The Little Red Dots Are Direct Collapse Black Holes

TL;DR

This paper proposes that the observed 'Little Red Dots' in JWST data are naturally explained by emission from accreting Direct Collapse Black Holes, providing a unified model for their spectral features and evolution.

Contribution

The study introduces a radiation-hydrodynamic simulation model that reproduces the spectra and properties of LRDs as DCBHs without stellar contributions, linking observations to early Universe black hole formation.

Findings

LRD spectra are consistent with emission from accreting DCBHs.

The model explains weak X-ray emission and high-ionization lines.

LRDs are linked to pristine atomic-cooling halos and early black hole seeds.

Abstract

The discovery by JWST of a substantial population of compact "Little Red Dots" (LRDs) presents a major puzzle: their observed spectra defy standard astrophysical interpretations. Here, we show that LRD spectra are naturally reproduced by emission from an accreting Direct Collapse Black Hole (DCBH). Using radiation-hydrodynamic simulations, we follow the growth of the DCBH seed via a dense, compressionally heated, collisionally ionized accretion flow. The model self-consistently reproduces the screen responsible for the observed Balmer absorption, while allowing UV/optical emission to partially escape, along with reprocessed infrared radiation. Crucially, this structure is not a blackbody and requires no stellar contribution: the UV continuum originates entirely from reprocessed DCBH radiation, attenuated only by a small amount of dust with an extinction curve consistent with high-redshift galaxies. This single framework simultaneously explains the key observational puzzles of LRDs: (a) weak X-ray emission, (b) metal and high-ionization lines alongside absent star-formation features, (c) overmassive black holes, (d) compact morphology, (e) abundance and redshift evolution -- linking them directly to pristine atomic-cooling halos, (f) long-lived ($>100$ Myr), slowly variable phases driven by radiation pressure. Our findings indicate that JWST is witnessing the widespread formation of heavy black hole seeds in the early Universe.