We present the second data release of the Large Early Galaxy Astrophysics Census (LEGA-C), an ESO 130−night public spectroscopic survey conducted with VIMOS on the Very Large Telescope. We release ...1988 spectra with typical continuum S/N 20 −1 of galaxies at 0.6 z 1.0, each observed for ∼20 hr and fully reduced with a custom-built pipeline. We also release a catalog with spectroscopic redshifts, emission-line fluxes, Lick/IDS indices, and observed stellar and gas velocity dispersions that are spatially integrated quantities, including both rotational motions and genuine dispersion. To illustrate the new parameter space in the intermediate-redshift regime probed by LEGA-C, we explore relationships between dynamical and stellar population properties. The star-forming galaxies typically have observed stellar velocity dispersions of ∼150 km s−1 and strong Hδ absorption (HδA ∼ 5 ), while passive galaxies have higher observed stellar velocity dispersions (∼200 km s−1) and weak Hδ absorption (HδA ∼ 0 ). Strong O III5007/Hβ ratios tend to occur mostly for galaxies with weak HδA or galaxies with higher observed velocity dispersion. Beyond these broad trends, we find a diversity of possible combinations of rest-frame colors, absorption-line strengths, and emission-line detections, illustrating the utility of spectroscopic measurements to more accurately understand galaxy evolution. By making the spectra and value-added catalogs publicly available we encourage the community to take advantage of this very substantial investment in telescope time provided by ESO.
We present stellar rotation curves and velocity dispersion profiles for 104 quiescent galaxies at z = 0.6-1 from the Large Early Galaxy Astrophysics Census (LEGA-C) spectroscopic survey. Rotation is ...typically probed across 10-20 kpc, or to an average of 2.7Re. Combined with central stellar velocity dispersions ( 0) this provides the first determination of the dynamical state of a sample selected by a lack of star formation activity at large lookback time. The most massive galaxies (M > 2 × 1011 M ) generally show no or little rotation measured at 5 kpc ( V 5 0 < 0.2 in eight of ten cases), while ∼64% of less massive galaxies show significant rotation. This is reminiscent of local fast- and slow-rotating ellipticals and implies that low- and high-redshift quiescent galaxies have qualitatively similar dynamical structures. We compare V 5 0 distributions at z ∼ 0.8 and the present day by re-binning and smoothing the kinematic maps of 91 low-redshift quiescent galaxies from the Calar Alto Legacy Integral Field Area (CALIFA) survey and find evidence for a decrease in rotational support since z ∼ 1. This result is especially strong when galaxies are compared at fixed velocity dispersion; if velocity dispersion does not evolve for individual galaxies then the rotational velocity at 5 kpc was an average of 94 22% higher in z ∼ 0.8 quiescent galaxies than today. Considering that the number of quiescent galaxies grows with time and that new additions to the population descend from rotationally supported star-forming galaxies, our results imply that quiescent galaxies must lose angular momentum between z ∼ 1 and the present, presumably through dissipationless merging, and/or that the mechanism that transforms star-forming galaxies also reduces their rotational support.
Using high-resolution spectra from the VLT Large Early Galaxy Astrophysics Census (LEGA-C) program, we reconstruct the star formation histories (SFHs) of 607 galaxies at redshifts z = 0.6-1.0 and ...stellar masses 1010 M using a custom full spectrum fitting algorithm that incorporates the emcee and FSPS packages. We show that the mass-weighted age of a galaxy correlates strongly with stellar velocity dispersion ( *) and ongoing star formation (SF) activity, with the stellar content in higher- * galaxies having formed earlier and faster. The SFHs of quiescent galaxies are generally consistent with passive evolution since their main SF epoch, but a minority show clear evidence of a rejuvenation event in their recent past. The mean age of stars in galaxies that are star-forming is generally significantly younger, with SF peaking after z < 1.5 for almost all star-forming galaxies in the sample: many of these still have either constant or rising SFRs on timescales >100 Myr. This indicates that z > 2 progenitors of z ∼ 1 star-forming galaxies are generally far less massive. Finally, despite considerable variance in the individual SFHs, we show that the current SF activity of massive galaxies (>L*) at z ∼ 1 correlates with SF levels at least 3 Gyr prior: SFHs retain "memory" on a large fraction of the Hubble time. Our results illustrate a novel approach to resolve the formation phase of galaxies, and, by identifying their individual evolutionary paths, one can connect progenitors and descendants across cosmic time. This is uniquely enabled by the high-quality continuum spectroscopy provided by the LEGA-C survey.
