The Stellar Mass Function in CANDELS and Frontier Fields: The Buildup of Low-mass Passive Galaxies since z ∼ 3

Abstract

Despite significant efforts in recent years, the physical processes responsible for the formation of passive galaxies through cosmic time remain unclear. The shape and evolution of the stellar mass function (SMF) give an insight into these mechanisms. Taking advantage of the CANDELS and the deep Hubble Frontier Fields (HFF) programs, we estimated the SMF of total, star-forming, and passive galaxies from z = 0.25 to z = 2.75 to unprecedented depth and we focus on the latter population. The density of passive galaxies underwent a significant evolution over the last 11 Gyr. They account for 60% of the total mass in the nearby universe against ∼20% observed at z ∼ 2.5. The inclusion of the HFF program allows us to detect, for the first time at z > 1.5, the characteristic upturn in the SMF of passive galaxies at low masses, usually associated with environmental quenching. We observe two separate populations of passive galaxies evolving on different timescales: roughly half of the high-mass systems were already quenched at high redshift, while low-mass passive galaxies are gradually building up over the redshift range probed. In the framework of environmental quenching at low masses, we interpret this finding as evidence of an increasing role of the environment in the buildup of passive galaxies as a function of time. Finally, we compared our findings with a set of theoretical predictions. Despite good agreement in some redshift and mass intervals, none of the models are able to fully reproduce the observations. This calls for further investigation into the involved physical mechanisms, both theoretically and observationally, especially with the brand-new JWST data.

An Atlas of Color-selected Quiescent Galaxies at z > 3 in Public JWST Fields

“…The difference with previous works is similar in each bin, when available. This is consistent with the expected shape of the stellar mass function of red QGs, roughly peaking and flattening or turning over at ∼10 10.6 M e at these redshifts (Weaver et al 2022a) and revealing a steady buildup of lowermass QGs (Santini et al 2022). Promising low-mass QGs have already been confirmed with JWST/NIRISS at z ∼ 2.5 in the GLASS field (Marchesini et al 2023).…”

CEERS Key Paper. V. Galaxies at 4 < z < 9 Are Bluer than They Appear–Characterizing Galaxy Stellar Populations from Rest-frame ∼1 μm Imaging

“…To test the robustness of the stellar masses and SFRs derived from the BAGPIPES fits, we have refit all the galaxies in our sample using several independent SED-fitting codes (CIGALE, Boquien et al 2019;FAST, Kriek et al 2009; and the codes of Santini et al 2022 andPérez-González et al 2008). Comparing the stellar masses and SFRs, we find they agree in the mean (with bias, μ ; 0 dex) and an inter-method scatter of σ = 0.23 dex in stellar mass and σ = 0.27 dex in SFR.…”

JEMS: A Deep Medium-band Imaging Survey in the Hubble Ultra Deep Field with JWST NIRCam and NIRISS

“…The increased spectral sampling enables better constrained measurements of stellar age due to more accurate tracing of the 4000 Å/Balmer break diagnostic at this key redshift range (see bottom panel of Figure 4). Ground-based limits made this only achievable for the most massive red galaxies (e.g., Esdaile et al 2021), and JWST opens the window to explore quiescence among lower mass galaxies (e.g., Santini et al 2022;Marchesini et al 2023). We thus expect that medium-band imaging at 2 μm will be crucial to identifying the epoch of the emergence of massive quiescent galaxies and reconstructing their star formation histories.…”