Spider-Webb: Spatially-Resolved Evidence of Inside-Out Quenching in the Spiderweb Protocluster at $z \sim 2$

TL;DR

This study investigates how quenching operates in a dense high-redshift environment by performing pixel-by-pixel SED fitting on JWST and HST data for the Spiderweb protocluster at $z \sim 2.16$. It yields spatial maps of stellar mass, star-formation rate, specific star-formation rate, and UVJ colors, revealing mass-dependent inside-out quenching in quiescent galaxies with $\log(M_*/M_{\odot}) \ge 10.5$ and central sSFR suppressed by about $1$ dex relative to outer regions, as well as a link between central star formation and Sérsic index. The results support AGN-driven feedback as a plausible quenching mechanism by $z \sim 2$ and show heterogeneous internal star formation, highlighting the role of morphology and environment in early quenching. Overall, the work provides rigorous spatially-resolved constraints on galaxy evolution during the peak era of cosmic star formation and demonstrates the power of JWST+HST data for protocluster studies.

Abstract

We present a spatially-resolved analysis of galaxy quenching within the Spiderweb Protocluster at $z \sim 2.16$, combining deep imaging from the James Webb Space Telescope (JWST) and the Hubble Space Telescope (HST). Utilizing pixel-by-pixel spectral energy distribution fitting, we derive maps of stellar mass, star formation rate (SFR), specific SFR (sSFR), and rest-frame UVJ colors. Quiescent galaxies, predominantly found at $\log(M_*/M_{\odot}) \geq 10.5$, exhibit clear mass-dependent inside-out quenching, with central sSFR approximately an order of magnitude lower than outer regions, while lower-mass star-forming galaxies show flat sSFR profiles. Central star formation activity fundamentally anti-correlates with Sérsic index, indicating reduced activity in bulge-dominated systems. Spatially resolved UVJ colors reveal heterogeneous internal star formation, distinguishing star-forming regions in quiescent hosts from those in globally star-forming systems. These findings demonstrate that quenching mechanisms were effectively operating by $z \sim 2$, with the observed inside-out patterns and morphological correlations consistent with AGN-driven feedback processes. Our study provides key observational constraints on galaxy evolution during this critical epoch.