- ID:
- ivo://CDS.VizieR/J/MNRAS/443/2679
- Title:
- GEEC2 spectroscopic survey of Galaxy groups
- Short Name:
- J/MNRAS/443/2679
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the data release of the Gemini-South GMOS spectroscopy in the fields of 11 galaxy groups at 0.8<z<1, within the COSMOS field. This forms the basis of the Galaxy Environment Evolution Collaboration 2 (GEEC2) project to study galaxy evolution in haloes with M~10^13^M_{sun}_ across cosmic time. The final sample includes 162 spectroscopically confirmed members with R<24.75, and is >50% complete for galaxies within the virial radius, and with stellar mass M_star_>10^10.3^M_{sun}_. Including galaxies with photometric redshifts, we have an effective sample size of ~400 galaxies within the virial radii of these groups. We present group velocity dispersions, dynamical and stellar masses. Combining with the GCLASS sample of more massive clusters at the same redshift, we find the total stellar mass is strongly correlated with the dynamical mass, with logM_200_=1.20(logM_star_-12)+14.07. This stellar fraction of ~1% is lower than predicted by some halo occupation distribution models, though the weak dependence on halo mass is in good agreement. Most groups have an easily identifiable most massive galaxy (MMG) near the centre of the galaxy distribution, and we present the spectroscopic properties and surface brightness fits to these galaxies. The total stellar mass distribution in the groups, excluding the MMG, compares well with an NFW (Navarro Frenk & White) profile with concentration 4, for galaxies beyond ~0.2R_200_. This is more concentrated than the number density distribution, demonstrating that there is some mass segregation.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/156/224
- Title:
- Gemini/HST GCP: galaxies in 4 massive clusters
- Short Name:
- J/AJ/156/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to study stellar populations and galaxy structures at intermediate and high redshift (z=0.2-2.0) and link these properties to those of low-redshift galaxies, there is a need for well-defined local reference samples. Especially for galaxies in massive clusters, such samples are often limited to the Coma cluster galaxies. We present consistently calibrated velocity dispersions and absorption-line indices for galaxies in the central 2 R_500_x2 R_500_ of four massive clusters at z<0.1: Abell 426/Perseus, Abell 1656/Coma, Abell 2029, and Abell 2142. The measurements are based on data from the Gemini Observatory, McDonald Observatory, and Sloan Digital Sky Survey. For bulge-dominated galaxies, the samples are 95% complete in Perseus and Coma and 74% complete in A2029 and A2142, to a limit of M_B,abs_=<-18.5 mag. The data serve as the local reference for our studies of galaxy populations in the higher-redshift clusters that are part of the Gemini/HST Galaxy Cluster Project (GCP). We establish the scaling relations between line indices and velocity dispersions as a reference for the GCP. We derive stellar population parameters, ages, metallicities [M/H], and abundance ratios from line indices, both averaged in bins of velocity dispersion and from individual measurements for galaxies in Perseus and Coma. The zero points of relations between the stellar population parameters and the velocity dispersions limit the allowed cluster-to-cluster variation of the four clusters to +/-0.08 dex in age, +/-0.06 dex in [M/H], +/-0.07 dex in [CN/Fe], and +/-0.03 dex in [Mg/Fe].
- ID:
- ivo://CDS.VizieR/J/ApJ/858/102
- Title:
- Gemini/NIFS and HST obs. of the galaxy M59-UCD3
- Short Name:
- J/ApJ/858/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the internal properties of the most massive ultracompact dwarf galaxy (UCD), M59-UCD3, by combining adaptive-optics-assisted near-IR integral field spectroscopy from Gemini/NIFS and Hubble Space Telescope (HST) imaging. We use the multiband HST imaging to create a mass model that suggests and accounts for the presence of multiple stellar populations and structural components. We combine these mass models with kinematics measurements from Gemini/NIFS to find a best-fit stellar mass-to-light ratio (M/L) and black hole (BH) mass using Jeans anisotropic models (JAMs), axisymmetric Schwarzschild models, and triaxial Schwarzschild models. The best-fit parameters in the JAM and axisymmetric Schwarzschild models have BHs between 2.5 and 5.9 million solar masses. The triaxial Schwarzschild models point toward a similar BH mass but show a minimum {chi}^2^ at a BH mass of ~0. Models with a BH in all three techniques provide better fits to the central V_rms_ profiles, and thus we estimate the BH mass to be 4.2_-1.7_^+2.1^x10^6^M_{sun}_ (estimated 1{sigma} uncertainties). We also present deep radio imaging of M59-UCD3 and two other UCDs in Virgo with dynamical BH mass measurements, and we compare these to X-ray measurements to check for consistency with the fundamental plane of BH accretion. We detect faint radio emission in M59cO but find only upper limits for M60-UCD1 and M59-UCD3 despite X-ray detections in both these sources. The BH mass and nuclear light profile of M59-UCD3 suggest that it is the tidally stripped remnant of a ~10^9^-10^10^M_{sun}_ galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/772/107
