James Webb Space Telescope Feed Post

Are we surprised to find SMBHs with JWST at z > 9? Published: 5/21/2023 7:47:52 PM Updated: 5/21/2023 7:47:52 PM

Paper abstract: The recent discovery of new Active Galactic Nuclei (AGN) at z > 4 with JWST is revolutionising the black hole (BH) landscape at cosmic dawn, unveiling for the first time accreting BHs with masses of 10^6 - 10^7 Msun. To date, the most distant reside in CEERS-1019 at z=8.7 and GNz11 at z=10.6. Given the high rate of newly discovered high-z AGNs, more than 10 at z > 4, we wonder: are we really surprised to find them in the nuclei of z = 5 - 11 galaxies? Can we use the estimated properties to trace their origin? In this work, we predict the properties of 4 < z < 11 BHs and their host galaxies considering an Eddington-limited (EL) and a super-Eddington (SE) BH accretion scenario, using the Cosmic Archaeology Tool (CAT), a semi-analytical model for the formation and evolution of z > 4 AGNs and galaxies. We then calculate the transmitted spectral energy distribution of CAT synthetic candidates, representative of the estimated BH properties in CEERS-1019 and GNz11. We find that the estimated luminosity of high-z JWST detected AGNs are better reproduced by the SE model, where BHs descend from efficiently growing light and heavy seeds. Conversely, the host galaxy stellar masses are better matched in the EL model, in which all the systems detectable with JWST surveys JADES and CEERS appear to be descendants of heavy BH seeds. Our study suggests an evolutionary connection between systems similar to GNz11 at z=10.6 and CEERS-1019 at z=8.7 and supports the interpretation that the central point source of GNz11 could be powered by a super-Eddington (lambda_Edd = 2 - 3) accreting BH with mass 1.5 10^6 Msun, while CEERS-1019 harbours a more massive BH, with M_{BH} = 10^7 Msun, accreting sub-Eddington (lambda_Edd = 0.45 - 1), with a dominant emission from the host galaxy.