Little Red Dots are Direct-collapse Black Hole–forming Galaxies
5 affiliations
- 1Portsmouth University
- 2United Arab Emirates University
- 3Aristotle University of Thessaloniki
- 4University of Edinburgh
- 5Center for Astrophysics
Abstract
“Little red dots” (LRDs) at 4 < z < 8 are one of the most challenging discoveries by JWST to date because their distinctive V-shaped spectra and compact morphologies defy conventional astrophysical interpretation. Previous attempts to explain LRDs as compact stellar systems, heavily cocooned black holes (BHs) with differential flows, supermassive stars, or more exotic objects like “black hole stars” cannot either show how they formed, explain the origin of the dense shells needed for the absorption features in their spectra, or account for their observed abundances or inferred lifetimes. Here we show that LRDs are simply direct-collapse BH galaxies in which the BH is still shrouded by the massive disk that created it. Our cosmological simulations yield spectra that are good matches to those of LRDs because high densities at the center of the disk trap X-rays from the BH and produce the observed Balmer absorption features while allowing UV, optical, and reprocessed IR flux to partly escape. The host galaxy forms a dense 10 ⁸ M ⊙ cluster of stars with a radius of 150 pc next to the BH, consistent with observations of LRDs. Our models reproduce a wide variety of LRD spectra, from typical objects like RUBIES-EGS-42046 at z = 5.28 to those with the strongest Balmer breaks such as MoM-BH * −1 at z = 7.76 and those at the highest redshifts like CAPERS-LRD-z9 at z = 9.29.
Related
- Ultraviolet diversity of Little Red Dots as a probe for direct-collapse black hole ages
- Ultraviolet diversity of Little Red Dots as a probe for direct-collapse black hole ages
- Between Little Red Dots and Star-Forming Galaxies: A Sequence in the Optical Continuum Slope
- Formation of Heavy Seed Black Holes and Little Red Dots-like Compact Clusters in Metal-enriched Star-forming Regions
- More Numerous and Bluer: Companions of the Brightest Little Red Dots Differ from Control Galaxies at >3σ, Hinting at Synchronized Black Hole Seed Formation
BibTeX
@article{whalen2026little,
title = {{Little Red Dots are Direct-collapse Black Hole–forming Galaxies}},
author = {Daniel J. Whalen and Muhammad A. Latif and Konstantinos Topalakis and Fergus Cullen and Devesh Nandal and Sadegh Khochfar},
journal = {The Astrophysical Journal Letters},
year = {2026},
month = oct,
doi = {10.3847/2041-8213/aeb37a},
url = {https://iopscience.iop.org/article/10.3847/2041-8213/aeb37a},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Little Red Dots are Direct-collapse Black Hole–forming Galaxies
AU - Daniel J. Whalen
AU - Muhammad A. Latif
AU - Konstantinos Topalakis
AU - Fergus Cullen
AU - Devesh Nandal
AU - Sadegh Khochfar
PY - 2026
DA - 2026/10/29
JO - The Astrophysical Journal Letters
DO - 10.3847/2041-8213/aeb37a
UR - https://iopscience.iop.org/article/10.3847/2041-8213/aeb37a
AB - “Little red dots” (LRDs) at 4 < z < 8 are one of the most challenging discoveries by JWST to date because their distinctive V-shaped spectra and compact morphologies defy conventional astrophysical interpretation. Previous attempts to explain LRDs as compact stellar systems, heavily cocooned black holes (BHs) with differential flows, supermassive stars, or more exotic objects like “black hole stars” cannot either show how they formed, explain the origin of the dense shells needed for the absorption features in their spectra, or account for their observed abundances or inferred lifetimes. Here we show that LRDs are simply direct-collapse BH galaxies in which the BH is still shrouded by the massive disk that created it. Our cosmological simulations yield spectra that are good matches to those of LRDs because high densities at the center of the disk trap X-rays from the BH and produce the observed Balmer absorption features while allowing UV, optical, and reprocessed IR flux to partly escape. The host galaxy forms a dense 10 ⁸ M ⊙ cluster of stars with a radius of 150 pc next to the BH, consistent with observations of LRDs. Our models reproduce a wide variety of LRD spectra, from typical objects like RUBIES-EGS-42046 at z = 5.28 to those with the strongest Balmer breaks such as MoM-BH * −1 at z = 7.76 and those at the highest redshifts like CAPERS-LRD-z9 at z = 9.29.
SN - 2041-8213
SN - 2041-8205
ER -