The sizes of bright Lyman-break galaxies at with JWST PRIMER
arXiv:2401.15971
Abstract
We use data from the JWST Public Release IMaging for Extragalactic Research (PRIMER) survey to measure the size scaling relations of 1668 rest-frame UV-bright Lyman-break galaxies (LBGs) at with stellar masses . The sample was selected from seeing-dominated ground-based data, presenting an unbiased sampling of the morphology and size distributions of luminous sources. We fit Sérsic profiles to eight NIRCam bands and also measure a non-parametric half-light radius. We find that the size distributions with both measurements are well-fit by a log-normal distribution at all redshifts, consistent with disk formation models where size is governed by host dark-matter halo angular momentum. We find a size-redshift evolution of kpc, in agreement with JWST studies. When considering the typical (modal) size over , we find little evolution with bright LBGs remaining compact at kpc. Simultaneously, we find evidence for a build-up of large ( kpc) galaxies by . We find some evidence for a negatively sloped size-mass relation at when Sérsic profiles are used to fit the data in F200W. The intrinsic scatter in our size-mass relations increases at higher redshifts. Additionally, measurements probing the rest-UV (F200W) show larger intrinsic scatter than those probing the rest-optical (F356W). Finally, we leverage rest-UV and rest-optical photometry to show that disky galaxies are well established by , but are beginning to undergo dissipative processes, such as mergers, by . The agreement of our size-mass and size-luminosity relations with simulations provides tentative evidence for centrally concentrated star formation at high-redshift.
15 pages, 9 figures, 3 tables. Accepted to MNRAS. 2 figures added in appendix