- Title:
- Giant molecular clouds in nearby galaxies
- Short Name:
- J/ApJ/772/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We resolve 182 individual giant molecular clouds (GMCs) larger than 2.5x10^5^M_{sun}_ in the inner disks of 5 large nearby spiral galaxies (NGC 2403, NGC 3031, NGC 4736, NGC 4826, and NGC 6946) to create the largest such sample of extragalactic GMCs within galaxies analogous to the Milky Way. Using a conservatively chosen sample of GMCs most likely to adhere to the virial assumption, we measure cloud sizes, velocity dispersions, and ^12^CO(J=1-0) luminosities and calculate cloud virial masses. The average conversion factor from CO flux to H_2_ mass (or X_CO_) for each galaxy is 1-2x10^20^/cm2 (K.km/s)^-1^, all within a factor of two of the Milky Way disk value (~2x10^20^/cm2(K.km/s)^-1^). We find GMCs to be generally consistent within our errors between the galaxies and with Milky Way disk GMCs; the intrinsic scatter between clouds is of order a factor of two. Consistent with previous studies in the Local Group, we find a linear relationship between cloud virial mass and CO luminosity, supporting the assumption that the clouds in this GMC sample are gravitationally bound. We do not detect a significant population of GMCs with elevated velocity dispersions for their sizes, as has been detected in the Galactic center. Though the range of metallicities probed in this study is narrow, the average conversion factors of these galaxies will serve to anchor the high metallicity end of metallicity-X_CO_ trends measured using conversion factors in resolved clouds; this has been previously possible primarily with Milky Way measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/803/16
- Title:
- Giant molecular clouds in NGC4526 based on ^12^CO
- Short Name:
- J/ApJ/803/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high spatial resolution (~20pc) of ^12^CO(2-1) observations of the lenticular galaxy NGC 4526. We identify 103 resolved giant molecular clouds (GMCs) and measure their properties: size R, velocity dispersion {sigma}_v_, and luminosity L. This is the first GMC catalog of an early-type galaxy. We find that the GMC population in NGC 4526 is gravitationally bound, with a virial parameter {alpha}~1. The mass distribution, dN/dM{propto}M^-2.39+/-0.03^, is steeper than that for GMCs in the inner Milky Way, but comparable to that found in some late-type galaxies. We find no size-line width correlation for the NGC 4526 clouds, in contradiction to the expectation from Larson's relation. In general, the GMCs in NGC 4526 are more luminous, denser, and have a higher velocity dispersion than equal-size GMCs in the Milky Way and other galaxies in the Local Group. These may be due to higher interstellar radiation field than in the Milky Way disk and weaker external pressure than in the Galactic center. In addition, a kinematic measurement of cloud rotation shows that the rotation is driven by the galactic shear. For the vast majority of the clouds, the rotational energy is less than the turbulent and gravitational energy, while the four innermost clouds are unbound and will likely be torn apart by the strong shear at the galactic center. We combine our data with the archival data of other galaxies to show that the surface density {Sigma} of GMCs is not approximately constant, as previously believed, but varies by ~3 orders of magnitude. We also show that the size and velocity dispersion of the GMC population across galaxies are related to the surface density, as expected from the gravitational and pressure equilibrium, i.e., {sigma}_v_R^-1/2^{propto}{Sigma}^1/2^.
- ID:
- ivo://CDS.VizieR/J/ApJ/699/1092
- Title:
- Giant molecular clouds (SRBY)
- Short Name:
- J/ApJ/699/1092
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The properties of Galactic molecular clouds tabulated by Solomon et al. (SRBY; 1987ApJ...319..730S) are re-examined using the Boston University-FCRAO Galactic Ring Survey of ^13^COJ=1-0 emission. These new data provide a lower opacity tracer of molecular clouds and improved angular and spectral resolution compared with previous surveys of molecular line emission along the Galactic Plane. We calculate giant molecular cloud (GMC) masses within the SRBY cloud boundaries assuming local thermodynamic equilibrium (LTE) conditions throughout the cloud and a constant H_2_ to ^13^CO abundance, while accounting for the variation of the ^12^C/^13^C with galactocentric radius.
