GN-z11: The environment of an active galactic nucleus at<i>z</i> = 10.603
Jan Scholtz, Callum Witten, Nicolas Laporte, Hannah Übler, Michele Perna, R. Maiolino, Santiago Arribas, William Baker, Jake S. Bennett, Francesco D’Eugenio, Charlotte Simmonds, Sandro Tacchella, Joris Witstok, Andrew J. Bunker, Stefano Carniani, S. Charlot, G. Cresci, Emma Curtis-Lake, Daniel J. Eisenstein, Nimisha Kumari, Brant Robertson, Bruno Rodríguez Del Pino, Renske Smit, Giacomo Venturi, Christina C. Williams, Christopher N. A. Willmer
Abstract
Recent observations with the James Webb Space Telescope (JWST) have further refined the spectroscopic redshift of GN-z11, one of the most distant galaxies identified with the Hubble Space Telescope, at z = 10.603. The presence of extremely dense gas (> 10 10 cm −3 ), the detection of high-ionisation lines and of CII*1335 emission, and the presence of an ionisation cone indicate that GN-z11 also hosts an active galactic nucleus. Further photometric and spectroscopic follow-up demonstrates that it lies in a large-scale, overdense structure with possible signatures of Population III stars in its halo. Surprisingly, Ly α has also been detected despite the expected largely neutral intergalactic medium at such a redshift. We exploit recent JWST/NIRSpec integral field unit observations to demonstrate that the Ly α emission in GN-z11 is part of an extended halo with a minimum size of 0.8–3.2 kpc, depending on the definition used to derive the halo size. The surface brightness of the Ly α halo around GN-z11 appears consistent with Ly α halos observed around z ∼ 6 quasars. At the wavelength of Ly α at z ∼ 10.6, we identify three other emission line candidates within the integral field unit field of view with no UV rest-frame counterpart visible in deep images from the JWST/NIRCam. If confirmed, this could be the first evidence that the local region of GN-z11 represents a candidate protocluster core, forming just 400 Myr after the Big Bang. We give a first estimate of the dark matter halo mass of this structure ( M h = 2.96 −0.39 +0.44 × 10 10 M ⊙ ), which is consistent with a Coma-like cluster progenitor.