Discovery and properties of ultra-high redshift galaxies (9 < z < 12) in the JWST ERO SMACS 0723 Field

• DOI: 10.1093/mnras/stac3347
• Publication Date: 2022-11-18T15:26:15Z
• Authors: N J Adams; C J Conselice; L Ferreira; D Austin; J A A Trussler; I Juodžbalis; S M Wilkins; J Caruana; P Dayal; A Verma; A P Vijayan
• Keywords: Stellar mass

We present a reduction and analysis of the \textit{James Webb Space Telescope} (JWST) SMACS~0723 field using new post-launch calibrations to conduct search for ultra-high-redshift galaxies ($z > 9$) within Epoch Reionisation. this by modelling photometric redshifts in several ways all sources applying conservative magnitude cuts ($m_{\rm F200W} < 28$) identify strong Lyman breaks greater than 1 magnitude. find four $z 9$ candidate which have not previously been identified, with one object at = 11.5$, another is possibly close pair galaxies. measure from other studies recovery rate be only 23 per cent, many being assigned lower redshift, dusty solutions our work. Most sample show evidence Balmer-breaks, or extreme emission lines H$\beta$ [OIII], demonstrating that stellar populations could advanced age very young depending on cause F444W excess. discuss resolved structures these early S\'{e}rsic indices reveal mixture light concentration levels, but sizes systems are exceptionally small ($< 0.5$~kpc). These masses M$_{*} \sim 10^{9.0}$ M$_{\odot}$, 11.5$ dwarf galaxy mass 10^{7.8}$ -- $10^{8.2}$ M$_{\odot}$. ultra high-redshift excellent targets future NIRSpec observations aimed better understand their physical nature.