Abstract
We present the first comparison of observed stellar continuum spectra of high-redshift galaxies and mock galaxy spectra generated from hydrodynamical simulations. The mock spectra are ...produced from the IllustrisTNG TNG100 simulation combined with stellar population models and take into account dust attenuation and realistic observational effects (aperture effects and noise). We compare the simulated D
n
4000 and EW(H
δ
) of galaxies with
10.5
≤
log
(
M
*
/
M
⊙
)
≤
11.5
at 0.6 ≤
z
≤ 1.0 to the observed distributions from the LEGA-C survey. TNG100 globally reproduces the observed distributions of spectral indices, implying that the age distribution of galaxies in TNG100 is generally realistic. Yet there are small but significant differences. For old galaxies, TNG100 shows small D
n
4000 when compared to LEGA-C, while LEGA-C galaxies have larger EW(H
δ
) at fixed D
n
4000 . There are several possible explanations: (1) LEGA-C galaxies have overall older ages combined with small contributions (a few percent in mass) from younger (<1 Gyr) stars, while TNG100 galaxies may not have such young subpopulations; (2) the spectral mismatch could be due to systematic uncertainties in the stellar population models used to convert stellar ages and metallicities to observables. In conclusion, the latest cosmological galaxy-formation simulations broadly reproduce the global age distribution of galaxies at
z
∼ 1 and, at the same time, the high quality of the latest observed and simulated data sets help constrain stellar population synthesis models as well as the physical models underlying the simulations.
Genital tuberculosis is a rare and unexpected disease in European countries including Croatia. Diagnosis of female genital tract tuberculosis is challenging and is rarely pin-pointed by clinical ...symptoms because of their low specificity. The authors decided to present a case of genitourinary tuberculosis in a young, immunocompetent fertile woman with high clinical suspicion of abdominal tumor mass. Although considered a desease of the past, rare clinical presentation of genital tuberculosis should be expected and taken into account. Key words: Tuberculosis; Genitourinary tract; Young women; Abdominal tumor
We analyze the colors and sizes of 32 quiescent (UVJ-selected) galaxies with strong Balmer absorption (EW(Hδ) ≥ 4 ) at z ∼ 0.8 drawn from DR2 of the LEGA-C survey to test the hypothesis that these ...galaxies experienced compact, central starbursts before quenching. These recently quenched galaxies, usually referred to as post-starburst galaxies, span a wide range of colors, and we find a clear correlation between color and half-light radius, such that bluer galaxies are smaller. We build simple toy models to explain this correlation: a normal star-forming disk plus a central, compact starburst component. Bursts with exponential decay timescale of ∼100 Myr that produce ∼10% to more than 100% of the preexisting masses can reproduce the observed correlation. More significant bursts also produce bluer and smaller descendants. Our findings imply that when galaxies shut down star formation rapidly, they generally had experienced compact, starburst events and that the large, observed spread in sizes and colors mostly reflects a variety of burst strengths. Recently quenched galaxies should have younger stellar ages in the centers; multiwavelength data with high spatial resolution are required to reveal the age gradient. Highly dissipative processes should be responsible for this type of formation history. While determining the mechanisms for individual galaxies is challenging, some recently quenched galaxies show signs of gravitational interactions, suggesting that mergers are likely an important mechanism in triggering the rapid shutdown of star formation activities at z ∼ 0.8.
•Hydrologic and mechanical properties of pervious concrete were studied.•The optimal aggregate type from the hydrologic point of view is diabase.•An aggregate of sharp grain edges allows the water to ...pass smoothly through the pore system.•A coarser aggregate fraction results in better hydraulic and mechanical properties.
