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Dynamical models for 673 galaxies at z = 0.6â€"1.0 with spatially resolved (long-slit) stellar kinematic data from LEGA-C are used to calibrate virial mass estimates defined as M vir = K σ ′ ⋆ , int 2 R , with K a scaling factor, σ ′ ⋆ , int the spatially integrated stellar velocity second moment from the LEGA-C survey, and R the effective radius measured from a SĂ©rsic profile fit to Hubble Space Telescope imaging. The sample is representative for M ⋆ > 3 Ă— 1010 M ⊙ and includes all types of galaxies, irrespective of morphology and color. We demonstrate that using R = R sma (the semimajor axis length of the ellipse that encloses 50% of the light) in combination with an inclination correction on σ ′ ⋆ , int produces an unbiased M vir. We confirm the importance of projection effects on σ ′ ⋆ , int by showing the existence of a similar residual trend between virial mass estimates and inclination for the nearby early-type galaxies in the ATLAS3D survey. Also, as previously shown, when using a SĂ©rsic profile-based R estimate, a SĂ©rsic index-dependent correction to account for nonhomology in the radial profiles is required. With respect to analogous dynamical models for low-redshift galaxies from the ATLAS3D survey we find a systematic offset of 0.1 dex in the calibrated virial constant for LEGA-C, which may be due to physical differences between the galaxy samples or an unknown systematic error. Either way, with our work we establish a common mass scale for galaxies across 8 Gyr of cosmic time with a systematic uncertainty of at most 0.1 dex. [ABSTRACT FROM AUTHOR]

We compare dynamical mass estimates based on spatially extended stellar and ionized gas kinematics (M dyn,* and M dyn,eml, respectively) of 157 star-forming galaxies at 0.6 ≤ z < 1. Compared with z ∼ 0, these galaxies have enhanced star formation rates, with stellar feedback likely affecting the dynamics of the gas. We use LEGA-C DR3, the highest-redshift data set that provides sufficiently deep measurements of a K s -band limited sample. For M dyn,*, we use Jeans anisotropic multi-Gaussian expansion models. For M dyn,eml, we first fit a custom model of a rotating exponential disk with uniform dispersion, whose light is projected through a slit and corrected for beam smearing. We then apply an asymmetric drift correction based on assumptions common in the literature to the fitted kinematic components to obtain the circular velocity, assuming hydrostatic equilibrium. Within the half-light radius, M dyn,eml is on average lower than M dyn,*, with a mean offset of â€"0.15 ± 0.016 dex and galaxy-to-galaxy scatter of 0.19 dex, reflecting the combined random uncertainty. While data of higher spatial resolution are needed to understand this small offset, it supports the assumption that the galaxy-wide ionized gas kinematics do not predominantly originate from disruptive events such as star formationâ€"driven outflows. However, a similar agreement can be obtained without modeling from the integrated emission line dispersions for axis ratios q < 0.8. This suggests that our current understanding of gas kinematics is not sufficient to efficiently apply asymmetric drift corrections to improve dynamical mass estimates compared with observations lacking the signal-to-noise ratio required for spatially extended dynamics. [ABSTRACT FROM AUTHOR]

Galaxy evolution is driven by a variety of physical processes that are predicted to proceed at different rates for different dark matter haloes and environments across cosmic times. A record of this evolution is preserved in galaxy stellar populations, which we can access using absorption-line spectroscopy. Here we explore the large LEGA-C survey (DR3) to investigate the role of the environment and stellar mass on stellar populations at z ∼ 0.6–1 in the COSMOS field. Leveraging the statistical power and depth of LEGA-C, we reveal significant gradients in Dn4000 and Hδ equivalent widths (EWs) distributions over the stellar mass versus environment 2D spaces for the massive galaxy population (M > 1010M⊙) at z ∼ 0.6–1.0. Dn4000 and Hδ EWs primarily depend on stellar mass, but they also depend on environment at fixed stellar mass. By splitting the sample into centrals and satellites, and in terms of star-forming galaxies and quiescent galaxies, we reveal that the significant environmental trends of Dn4000 and Hδ EW, when controlling for stellar mass, are driven by quiescent galaxies. Regardless of being centrals or satellites, star-forming galaxies reveal Dn4000 and Hδ EWs, which depend strongly on their stellar mass and are completely independent of the environment at 0.6 < z < 1.0. The environmental trends seen for satellite galaxies are fully driven by the trends that hold only for quiescent galaxies, combined with the strong environmental dependency of the quiescent fraction at fixed stellar mass. Our results are consistent with recent predictions from simulations that point toward massive galaxies forming first in overdensities or the most compact dark matter haloes. [ABSTRACT FROM AUTHOR]

