Taylor, AJ;
Kokorev, V;
Kocevski, DD;
Akins, HB;
Cullen, F;
Dickinson, M;
Finkelstein, SL;
... Zavala, JA; + view all
(2025)
CAPERS-LRD-z9: A Gas-enshrouded Little Red Dot Hosting a Broad-line Active Galactic Nucleus at z = 9.288.
Astrophysical Journal Letters
, 989
(1)
, Article L7. 10.3847/2041-8213/ade789.
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Abstract
We present CAPERS-LRD-z9, a little red dot (LRD) that we confirm to be a z = 9.288 broad-line active galactic nucleus (BLAGN). First identified as a high-redshift LRD candidate from PRIMER NIRCam photometry, follow-up NIRSpec/PRISM spectroscopy of CAPERS-LRD-z9 from the CANDELS-Area Prism Epoch of Reionization Survey (CAPERS) has revealed a broad 3500 km s<sup>−1</sup> full width at half-maximum Hβ emission line and narrow [O iii] λλ4959, 5007 lines, indicative of a BLAGN. Based on the broad Hβ line, we compute a canonical black hole mass of log ( M BH / M ⊙ ) = 7.58 ± 0.15 , although full consideration of systematic uncertainties yields a conservative range of 6.65 < log ( M BH / M ⊙ ) < 8.50 . These observations suggest that either a massive black hole seed or a lighter stellar remnant seed undergoing periods of super-Eddington accretion is necessary to grow such a massive black hole in ≲500 Myr of cosmic time. CAPERS-LRD-z9 exhibits a strong Balmer break, consistent with a central AGN surrounded by dense (∼10<sup>10</sup> cm<sup>−3</sup>) neutral gas. We model CAPERS-LRD-z9 using Cloudy to fit the emission redward of the Balmer break with a dense-gas-enshrouded AGN and bagpipes to fit the rest-ultraviolet emission as a host-galaxy stellar population. This upper limit on the stellar mass of the host galaxy (<10<sup>9</sup> M<inf>⊙</inf>) implies that the black hole to stellar mass ratio may be extremely large, possibly >5% (although systematic uncertainties on the black hole mass prevent strong conclusions). However, the shape of the UV continuum differs from typical high-redshift star-forming galaxies, indicating that this UV emission may also be of AGN origin; hence, the true stellar mass of the host may be still lower.
| Type: | Article |
|---|---|
| Title: | CAPERS-LRD-z9: A Gas-enshrouded Little Red Dot Hosting a Broad-line Active Galactic Nucleus at z = 9.288 |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/2041-8213/ade789 |
| Publisher version: | https://doi.org/10.3847/2041-8213/ade789 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons License. The images or other third-party material in this article are included in the Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | James Webb Space Telescope (2291); Active galactic nuclei (16); AGN host galaxies (2017); Supermassive black holes (1663) |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10212395 |
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