- ID:
- ivo://CDS.VizieR/J/MNRAS/372/1425
- Title:
- Gravitational lensing analysis of Abell 1689
- Short Name:
- J/MNRAS/372/1425
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived the mass distribution of galaxy cluster Abell 1689 within 0.3h^-1^_70_Mpc of the cluster centre using its strong lensing (SL) effect on 32 background galaxies, which are mapped in altogether 107 multiple images. The multiple images are based on some from the literature with modifications to both include new and exclude some of the original image systems. The cluster profile is explored further out to ~2.5h^-1^_70_Mpc with weak lensing (WL) shear measurements from the literature. The masses of ~200 cluster galaxies are measured with the Fundamental Plane (FP) in order to model accurately the small-scale mass structure in the cluster. The cluster galaxies are modelled as elliptical truncated isothermal spheres. The scalings of the truncation radii with the velocity dispersions of galaxies are assumed to match those of: (i) field galaxies; and (ii) theoretical expectations for galaxies in dense environments. The dark matter (DM) component of the cluster is described by either non-singular isothermal ellipsoids (NSIE) or elliptical versions of the universal DM profile (elliptical Navarro, Frenk & White, ENFW). To account for substructure in the DM we allow for two DM haloes.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/194
- Title:
- Group of galaxies in gravitational lens fields
- Short Name:
- J/ApJ/833/194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With a large, unique spectroscopic survey in the fields of 28 galaxy-scale strong gravitational lenses, we identify groups of galaxies in the 26 adequately sampled fields. Using a group-finding algorithm, we find 210 groups with at least 5 member galaxies; the median number of members is 8. Our sample spans redshifts of 0.04<=z_grp_<=0.76 with a median of 0.31, including 174 groups with 0.1<z_grp_<0.6. The groups have radial velocity dispersions of 60<={sigma}_grp_<=1200km/s with a median of 350km/s. We also discover a supergroup in field B0712+472 at z=0.29 that consists of three main groups. We recover groups similar to ~85% of those previously reported in these fields within our redshift range of sensitivity and find 187 new groups with at least five members. The properties of our group catalog, specifically, (1) the distribution of {sigma}_grp_, (2) the fraction of all sample galaxies that are group members, and (3) the fraction of groups with significant substructure, are consistent with those for other catalogs. The distribution of group virial masses agrees well with theoretical expectations. Of the lens galaxies, 12 of 26 (46%) (B1422+231, B1600+434, B2114+022, FBQS J0951+2635, HE0435-1223, HST J14113+5211, MG0751+2716, MGJ1654+1346, PG 1115+080, Q ER 0047-2808, RXJ1131-1231, and WFI J2033-4723) are members of groups with at least five galaxies, and one more (B0712+472) belongs to an additional, visually identified group candidate. There are groups not associated with the lens that still are likely to affect the lens model; in six of 25 (24%) fields (excluding the supergroup), there is at least one massive ({sigma}_grp_>=500km/s) group or group candidate projected within 2' of the lens.
109. Groups of Galaxies
- ID:
- ivo://CDS.VizieR/J/AJ/113/483
- Title:
- Groups of Galaxies
- Short Name:
- J/AJ/113/483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a friends-of-friends algorithm to identify loose groups from the northern CfA2 survey covering the region 8h<={alpha}_(1950)_<=17h and 8.5{deg}<={delta}_(1950)_<=44.5{deg}. There are 406 groups; 149 of these contains five or more members within the survey. Geometric simulations guide our choice of the selection parameters; {delta}{rho}/{rho}=80 is the limiting density contrast and V0=350km/s is the fiducial velocity linking parameter. The geometric simulations are particularly important for evaluating the impact of large-scale structure (e.g., the Great Wall) on group selection. The physical parameters of this large sample are coincident with our earlier results [126 groups in Ramella et al. (1989ApJ...344...57R)]: the median velocity dispersion in 192 (156; 229)km/s and the median blue log(M/L) is 2.38 (2.20; 2.52). The mass-to-light ratio (M/L) is in units of Msun/Lsun for an assumed Hubble constant, H0=100km/s/Mpc. The numbers in parentheses are 99% confidence limits. This group catalog provides a substantially larger sample for statistical studies than has been previously available. For example, it provides a more substantial sample for estimation of the distribution of group velocity dispersions and of the group-group correlation function. (Copyright) 1997 American Astronomical Society.
- ID:
- ivo://CDS.VizieR/VII/256
- Title:
- Groups of Galaxies from CfA2 Redshift Survey
- Short Name:
- VII/256
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains statistically homogeneous and physically well graunded groups of galaxies based on the CfA2 redshift survey (Cat. J/ApJS/121/287) in the area of space 1000km/s<=cz<=15000km/s, |bII|>=20{deg}. For identification of groups we used a modification of a friends of friends (FoF) method. Principles of friendship and definition of values of presented there free parameters described in Mahtessian (1988Afz....28..255M, 1997Ap.....40..285M). There are 1971 groups with 2 or more members, for a total of 6787 members (46.3%); 765 of the groups have 3 or more members with 4375 galaxies (28.1%). The others 8790 (56.4%) galaxies make a sample of "single" galaxies. The catalog includes group numbers, numbers of members, equatorial coordinates, Virgo-centric radial velocities, line-of-sight-velocity dispersions, integrated group luminosities, and relative quantity of false members.