Galaxy evolution is driven by a variety of physical processes that are predicted to proceed at different rates for different dark matter haloes and environments across cosmic times. A record of this evolution is preserved in galaxy stellar populations, which we can access using absorption-line spectroscopy. Here we explore the large LEGA-C survey (DR3) to investigate the role of the environment and stellar mass on stellar populations at z ∼ 0.6â€"1 in the COSMOS field. Leveraging the statistical power and depth of LEGA-C, we reveal significant gradients in D n 4000 and H δ equivalent widths (EWs) distributions over the stellar mass versus environment 2D spaces for the massive galaxy population (M > 1010 M ⊙) at z ∼ 0.6â€"1.0. D n 4000 and H δ EWs primarily depend on stellar mass, but they also depend on environment at fixed stellar mass. By splitting the sample into centrals and satellites, and in terms of star-forming galaxies and quiescent galaxies, we reveal that the significant environmental trends of D n 4000 and H δ EW, when controlling for stellar mass, are driven by quiescent galaxies. Regardless of being centrals or satellites, star-forming galaxies reveal D n 4000 and H δ EWs, which depend strongly on their stellar mass and are completely independent of the environment at 0.6 < z < 1.0. The environmental trends seen for satellite galaxies are fully driven by the trends that hold only for quiescent galaxies, combined with the strong environmental dependency of the quiescent fraction at fixed stellar mass. Our results are consistent with recent predictions from simulations that point toward massive galaxies forming first in overdensities or the most compact dark matter haloes. [ABSTRACT FROM AUTHOR]

We present spatially resolved stellar kinematics for 797 z = 0.6â€"1 galaxies selected from the LEGA-C survey and construct axisymmetric Jeans models to quantify their dynamical mass and degree of rotational support. The survey is K s -band selected, irrespective of color or morphological type, and allows for a first assessment of the stellar dynamical structure of the general L * galaxy population at large look-back time. Using light profiles from Hubble Space Telescope imaging as a tracer, our approach corrects for observational effects (seeing convolution and slit geometry), and uses well-informed priors on inclination, anisotropy, and a non-luminous mass component. Tabulated data include total mass estimates in a series of spherical apertures (1, 5, and 10 kpc; 1 Ă— and 2 Ă— R e), as well as rotational velocities, velocity dispersions, and anisotropy. We show that almost all star-forming galaxies and ∼50% of quiescent galaxies are rotation dominated, with deprojected V / σ ∼ 1â€"2. Revealing the complexity in galaxy evolution, we find that the most massive star-forming galaxies are among the most rotation dominated, and the most massive quiescent galaxies among the least rotation-dominated galaxies. These measurements set a new benchmark for studying galaxy evolution, using stellar dynamical structure for galaxies at large look-back time. Together with the additional information on stellar population properties from the LEGA-C spectra, the dynamical mass and V / σ measurements presented here create new avenues for studying galaxy evolution at large look-back time. [ABSTRACT FROM AUTHOR]

