectroscopic search for broad H α emitters at z ≈ 4–6 using deep JWST/NIRCam imaging and wide field slitless spectroscopy from the EIGER and FRESCO surveys. We identify 20 H α lines at z = 4.2–5.5 that have broad components with line widths from ∼1200–3700 km s −1 , contributing ∼30%–90% of the total line flux. We interpret these broad components as being powered by accretion onto SMBHs with implied masses ∼10 7–8 M ⊙ . In the UV luminosity range M UV,AGN+host = −21 to −18, we measure number densities of ≈10 −5 cMpc −3 . This is an order of magnitude higher than expected from extrapolating quasar UV luminosity functions (LFs). Yet, such AGN are found in only <1% of star-forming galaxies at z ∼ 5. The number density discrepancy is much lower when compared to the broad H α LF. The SMBH mass function agrees with large cosmological simulations. In two objects, we detect complex H α profiles that we tentatively interpret as caused by absorption signatures from dense gas fueling SMBH growth and outflows. We may be witnessing early AGN feedback that will clear dust-free pathways through which more massive blue quasars are seen. We uncover a strong correlation between reddening and the fraction of total galaxy luminosity arising from faint AGN. This implies that early SMBH growth is highly obscured and that faint AGN are only minor contributors to cosmic reionization.

Cite

CITATION STYLE

APA

Matthee, J., Naidu, R. P., Brammer, G., Chisholm, J., Eilers, A.-C., Goulding, A., … Yue, M. (2024). Little Red Dots: An Abundant Population of Faint Active Galactic Nuclei at z ∼ 5 Revealed by the EIGER and FRESCO JWST Surveys. The Astrophysical Journal, 963(2), 129. https://doi.org/10.3847/1538-4357/ad2345

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free