Galaxy formation and evolution

Abstract:

Abstract Cosmic filaments have been recognised as influencing galaxy evolution, but their connection to galactic cold gas reservoirs is elusive, particularly at low redshifts. We investigate the influence of filaments on neutral hydrogen (H i) detections in galaxies at 0.02 < z < 0.09, using the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey in the COSMOS and XMM-LSS fields. We measure the fraction of optical galaxies from the Dark Energy Spectroscopic Instrument (DESI) Survey detected in H i emission as a function of stellar mass, morphology, local density, and the distance to the nearest filament. We find that galaxies closer to filaments have higher stellar masses, higher local densities, and a larger early-type fraction, all of which affect the H i detection. After controlling for these dependencies, filaments have measurable effects on H i detection. Late-type galaxies in low-local density environments show reduced H i detection fractions close to filaments across all stellar mass ranges, suggesting potential gas depletion through ram pressure stripping and cosmic web detachment. Massive early-type galaxies show an enhanced H i detection fraction in filaments compared to the voids, suggesting possible gas replenishment through filamentary accretion or gas-rich mergers. Our results suggest that cosmic filaments influence galactic H i gas reservoirs through various competing processes, whose relative importance varies with stellar mass and local density.

Abstract:

The James Webb Space Telescope (JWST) has extended the frontier of galaxy detection to redshifts z > 11, finding a high abundance of UV-bright sources that challenge theoretical models. However, most current results come from just a few fields, introducing uncertainties due to cosmic variance. Here, we constrain z ∼ 7–14 UV luminosity functions (LFs) over ∼400 arcmin2 across 36 independent sight lines from Data Release 2 of BEACON, a JWST pure-parallel NIRCam multiband imaging survey. We identify 164 7 < z < 12 galaxy candidates: 150 F090W, 14 F115W, and no robust F150W dropouts. In the 11 pointings overlapping with public JWST spectroscopy, we find no contaminants, indicating a high purity in our sample. Our z ∼ 7.5 UV LF agrees with previous bright-end measurements but yields lower number densities at −21 ≤ MUV ≤ −19. At z ∼ 10, our measurements are lower than most photometric JWST results but match spectroscopic constraints, consistent with the high purity of our selection. The LFs at z ∼ 7.5 and 10 are consistent with pre-JWST models, while our limits at z > 13 do not rule out a possible excess. We measure significant clustering of bright (MUV < −20.5) galaxies at 7 < z < 10. Fields hosting such sources are approximately 3 times more likely to be overdense relative to the full survey, implying that UV-bright galaxies preferentially reside in the most massive halos at these redshifts. Comparing with seminumerical simulations, we estimate that MUV < −20.5 galaxies inhabit halos ∼0.8 dex less massive at z ∼ 11 than at z ∼ 8, consistent with a shift to higher star formation rates. However, their observed clustering exceeds predictions from pre-JWST luminosity–halo mass relations, suggesting these sources reside in more massive halos than previously modelled and/or multiple halo occupation.

Abstract:

We present the star formation and dust content properties for a sample of 646 galaxies at redshifts 3 < z < 7 as part of the JADES survey. Our analysis is based on measurements of the Hα/Hβ Balmer decrement using medium resolution (R ∼ 1000) spectroscopic observations with the JWST/NIRSpec microshutter assembly. Stellar masses and star formation rates (SFRs) are inferred with Prospector using deep multiband imaging. We utilize the Balmer decrement to measure dust-corrected Hα-based SFRs, taking into account the subsolar metallicities observed in galaxies at high redshift. We confirm, with our large sample size, that the correlation between the Balmer decrement and stellar mass is already established out to z ∼ 7. We find that the relation between the Balmer decrement and stellar mass does not significantly evolve from the local Universe to z ∼ 7. We investigate the UV slope as a function of the Balmer optical depth and find that the best-fit correlation for our high redshift sample is specific SFR (sSFR) dependent and significantly different at high redshift when compared to galaxies at z ≈ 0 and z ≈ 2. For the highest sSFR galaxies in our sample, there is no significant correlation between the UV slope and Balmer optical depth. This is evidence that the UV slope should be used with great caution to correct for dust in high redshift galaxies.

Abstract:

We present a sample of 213 early-type galaxies (ETGs) at redshifts 0.25 < z < 0.75. We combine deep integral-field spectroscopy from the MUSE-DEEP survey with high-resolution Hubble Space Telescope (HST) imaging to study the structure, kinematics, and stellar populations of these galaxies. We measure spatially resolved stellar kinematics and use the specific angular momentum proxy, λR, to classify galaxies into fast and slow rotators. The kinematic and photometric axes of fast rotators are generally well aligned, similar to their local counterparts. We find that global stellar population properties, such as age, metallicity, and mass-to-light ratio (M*/L), correlate strongly with the central velocity dispersion (σe), following trends established for local ETGs. Slow rotators are typically more massive, have higher σe, and are more metal rich than fast rotators. We also find a slow rotator fraction consistent with local Universe samples. Our findings indicate that the fundamental structural, kinematic, and stellar population scaling relations of massive ETGs were already in place by z ∼ 0.75, suggesting their evolutionary pathways have remained stable over the last ∼7 Gyr.