Extreme properties of a compact and massive accreting black hole host in the first 500 Myr.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41257816.
- Also identified by DOI 10.1038/s41467-025-65070-x and PMC identifier 12630725.
- Licence recorded as CC BY-NC-ND.
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Abstract
Little red dots (LRDs) are a high redshift galaxy population. Despite their high number densities, their nature is still uncertain. Here we present CANUCS-LRD-z8.6, a spectroscopically confirmed little red dot at a spectroscopic redshift of z<sub>spec</sub> = 8.6319, hosting an active galactic nucleus. Its spectrum exhibits broad Hβλ4863 Å emission, high-ionization lines (C iv, N iv]), high electron temperature, which are indicative of active galactic nucleus activity, and low metallicity (Z < 0.1-0.2Z<sub>⊙</sub>). The inferred black hole mass, <math xmlns="http://www.w3.org/1998/Math/MathML"> <msub><mrow><mi>M</mi></mrow> <mrow><mi>BH</mi></mrow> </msub> <mo>=</mo> <mn>1</mn> <mo>.</mo> <msubsup><mrow><mn>0</mn></mrow> <mrow><mo>-</mo> <mn>0.4</mn></mrow> <mrow><mo>+</mo> <mn>0.6</mn></mrow> </msubsup> <mo>×</mo> <mn>1</mn> <msup><mrow><mn>0</mn></mrow> <mrow><mn>8</mn></mrow> </msup> <mspace></mspace> <msub><mrow><mi>M</mi></mrow> <mrow><mo>⊙</mo></mrow> </msub> </math> , poses strong constraints on current black hole formation models and simulations. Additionally, its black hole is over-massive relative to its host, deviating from local M<sub>BH</sub> - M<sub>*</sub> relations, suggesting an early, rapid black hole growth preceding that of its galaxy. CANUCS-LRD-z8.6 may represent an evolutionary link between early massive black holes and the luminous quasars observed at z = 6.