We explore the connection between the kinematics, structures and stellar populations of massive galaxies at 0.6 < z < 1.0 using the fundamental plane (FP). Combining stellar kinematic data from the Large Early Galaxy Astrophysics Census (LEGA-C) survey with structural parameters measured from deep Hubble Space Telescope imaging, we obtain a sample of 1419 massive () galaxies that span a wide range in morphology, star formation activity, and environment, and therefore is representative of the massive galaxy population at z ∼ 0.8. We find that quiescent and star-forming galaxies occupy the parameter space of the g-band FP differently and thus have different distributions in the dynamical mass-to-light ratio (Mdyn/Lg), largely owing to differences in the stellar age and recent star formation history, and to a lesser extent, the effects of dust attenuation. In contrast, we show that both star-forming and quiescent galaxies lie on the same mass FP at z ∼ 0.8, with a comparable level of intrinsic scatter about the plane. We examine the variation in Mdyn/M* through the thickness of the mass FP, finding no significant residual correlations with stellar population properties, Sérsic index, or galaxy overdensity. Our results suggest that, at fixed size and velocity dispersion, the variations in Mdyn/Lg of massive galaxies reflect an approximately equal contribution of variations in M*/Lg, and variations in the dark matter fraction or initial mass function. [ABSTRACT FROM AUTHOR]

We study the mass–metallicity relation for 19 members of a spectroscopically confirmed protocluster in the COSMOS field at z = 2.2 (CC2.2), and compare it with that of 24 similarly selected field galaxies at the same redshift. Both samples are Hα emitting sources, chosen from the HiZELS narrowband survey, with metallicities derived from the line ratio. For the mass-matched samples of protocluster and field galaxies, we find that protocluster galaxies with 109.9M⊙ ≤ M* ≤ 1010.9M⊙ are metal deficient by 0.10 ± 0.04 dex (2.5σ significance) compared to their coeval field galaxies. This metal deficiency is absent for low-mass galaxies, M* < 109.9M⊙. Moreover, relying on both spectral energy distribution derived and Hα (corrected for dust extinction based on M*) star formation rates (SFRs), we find no strong environmental dependence of the SFR–M* relation; however, we are not able to rule out the existence of small dependence due to inherent uncertainties in both SFR estimators. The existence of 2.5σ significant metal deficiency for massive protocluster galaxies favors a model in which funneling of the primordial cold gas through filaments dilutes the metal content of protoclusters at high redshifts (z ≳ 2). At these redshifts, gas reservoirs in filaments are dense enough to cool down rapidly and fall into the potential well of the protocluster to lower the gas-phase metallicity of galaxies. Moreover, part of this metal deficiency could be originated from galaxy interactions that are more prevalent in dense environments. [ABSTRACT FROM AUTHOR]

We conducted submillimeter observations with the Atacama Large Millimeter/submillimeter Array (ALMA) of star-forming galaxies at z ∼ 3.3, whose gas-phase metallicities have been measured previously. We investigated the dust and gas contents of the galaxies at z ∼ 3.3 and studied the interaction of galaxies with their circumgalactic or intergalactic medium at this epoch by probing their gas mass fractions and gas-phase metallicities. Single-band dust continuum emission tracing dust mass and the relation between the gas-phase metallicity and gas-to-dust mass ratio were used to estimate the gas masses. The estimated gas mass fractions and depletion timescales are fgas= 0.20–0.75 and tdep= 0.09–1.55 Gyr. Although the galaxies appear to be tightly distributed around the star-forming main sequence at z ∼ 3.3, both quantities show a wider spread at a fixed stellar mass than expected from the scaling relation, suggesting a large diversity of fundamental gas properties in star-forming galaxies that apparently lie on the main sequence. When we compared gas mass fraction and gas-phase metallicity in star-forming galaxies at z ∼ 3.3 and at lower redshifts, star-forming galaxies at z ∼ 3.3 appear to be more metal poor than local galaxies with similar gas mass fractions. Using the gas regulator model to interpret this offset, we find that this can be explained by a higher mass-loading factor, suggesting that the mass-loading factor in outflows increases at earlier cosmic times. [ABSTRACT FROM AUTHOR]

