Search

We present spatially resolved, simple stellar population equivalent ages, stellar metallicities, and abundance ratios for 456 massive (⁠|$10.3\lesssim \log (\mathrm{M}_*/\mathrm{M}_\odot)\lesssim 11.8$|⁠) quiescent galaxies at |$0.6\lesssim z\lesssim 1.0$| from the Large Early Galaxy Astrophysics Census, derived using full-spectrum models. Typically, we find flat age and [Mg/Fe] gradients, and negative [Fe/H] gradients, implying iron-rich cores. We also estimate intrinsic [Fe/H] gradients via forward modelling. We examine the observed gradients in three age bins. Younger quiescent galaxies typically have negative [Fe/H] gradients and positive age gradients, possibly indicating a recent central starburst. Additionally, this finding suggests that photometrically measured flat colour gradients in young quiescent galaxies are the result of the positive age and negative metallicity gradients cancelling each other. For older quiescent galaxies, the age gradients become flat and [Fe/H] gradients weaken, though remain negative. Thus, negative colour gradients at older ages are likely driven by metallicity gradients. The diminishing age gradient may result from the starburst fading. Furthermore, the persistence of the [Fe/H] gradients may suggest that the outskirts are simultaneously built up by mergers with lower metallicity satellites. On the other hand, the gradients could be inherited from the star-forming phase, in which case mergers may not be needed to explain our findings. This work illustrates the need for resolved spectroscopy, instead of just photometry, to measure stellar population gradients. Extending these measurements to higher redshift is imperative for understanding how stellar populations in quiescent galaxies are assembled over cosmic time. [ABSTRACT FROM AUTHOR]

Over the past year, JWST has uncovered galaxies at record-breaking distances up to z ∼ 13. The JWST UNCOVER (ultra-deep NIRSpec and NIRcam observations before the epoch of reionization) program has obtained ultra-deep multiwavelength NIRCam imaging of the massive galaxy cluster A2744 over ∼45 arcmin2 down to ∼29.5 AB mag. Here, we present a robust ultraviolet (UV) luminosity function derived through lensing clusters at 9 < z < 12. Using comprehensive end-to-end simulations, we account for all lensing effects and systematic uncertainties in deriving both the amplification factors and the effective survey volume. Our results confirm the intriguing excess of UV-bright galaxies (M UV <−20 AB mag) previously reported at z > 9 in recent JWST studies. In particular, a double power-law (DPL) describes better the bright end of the luminosity function compared to the classical Schechter form. The number density of these bright galaxies is 10–100 times larger than theoretical predictions and previous findings based on Hubble Space Telescope (HST) observations. Additionally, we measure a star formation rate density of ρSFR = 10−2.64 M⊙ yr−1 Mpc−3 at these redshifts, which is 4–10 times higher than galaxy formation models that assume a constant star formation efficiency. Future wide-area surveys and accurate modelling of lensing-assisted observations will reliably constrain both the bright and the dim end of the UV luminosity function at z > 9, which will provide key benchmarks for galaxy formation models. [ABSTRACT FROM AUTHOR]

We compare ionized gas and stellar kinematics of 16 star-forming galaxies (log (M ⋆/ M ⊙) = 9.7–11.2, SFR =6 − 86 M⊙ yr−1) at z ∼ 1 using near-infrared integral field spectroscopy (IFS) of Hα emission from the KMOS3D (the K-band Multi-Object Spectrograph 3D) survey and optical slit spectroscopy of stellar absorption and gas emission from the LEGA-C (Large Early Galaxy Astrophysics Census) survey. Hα is dynamically colder than stars, with higher disc rotation velocities (by ∼45 per cent) and lower disc velocity dispersions (by a factor ∼2). This is similar to trends observed in the local Universe. We find higher rotational support for Hα relative to [O  ii ], potentially explaining systematic offsets in kinematic scaling relations found in the literature. Regarding dynamical mass measurements, for six galaxies with cumulative mass profiles from Jeans Anisotropic Multi-Gaussian Expansion (JAM) models the Hα dynamical mass models agree remarkably well out to ∼10 kpc for all but one galaxy (average |$\Delta M_{\rm dyn}(R_{e,\rm F814W})\lt 0.1$| dex). Simpler dynamical mass estimates based on integrated stellar velocity dispersion are less accurate (standard deviation 0.24 dex). Differences in dynamical mass estimates are larger, for example, for galaxies with stronger misalignments of the Hα kinematic major axis and the photometric position angle, highlighting the added value of IFS observations for dynamics studies. The good agreement between the JAM and the dynamical models based on Hα kinematics at z ∼ 1 corroborates the validity of dynamical mass measurements from Hα IFS observations, which can be more easily obtained for higher redshift galaxies. [ABSTRACT FROM AUTHOR]