ﻻ يوجد ملخص باللغة العربية
We investigate the stellar populations for a sample of 161 massive, mainly quiescent galaxies at $langle z_{rm obs} rangle=0.8$ with deep Keck/DEIMOS rest-frame optical spectroscopy (HALO7D survey). With the fully Bayesian framework Prospector, we simultaneously fit the spectroscopic and photometric data with an advanced physical model (including non-parametric star-formation histories, emission lines, variable dust attenuation law, and dust and AGN emission) together with an uncertainty and outlier model. We show that both spectroscopy and photometry are needed to break the dust-age-metallicity degeneracy. We find a large diversity of star-formation histories: although the most massive ($M_{star}>2times10^{11}~M_{odot}$) galaxies formed the earliest (formation redshift of $z_{rm f}approx5-10$ with a short star-formation timescale of $tau_{rm SF}lesssim1~mathrm{Gyr}$), lower-mass galaxies have a wide range of formation redshifts, leading to only a weak trend of $z_{rm f}$ with $M_{star}$. Interestingly, several low-mass galaxies with have formation redshifts of $z_{rm f}approx5-8$. Star-forming galaxies evolve about the star-forming main sequence, crossing the ridgeline several times in their past. Quiescent galaxies show a wide range and continuous distribution of quenching timescales ($tau_{rm quench}approx0-5~mathrm{Gyr}$) with a median of $langletau_{rm quench}rangle=1.0_{-0.9}^{+0.8}~mathrm{Gyr}$ and of quenching epochs of $z_{rm quench}approx0.8-5.0$ ($langle z_{rm quench}rangle=1.3_{-0.4}^{+0.7}$). This large diversity of quenching timescales and epochs points toward a combination of internal and external quenching mechanisms. In our sample, rejuvenation and late bloomers are uncommon. In summary, our analysis supports the grow & quench framework and is consistent with a wide and continuously-populated diversity of quenching timescales.
(Abridged) We explore 7 clusters from LoCuSS at z~0.2 with spectra of 1965 cluster members from the ACReS Hectospec survey covering a region which corresponds to about three virial radii for each cluster. We measure fluxes of five emission lines of c
We present a comparison of the observed, spatially integrated stellar and ionized gas velocity dispersions of $sim1000$ massive ($log M_{star}/M_{odot}gtrsim,10.3$) galaxies in the Large Early Galaxy Astrophysics Census (LEGA-C) survey at $0.6lesssim
We present near-infrared spectroscopic confirmations of a sample of 16 photometrically-selected galaxies with stellar masses log(M_star/M_sun) > 11 at redshift z > 3 from the XMM-VIDEO and COSMOS-UltraVISTA fields using Keck/MOSFIRE as part of the MA
For early-type galaxies, the ability to sustain a corona of hot, X-ray emitting gas could have played a key role in quenching their star-formation history. Yet, it is still unclear what drives the precise amount of hot gas around these galaxies. By c
We present a detailed study of the molecular gas content and stellar population properties of three massive galaxies at 1 < z < 1.3 that are in different stages of quenching. The galaxies were selected to have a quiescent optical/near-infrared spectr