Six mixtures of single-sized pervious concrete were prepared with three different types of aggregates (dolomite, diabase, and steel slag from a Croatian landfill near the town of Sisak) and with two different aggregate fractions (4–8 mm and 8–16 mm). Each pervious concrete mixture contained 10% of sand from the Drava River. The hydrologic properties of the pervious concrete mixtures are compared in order to define the aggregate type that will ensure the best drainage properties. The draining capability was tested by three methods: the constant head and falling head methods on the small samples, and the standard test method for testing the infiltration rate of in-place pervious concrete by ASTM C 1701-09. The possibility of pervious concrete application as a surface layer in pavement construction in the European area is estimated according to the achieved mechanical properties. The optimal aggregate type for preparing pervious concrete from the hydrologic point of view is diabase because of its sharp grain edges, which allow the water to pass smoothly through the pore system. None of the studied mixtures satisfied the set criteria on the mechanical properties of concrete for the surface layer of pavements in the European area. However, it is observed that the coarser aggregate fraction will result in better hydraulic and mechanical properties of pervious concrete.
Special-purpose river port sediment was investigated for its potential use as a road construction material. Sediment samples were extracted from three locations in three small river ports, and ...detailed laboratory research was conducted to determine its basic mechanical properties and characteristics that can potentially have an adverse influence in a roadside environment. The results of the research conducted indicate that there is a need for systematic monitoring of the quality and quantity of sediment in special-purpose river ports of the Danube River Basin to maintain its mobility and prevent flooding. The basic engineering characteristics (Proctor elements, Atterberg limits, California bearing ratio, and unconfined compressive strength) determined represent the good potential of the sediment samples tested herein for use in road construction. In addition, the chemical characteristics tested indicate the need for detailed analyses of the potential environmental risk before application in civil engineering structures
A decade of study has established that the molecular gas properties of star-forming galaxies follow coherent scaling relations out to z ∼ 3, suggesting remarkable regularity of the interplay between ...molecular gas, star formation, and stellar growth. Passive galaxies, however, are expected to be gas-poor and therefore faint, and thus little is known about molecular gas in passive galaxies beyond the local universe. Here we present deep Atacama Large Millimeter/submillimeter Array observations of CO(2-1) emission in eight massive (Mstar ∼ 1011 M ) galaxies at z ∼ 0.7 selected to lie a factor of 3-10 below the star-forming sequence at this redshift, drawn from the Large Early Galaxy Astrophysics Census survey. We significantly detect half the sample, finding molecular gas fractions 0.1. We show that the molecular and stellar rotational axes are broadly consistent, arguing that the molecular gas was not accreted after the galaxies became quiescent. We find that scaling relations extrapolated from the star-forming population overpredict both the gas fraction and gas depletion time for passive objects, suggesting the existence of either a break or large increase in scatter in these relations at low specific star formation rate. Finally, we show that the gas fractions of the passive galaxies we have observed at intermediate redshifts are naturally consistent with evolution into local, massive early-type galaxies by continued low-level star formation, with no need for further gas accretion or dynamical stabilization of the gas reservoirs in the intervening 6 billion years.
Recent studies have found a significant evolution and scatter in the relationship between the UV spectral slope (βUV) and the infrared excess (IRX; LIR/LUV) at z > 4, suggesting different dust ...properties of these galaxies. The total far-infrared (FIR) luminosity is key for this analysis, but it is poorly constrained in normal (main-sequence) star-forming z > 5 galaxies, where often only one single FIR point is available. To better inform estimates of the FIR luminosity, we construct a sample of local galaxies and three low-redshift analogues of z > 5 systems. The trends in this sample suggest that normal high-redshift galaxies have a warmer infrared (IR) spectral energy distribution (SED) compared to average z < 4 galaxies that are used as priors in these studies. The blueshifted peak and mid-IR excess emission could be explained by a combination of a larger fraction of metal-poor interstellar medium being optically thin to ultraviolet (UV) light and a stronger UV radiation field due to high star formation densities. Assuming a maximally warm IR SED suggests a 0.6 dex increase in total FIR luminosities, which removes some tension between the dust attenuation models and observations of the IRX−β relation at z > 5. Despite this, some galaxies still fall below the minimum IRX−β relation derived with standard dust cloud models. We propose that radiation pressure in these highly star-forming galaxies causes a spatial offset between dust clouds and young star-forming regions within the lifetime of O/B stars. These offsets change the radiation balance and create viewing-angle effects that can change UV colors at fixed IRX. We provide a modified model that can explain the location of these galaxies on the IRX−β diagram.
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