We present a novel approach to measure the attenuation curves of 485 individual star-forming galaxies with > 1010 M⊙ based on deep optical spectra from the VLT/VIMOS LEGA-C survey and multiband photometry in the COSMOS field. Most importantly, we find that the attenuation curves in the rest-frame 3000–4500 Å range are typically almost twice as steep as the Milky Way, LMC, SMC, and Calzetti attenuation curves, which is in agreement with recent studies of the integrated light of present-day galaxies. The attenuation at 4500 Å and the slope strongly correlate with the galaxy inclination: face-on galaxies show less attenuation and steeper curves compared to edge-on galaxies, suggesting that geometric effects dominate observed variations in attenuation. Our new method produces 2175 Å UV bump detections for 260 individual galaxies. Even though obvious correlations between UV bump strength and global galaxy properties are absent, strong UV bumps are most often seen in face-on, lower-mass galaxies (10 < log10(M*/M⊙) < 10.5) with low overall attenuation. Finally, we produce a typical attenuation curve for star-forming galaxies at z ∼ 0.8; this prescription represents the effect of dust on the integrated spectral energy distributions of high-redshift galaxies more accurately than commonly used attenuation laws. [ABSTRACT FROM AUTHOR]

We use reconstructed star formation (SF) histories of quiescent galaxies at z = 0.6–1 in the Large Early Galaxy Astrophysics Census survey to identify secondary SF episodes that, after an initial period of quiescence, moved the galaxies back to the star-forming main sequence (blue cloud). 16 ± 3% of the z ∼ 0.8 quiescent population has experienced such rejuvenation events in the redshift range of 0.7 < z < 1.5 after reaching quiescence at some earlier time. On average, these galaxies first became quiescent at z = 1.2, and those that rejuvenated, remained quiescent for ∼1 Gyr before their secondary SF episode, which lasted ∼0.7 Gyr. The stellar mass attributed to rejuvenation is on average 10% of the galaxy stellar mass, with rare instances of an increase of more than a factor of 2. Overall, rejuvenation events only contribute ∼2% of the total stellar mass in z ∼ 0.8 quiescent galaxies and we conclude that rejuvenation is not an important evolutionary channel when considering the growth of the red sequence. However, our results complicate the interpretation of galaxy demographics in color space: the galaxies with rejuvenation events tend to lie in the so-called "green valley," yet their progenitors were quiescent at z ∼ 2. [ABSTRACT FROM AUTHOR]

The galaxy cluster CIZA J2242.8+5301 at z = 0.19 is a merging system with a prominent (∼2 Mpc long) radio relic, which together with the morphology of the X-ray emission provides strong evidence for a violent collision along the north-south axis. We present our constraints on the dark matter distribution of this unusual system using Subaru and Canada-France-Hawaii Telescope imaging data. Measuring a high signal-to-noise ratio lensing signal from this cluster is potentially a challenging task because of its proximity to the Milky Way plane (|b| ∼ 5°). We overcome this challenge with careful observation planning and systematics control, which enables us to successfully map the dark matter distribution of the cluster with high fidelity. The resulting mass map shows that the mass distribution of CIZA J2242.8+5301 is highly elongated along the north-south merger axis inferred from the orientation of the radio relics. Based on our mass reconstruction, we identify two sub-clusters, which coincide with the cluster galaxy distributions. We determine their masses using Markov Chain Monte Carlo analysis by simultaneously fitting two Navarro-Frenk-White halos without fixing their centroids. The resulting masses of the northern and southern systems are and , respectively, indicating that we are witnessing a post-collision of two giant systems of nearly equal mass. When the mass and galaxy centroids are compared in detail, we detect ∼1′ (∼190 kpc) offsets in both northern and southern sub-clusters. After investigating the statistical significance of the offsets by bootstrapping both mass and galaxy centroids, we find that the galaxy luminosity-mass offset for the northern clump is statistically significant at the ≳ 2σ level whereas the detection is only marginal for the southern sub-cluster in part because of a relatively large mass centroid error. We conclude that it is yet premature to uniquely attribute the galaxy-mass misalignment to self-interaction of dark matter and discuss caveats. [ABSTRACT FROM AUTHOR]