Heavy Seeds and the Multi-scale Fueling of Early Supermassive Black Holes and Little Red Dots
Abstract
The formation of supermassive black holes (SMBHs) in the early Universe has been a longstanding mystery due to the brief period available to assemble them. More recently, the unexpected discovery with the James Webb Space Telescope (JWST) of Little Red Dots (LRDs), compact sources exhibiting signatures of active galactic nuclei (AGN), has accentuated this challenge. Cosmological simulations investigating their formation and evolution confront the limitation that the compact scale of SMBH/LRD physics cannot be simultaneously resolved with the larger-scale cosmological environment. We address this limitation by utilizing a cutout technique, selecting a targeted region around an SMBH seed from a cosmological parent simulation and re-running the cutout at higher (sub-pc) resolution for shorter periods. We explore two SMBH formation scenarios: the standard, light seed stellar-remnant case, and the heavy-seed, direct collapse black hole (DCBH) channel. Within the high-resolution achieved by the cutouts, the DCBH, due to its larger mass, is able to induce a buildup of high density gas nearby and accrete gas in bursts of super-Eddington phases, growing in mass and producing an LRD-like spectrum. In contrast, the stellar remnant cannot do so and remains dormant, unable to affect the nearby gas or significantly evolve by gas accretion alone. Therefore, we find that observed high-redshift SMBHs and LRDs require the existence of heavy seeds to assemble dense gas around themselves, enabling efficient growth and producing red optical spectra with strong Balmer breaks resembling LRDs.
Related
- Overmassive No More: The Case for Little Red Dots Hosting Black Hole Seeds as Massive as Single Supermassive Stars
- Black Hole Seeds and Little Red Dots: Connecting Formation and Growth with a JWST Multi-Cycle Treasury Program
- From Dense Gas Clouds to Supermassive Black Hole Seeds: Hybrid Hydro/Direct N-body Simulations of Runaway Collision-driven Intermediate-mass Black Hole Formation
- Inflated Supermassive Stars as Little Red Dots and Progenitors of Supermassive Black Holes
- JWST's Little Red Dots as collapsed Supermassive Dark Stars
BibTeX
@misc{jeon2026heavy,
title = {{Heavy Seeds and the Multi-scale Fueling of Early Supermassive Black Holes and Little Red Dots}},
author = {Junehyoung Jeon and Volker Bromm and Boyuan Liu and Stella S. R. Offner and Anthony J. Taylor and Steven L. Finkelstein},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36089},
eprint = {2610.36089},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36089},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Heavy Seeds and the Multi-scale Fueling of Early Supermassive Black Holes and Little Red Dots
AU - Junehyoung Jeon
AU - Volker Bromm
AU - Boyuan Liu
AU - Stella S. R. Offner
AU - Anthony J. Taylor
AU - Steven L. Finkelstein
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.36089
UR - https://arxiv.org/abs/2610.36089
AB - The formation of supermassive black holes (SMBHs) in the early Universe has been a longstanding mystery due to the brief period available to assemble them. More recently, the unexpected discovery with the James Webb Space Telescope (JWST) of Little Red Dots (LRDs), compact sources exhibiting signatures of active galactic nuclei (AGN), has accentuated this challenge. Cosmological simulations investigating their formation and evolution confront the limitation that the compact scale of SMBH/LRD physics cannot be simultaneously resolved with the larger-scale cosmological environment. We address this limitation by utilizing a cutout technique, selecting a targeted region around an SMBH seed from a cosmological parent simulation and re-running the cutout at higher (sub-pc) resolution for shorter periods. We explore two SMBH formation scenarios: the standard, light seed stellar-remnant case, and the heavy-seed, direct collapse black hole (DCBH) channel. Within the high-resolution achieved by the cutouts, the DCBH, due to its larger mass, is able to induce a buildup of high density gas nearby and accrete gas in bursts of super-Eddington phases, growing in mass and producing an LRD-like spectrum. In contrast, the stellar remnant cannot do so and remains dormant, unable to affect the nearby gas or significantly evolve by gas accretion alone. Therefore, we find that observed high-redshift SMBHs and LRDs require the existence of heavy seeds to assemble dense gas around themselves, enabling efficient growth and producing red optical spectra with strong Balmer breaks resembling LRDs.
ER -