A Little Red Dot at $\mathbf{z}=7.3$ within a Large Galaxy Overdensity

Abstract

The nature of "Little Red Dots" and their relation to other forms of accreting supermassive black holes remain an open question. Here we report the discovery of a Little Red Dot at $z=7.3$. It is attenuated by moderate amounts of dust, $A_V=2.79\text{mag}$, with an intrinsic bolometric luminosity of $10^{46.6}\text{erg}{\text{s}}^{-1}$ and a SMBH mass of $5\times 10^8{\text{M}}_{\odot }$. Most notably, this object is embedded in an overdensity of eight nearby galaxies, allowing us to calculate a spectroscopic estimate of the clustering of galaxies around Little Red Dots. We find a Little Red Dot-galaxy cross-correlation length of $r_0=8\pm 2{\text{h}}^{-1}\text{cMpc}$, comparable to that of $z\sim 6$ UV-luminous quasars. The resulting estimate of their minimum dark matter halo mass of ${\log }_{10}(M_{\text{halo, min}}/{\text{M}}_{\odot })=12.0_{-1.0}^{+0.8}$ indicates that nearly all halos above this mass must host actively accreting SMBHs at $z\approx 7$, in strong contrast with the far smaller duty cycle of luminous quasars ($<1\%$). Our results, taken at face value, motivate a picture in which SMBHs in Little Red Dot phases could serve as the obscured precursors of UV-luminous quasars, which provides a natural explanation for the short UV-luminous lifetimes inferred from both quasar clustering and quasar proximity zones.

The article is published in Nature Astronomy as Schindler, JT., Hennawi, J.F., Davies, F.B. et al. A little red dot at z = 7.3 within a large galaxy overdensity. Nat Astron (2025). https://doi.org/10.1038/s41550-025-02660-1

References in corpus (55)

• emcee: The MCMC Hammer
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results
• Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
• Composite Quasar Spectra From the Sloan Digital Sky Survey
• Cosmic-Ray Rejection by Laplacian Edge Detection
• A Catalog of Quasar Properties from SDSS DR7
• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• Estimating Black Hole Masses in Active Galaxies Using the Halpha Emission Line
• Inferring the star-formation histories of massive quiescent galaxies with BAGPIPES: Evidence for multiple quenching mechanisms
• The Assembly of the First Massive Black Holes
• An Empirical Ultraviolet Template for Iron Emission in Quasars as Derived from I Zw 1
• Determining Central Black Hole Masses in Distant Active Galaxies
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• The Radius-Luminosity Relationship for Active Galactic Nuclei: The Effect of Host-Galaxy Starlight on Luminosity Measurements
• Clustering of High Redshift ($z\ge 2.9$) Quasars from the Sloan Digital Sky Survey
• A Physical Model for the Origin of Quasar Lifetimes
• JADES. The diverse population of infant Black Holes at 4<z<11: merging, tiny, poor, but mighty
• Pōniuā'ena: A Luminous $z=7.5$ Quasar Hosting a 1.5 Billion Solar Mass Black Hole
• Quasar Clustering and the Lifetime of Quasars
• The Bolometric Quasar Luminosity Function at z = 0-7
• GA-NIFS: A massive black hole in a low-metallicity AGN at $z\sim 5.55$ revealed by JWST/NIRSpec IFS
• Binary Quasars in the Sloan Digital Sky Survey: Evidence for Excess Clustering on Small Scales
• What the Optical Recombination Lines Can Tell Us About the Broad Line Regions of Active Galactic Nuclei
• The clustering of intermediate redshift quasars as measured by the Baryon Oscillation Spectroscopic Survey
• Constraining the Lifetime of Quasars from their Spatial Clustering
• The JWST Extragalactic Mock Catalog: Modeling galaxy populations from the UV through the near-IR over thirteen billion years of cosmic history
• Clustering of intermediate redshift quasars using the final SDSS III-BOSS sample
• Nitrogen enhancements 440 Myr after the Big Bang: super-solar N/O, a tidal disruption event or a dense stellar cluster in GN-z11?
• Recalibration of the virial factor and M-sigma relation for local active galaxies
• The Bright End of the z~9 and z~10 UV Luminosity Functions using all five CANDELS Fields
• The performance of the blue prime focus Large Binocular Camera at the Large Binocular Telescope
• Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). VI. Black Hole Mass Measurements of Six Quasars at 6.1<z<6.7
• z~2-9 Galaxies Magnified by the Hubble Frontier Field Clusters II: Luminosity Functions and Constraints on a Faint-End Turnover
• JWST Noise Floor I: Random Error Sources in JWST NIRCam Time Series
• A dormant, overmassive black hole in the early Universe
• Evidence for Low Radiative Efficiency or Highly Obscured Growth of $z>7$ Quasars
• The Faint End of the Quasar Luminosity Function at $z\sim 5$ from the Subaru Hyper Suprime-Cam Survey
• A remarkable Ruby: Absorption in dense gas, rather than evolved stars, drives the extreme Balmer break of a Little Red Dot at $z=3.5$
• Quasar Luminosity Function at z = 7
• ALMA Confirmation of an Obscured Hyperluminous Radio-Loud AGN at $z=6.853$ Associated with a Dusty Starburst in the 1.5 deg${}^2$ COSMOS Field
• Chronicling the reionization history at $6\lesssim z\lesssim 7$ with emergent quasar damping wings
• TheHaloMod: An online calculator for the halo model
• A Sample of Quasars with Strong Nitrogen Emission Lines from the Sloan Digital Sky Survey
• Strong Clustering of Lyman Break Galaxies around Luminous Quasars at z~4
• The need for obscured supermassive black hole growth to explain quasar proximity zones in the epoch of reionization
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope V. Optimal algorithms for planning multi-object spectroscopic observations
• "Little red dots" cannot reside in the same dark matter halos as comparably luminous unobscured quasars
• A unified model for the clustering of quasars and galaxies at $z\approx 6$
• Mapping quasar light echoes in 3D with Lyα forest tomography
• Measuring the Density Fields around Bright Quasars at $z\sim 6$ with XQR-30 Spectra
• JWST ERS Program Q3D: The pitfalls of virial BH mass constraints shown in a z = 3 quasar with an ultramassive host
• Revisiting the Extreme Clustering of $z\approx 4$ Quasars with Large Volume Cosmological Simulations
• A Big Red Dot: Scattered light, host galaxy signatures and multi-phase gas flows in a luminous, heavily reddened quasar at cosmic noon
• The Soltan argument at $z=6$: UV-luminous quasars contribute less than 10% to early black hole mass growth

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• Connecting the Dots: UV-Bright Companions of Little Red Dots as Lyman-Werner Sources Enabling Direct Collapse Black Hole Formation
• A first look at quasar-galaxy clustering at $z\simeq 7.3$
• Euclid: Discovery of 31 new quasars at $6.6<z<7.8$
• Back to basics: Little Red Dots as galaxies and dust-obscured AGNs in a synthetic NIRCam sky simulated with L-GalaxiesBH
• The rise and fall of Little Red Dots could be driven by the environment