Super-Eddington accretion of black holes in early nuclear bursts gives birth to Little Red Dots

Yangyao Chen, Houjun Mo

First listed 2026-06-01 | Last updated 2026-05-29

Abstract

In a recent paper, Chen et al. developed a framework for modeling the seeding and growth of supermassive black holes (BHs) in the context of $Λ$CDM cosmogony. Here, we use a set of physically motivated criteria to select a population of predicted BHs and link them to Little Red Dots (LRDs) discovered by JWST. We show that the LRD population at high redshift ($z$) emerges naturally from a subset of BHs with super-Eddington accretion during nuclear bursts. The model suggests that the observed LRDs are the "tip of the iceberg" of a much larger population of less luminous BHs in the same subset. The model makes specific predictions for the LRD population, such as the mass distributions of their BHs and host galaxies/halos, and the piece-wise redshift evolution of their number density. The cosmological context of the model also allows us to link the observed LRD population to their progenitors (their BH seeds) and lower-$z$ descendant BHs, galaxies and halos. Most LRDs at $z\sim 5$ are seeded at $z \gtrsim 20$ through direct-collapse BHs or pair-instability supernovae from Pop-III stars, and have grown to $M_{\rm BH} \approx 10^5$--$10^7\,{\rm M}_\odot$ through nuclear bursts by their observed redshift. LRDs are predicted to have diverse descendants, ranging from compact dwarf galaxies to brightest cluster galaxies (BCGs) at $z=0$. These predictions are consistent with current observations and can be further tested. The success of this model indicates that the results presented here provide a robust foundation for building detailed models of the LRD population.

Short digest

Chen and Mo use their semi-analytic black-hole seeding and growth framework to identify a subset of model black holes undergoing super-Eddington accretion during nuclear bursts that naturally matches the observed Little Red Dot population. In this picture, the JWST LRDs are the visible tip of a much larger population of less luminous rapidly growing black holes, with predicted black-hole masses around 10^5-10^7 solar masses by z~5 and characteristic host-galaxy and halo mass distributions. The model also reproduces the observed piece-wise redshift evolution of LRD number density and links those objects back to mostly z>20 seeds formed through direct collapse or Pop III pair-instability channels. That broader cosmological bookkeeping matters because it connects LRDs to both their early-seeding origin and a wide descendant range by z=0, from compact dwarfs to brightest cluster galaxies.

Key figures to inspect

• Figure 1. Use this figure to show how the paper operationally defines the LRD population inside the model. The BH accretion-rate versus BH-mass plane and the BH-mass-fraction versus BH-mass plane make clear that the selected LRDs occupy the extreme tip of a burst-driven branch, which is the paper's key physical identification rather than a purely phenomenological fit.
• Figure 2. Use this figure for the paper's main population-level validation against observations. It demonstrates that the model reproduces the piece-wise redshift evolution of the LRD number density, while also showing how sensitive the prediction is to the burst-duration sampling and to alternative BH accretion-rate thresholds used in the selection.
• Figure 3. Use this full evolutionary synthesis figure because it carries the paper's strongest bottom-line claim. By following the selected z~5 LRDs from their seed channels at high redshift to their host-galaxy, halo, and black-hole properties at the observed epoch and then to their z=0 descendants, it turns the model from an LRD identification exercise into a concrete progenitor-and-descendant framework.