Accelerated Structural Evolution of Galaxies in a Starbursting Cluster at z = 2.51

Abstract

Structural properties of cluster galaxies during their peak formation epoch, z ∼ 2–4 provide key information on whether and how the environment affects galaxy formation and evolution. Based on deep Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) imaging toward the z = 2.51 cluster, J1001, we explore environmental effects on the structure, color gradients, and stellar populations of a statistical sample of cluster star-forming galaxies (SFGs). We find that the cluster SFGs are on average smaller than their field counterparts. This difference is most pronounced at the high-mass end (M ⋆ > 1010.5 M ⊙), with nearly all of them lying below the mass–size relation of field galaxies. The high-mass cluster SFGs are also generally old, with a steep negative color gradient, indicating an early formation time likely associated with strong dissipative collapse. For low-mass cluster SFGs, we unveil a population of compact galaxies with steep positive color gradients that are not seen in the field. This suggests that the low-mass compact cluster SFGs may have already experienced strong environmental effects, e.g., tidal/ram pressure stripping, in this young cluster. These results provide evidence on the environmental effects at work in the earliest formed clusters with different roles in the formation of low- and high-mass galaxies.

JWST’s First Glimpse of a z > 2 Forming Cluster Reveals a Top-heavy Stellar Mass Function

“…Then, we perform additional subtraction of the stripe-like 1/f noises (e.g., Bagley et al 2023), background structure, and some remaining cosmic rays (e.g., Rieke et al 2023) for each "cal" file output by stage 2. During stage 3, we use a reference catalog based on previous HST/Wide Field Camera 3 (WFC3 F160W image (Xu et al 2023) for astrometry calibration.…”

“…The deep HST/WFC3 F125W and F160W images of J1001 have been obtained during Project 14750 (PI: T. Wang) with details shown in Xu et al (2023). These mosaics from HST have been resampled to match the pixel size of JWST/NIRCam images with Montage (Berriman et al 2003;Good & Berriman 2019).…”

“…In this Letter, we combine the deep-and high-resolution images from JWST/NIRCam, narrowband imaging from Subaru/MOIRCS, and CO spectroscopy from the Atacama Large Millimeter/submillimeter Array (ALMA)/NOEMA/ Very Large Array (VLA) to provide a complete census of member galaxies in the z spec = 2.51 cluster CLJ1001 (hereafter, J1001; Wang et al 2016). Previous studies of J1001 have found that it has enhanced star formation rate (SFR), short gas depletion time, and strong evidence that the properties of member galaxies are affected by the extreme environment (Wang et al 2016(Wang et al , 2018Gómez-Guijarro et al 2019;Xiao et al 2022;Xu et al 2023). Here we further show a population of Hubble Space Telescope (HST)-undetected red member galaxies with bluer companions, which shows that even at z ∼ 2.5, the high-resolution NIR-to-mid-infrared images from JWST are necessary to uncover the complete massive galaxy population of (proto)clusters.…”