We present the curation and verification of a new combined optical and near infrared dataset for cosmology and astrophysics, derived by combining ugri-band imaging from the Kilo-Degree Survey (KiDS) and ZYJHKs-band imaging from the VISTA Kilo degree Infrared Galaxy (VIKING) survey. This dataset is unrivaled in cosmological imaging surveys due to the combination of its area (458 deg2 before masking), depth (r<=25), and wavelength coverage (ugriZYJHKs). This combination of survey depth, area, and (most importantly) wavelength coverage allows significant reductions in systematic uncertainties (i.e. reductions of between 10% and 60% in bias, outlier rate, and scatter) in photometric-to-spectroscopic redshift comparisons, compared to the optical-only case at photo-z above 0.7. The complementarity between our optical and near infrared surveys means that over 80% of our sources, across all photo-z, have significant detections (i.e. not upper limits) in our eight reddest bands. We have derived photometry, photo-z, and stellar masses for all sources in the survey, and verified these data products against existing spectroscopic galaxy samples. We demonstrate the fidelity of our higher-level data products by constructing the survey stellar mass functions in eight volume-complete redshift bins. We find that these photometrically derived mass functions provide excellent agreement with previous mass evolution studies derived using spectroscopic surveys. The primary data products presented in this paper are made publicly available through the KiDS survey website.
We continue to study star formation in dwarf galaxies located in nearby clusters. Known physical and chemical relations outlining the formation and evolution of dwarfs is compared in different environments, including the Local Volume (LV) and some nearby clusters studied previously. We used the TNG telescope for four nights in 2010 to acquire deep near-infrared imaging in K' of 45 star forming dwarf galaxies located in the Abell 779, Abell 1367, Abell 1656 (Coma), and Abell 2151 (Hercules) clusters. Surface photometry was approached based on past experience by using the sech law to account for the outer old stellar contribution plus a Gaussian component to model the inner starburst, proving the blue compact dwarf (BCD) classification of most targets. Sech central surface brightness, semimajor axis, sech, and total apparent magnitude were measured, allowing to estimate size, absolute luminosity and mass for all targets. The physical correlations between size, central brightness, and NIR luminosity appear to hold, but previously known linear fits break above M_SK_=-19 for Abell 779, Abell 1367 and especially for Hercules, while the dwarf fundamental plane (FP) is probed by only half cluster members, suggesting harassment by the denser cluster environments. Nevertheless, the chemical relations between the oxygen abundance, luminosity, gas mass, baryonic mass, and gas fraction in a closed box model are probed by most members of the four studied clusters, and the starburst grows linearly with the K' luminosity.
Kimematics of horizontal-branch stars from SDDSS-DR7
Short Name:
J/AJ/140/500
Date:
21 Oct 2021
Publisher:
CDS
Description:
On the basis of a recently derived color-metallicity relation and stellar parameters from the Sloan Digital Sky Survey Data Release 7 spectroscopic survey, a large sample of red horizontal-branch (RHB) candidates have been selected to serve as standard candles. The metallicity and kinematic distributions of these stars indicate that they mainly originate from the thick-disk and the halo populations.
As part of an ongoing program on the main parameters of early-type galaxies, we have performed long-slit absorption spectroscopy on a sample of 21 ellipticals and S0s. We present determinations of the central velocity dispersion and, for 18 objects, velocity-dispersion profiles and rotation curves.
We present new kinematical data for a sample of 38 early-type galaxies. Rotation curves and velocity-dispersion profiles are determined for 32 objects, while the central velocity dispersions are given for the whole sample. This is our second paper in a series devoted to the presentation of kinematical data on elliptical and S0 galaxies, derived from long-slit absorption spectroscopy.
We present new kinematical data for a sample of 24 early-type galaxies. Rotation curves and velocity-dispersion profiles are determined for 21 objects, while the central velocity dispersions are given for the whole sample. This is our third paper in a series devoted to the presentation of kinematical data on elliptical and S0 galaxies, derived from long-slit absorption spectroscopy.
We present kinematical data for a sample of 25 galaxies. Rotation curves and velocity-dispersion profiles are determined for 16 objects, while the central velocity dispersions are given for the whole sample. This is our fourth paper in a series devoted to the presentation of kinematical data on elliptical and S0 galaxies, derived from long-slit absorption spectroscopy.
We present kinematical data for a sample of 26 galaxies. Rotation curves and velocity-dispersion profiles are determined for all objects. This is our fifth paper in a series devoted to the presentation of data on elliptical and S0 galaxies, derived from long-slit absorption spectroscopy; the series now gathers 119 galaxies with homogeneous data.
We present the result of spectroscopic observations of a sample of 73 galaxies, completing the database published in this series of articles. The sample contains mostly low-luminosity early-type objects, including four dwarfs of the Local Group (in particular, deep spectra of NGC 205), 15 dEs or dS0s in the Virgo cluster, and UGC 05442, a spheroidal dwarf of the M81 group. We have measured the central velocity dispersion for all but one object, and determined the major-axis rotation and velocity-dispersion profiles for 59 objects. For the current sample of diffuse (or dwarf) elliptical galaxies, we have compared stellar rotation to velocity dispersion; the analysis suggests that these objects may be nearly rotationally flattened, and therefore that anisotropy may be less important than previously thought.
We present new radial velocities for 203 galaxies in 105 pairs and 2 triplets. The majority are close pairs of early-type galaxies; there are also pairs including a giant spiral galaxy (generally M51 type), and a few are wide pairs of early-type galaxies. Most velocities were measured from the absorption lines in the region of Mgb; emission-line velocities are also given for 22 galaxies. The velocity of one component only was measured in 13 (generally hierarchical) pairs. Velocity dispersions were measured for a subsample of 18 close pairs of early-type galaxies.