- ID:
- ivo://CDS.VizieR/J/ApJ/843/16
- Title:
- Galaxy groups within 3500km/s
- Short Name:
- J/ApJ/843/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A study of the group properties of galaxies in our immediate neighborhood provides a singular opportunity to observationally constrain the halo mass function, a fundamental characterization of galaxy formation. Detailed studies of individual groups have provided the coefficients of scaling relations between a proxy for the virial radius, velocity dispersion, and mass that usefully allow groups to be defined over the range 10^10^-10^15^M_{sun}_. At a second hierarchical level, associations are defined as regions around collapsed halos extending to the zero-velocity surface at the decoupling from cosmic expansion. The most remarkable result of the study emerges from the construction of the halo mass function from the sample. At ~10^12^M_{sun}_, there is a jog from the expectation Sheth-Tormen function, such that halo counts drop by a factor ~3 in all lower mass bins.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/337/256
- Title:
- Galaxy in low X-ray luminosity clusters
- Short Name:
- J/MNRAS/337/256
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first spectroscopic survey of intrinsically low X-ray luminosity clusters at z>>0, with Hubble Space Telescope (HST) WFPC2 imaging and spectroscopy from Calar Alto and WHT-LDSS2. We study 172 confirmed cluster members in a sample of ten clusters at 0.23<z<0.3, with LX<~4x10^43^h^-2^erg/s[0.1-2.4keV]. The core of each cluster is imaged with WFPC2 in the F702W filter, and the spectroscopic sample is statistically complete to Mr~-19.0+5logh, within an 11' (~1.8h^-1^Mpc) field. The clusters are dynamically well-separated from the surrounding field and most have velocity distributions consistent with Gaussians. The velocity dispersions range from 350-850km/s, consistent with the local L_X_-{sigma} correlation. All 10 clusters host a bright, giant elliptical galaxy without emission lines, near the centre of the X-ray emission. We measure the equivalent width of two nebular emission lines, [O II] and H{alpha}, and the H{delta} absorption line to classify the cluster members spectrally. Galaxy morphologies are measured from the HST images, using the two-dimensional surface-brightness fitting software GIM2D.
- ID:
- ivo://CDS.VizieR/J/A+A/504/347
- Title:
- Galaxy properties in clusters
- Short Name:
- J/A+A/504/347
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the dependence of several galaxy properties on the environment and cluster identification techniques.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A85
- Title:
- Galaxy properties in clusters. II.
- Short Name:
- J/A+A/564/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the properties of galaxies on the outskirts of clusters and their dependence on recent dynamical history in order to understand the real impact that the cluster core has on the evolution of galaxies. We analyse the properties of more than 1000 galaxies brighter than M_r_^0.1^=-19.6 on the outskirts of 90 clusters (1<r/r_vir_<2) in the redshift range 0.05<z<0.10. Using the line of sight velocity of galaxies relative to the cluster's mean, we selected low and high velocity subsamples. Theoretical predictions indicate that a significant fraction of the first subsample should be backsplash galaxies, that is, objects that have already orbited near the cluster centre. A significant proportion of the sample of high relative velocity (HV) galaxies seems to be composed of infalling objects. Our results suggest that, at fixed stellar mass, late-type galaxies in the low-velocity (LV) sample are systematically older, redder, and have formed fewer stars during the last 3Gyrs than galaxies in the HV sample. This result is consistent with models that assume that the central regions of clusters are effective in quenching the star formation by means of processes such as ram pressure stripping or strangulation. At fixed stellar mass, LV galaxies show some evidence of having higher surface brightness and smaller size than HV galaxies. These results are consistent with the scenario where galaxies that have orbited the central regions of clusters are more likely to suffer tidal effects, producing loss of mass as well as a re-distribution of matter towards more compact configurations. Finally, we found a higher fraction of ET galaxies in the LV sample, supporting the idea that the central region of clusters of galaxies may contribute to the transformation of morphological types towards earlier types.
- ID:
- ivo://CDS.VizieR/J/A+A/374/394
- Title:
- Gas and stars kinematics in disc galaxies
- Short Name:
- J/A+A/374/394
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ionized gas and stellar kinematical parameters have been measured along the major axis of 20 nearby disc galaxies. We discuss the properties of each sample galaxy, distinguishing between those characterized by regular or peculiar kinematics. In early-type disc galaxies, ionized gas tends to rotate faster than stars and to have a lower velocity dispersion (V_g_>V_*_ and {sigma}_g_<{sigma}_*_), whereas in late-type spirals, gas and stars show almost the same rotation velocities and velocity dispersions (V_g_=~V_*_ and {sigma}_g_=~{sigma}_*_). Incorporating the early-type disc galaxies studied by Bertola et al. (1995ApJ...448L..13B), Fisher (1997, Cat. <J/AJ/113/950>) and Corsini et al. (1999, Cat. <J/A+A/342/671>), we have compiled a sample of some 40 galaxies for which the major-axis radial profiles of both the stellar and gaseous components have been measured. The value of {sigma}_*_ measured at R_e_/4 turns out to be strongly correlated with the galaxy morphological type, while {sigma}_g_ is not and sometimes takes values above the range expected from thermal motions or small-scale turbulence.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/13
- Title:
- GASP. XXI. Star forming rate in 54 galaxies
- Short Name:
- J/ApJ/899/13
- Date:
- 15 Mar 2022 08:27:30
- Publisher:
- CDS
- Description:
- Using MUSE observations from the GASP survey, we study 54 galaxies undergoing ram pressure stripping (RPS) and spanning a wide range in galaxy mass and host cluster mass. We use this rich sample to study how the star formation rate (SFR) in the tails of stripped gas depends on the properties of the galaxy and its host cluster. We show that the interplay between all the parameters involved is complex and that there is not a single, dominant one in shaping the observed amount of SFR. Hence, we develop a simple analytical approach to describe the mass fraction of stripped gas and the SFR in the tail, as a function of the cluster velocity dispersion, galaxy stellar mass, clustercentric distance, and speed in the intracluster medium. Our model provides a good description of the observed gas truncation radius and of the fraction of SFR observed in the stripped tails, once we take into account the fact that the star formation efficiency in the tails is a factor of ~5 lower than in the galaxy disk, in agreement with GASP ongoing HI and CO observations. Finally, we estimate the contribution of RPS to the intracluster light (ICL) and find that the average SFR in the tails of ram pressure stripped gas is ~0.22M{odot}/yr per cluster. By extrapolating this result to evaluate the contribution to the ICL at different epochs, we compute an integrated average value per cluster of ~4x109M{sun} of stars formed in the tails of RPS galaxies since z~1.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A14
- Title:
- GaussPy+ decomposition of Galactic Ring Survey
- Short Name:
- J/A+A/633/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of large molecular line surveys of the Galactic plane is essential for our understanding of the gas kinematics on Galactic scales and, in particular, its link with the formation and evolution of dense structures in the interstellar medium. An approximation of the emission peaks with Gaussian functions allows for an efficient and straightforward extraction of useful physical information contained in the shape and Doppler-shifted frequency of the emission lines contained in these enormous data sets. In this work, we present an overview and the first results of a Gaussian decomposition of the entire Galactic Ring Survey (GRS) ^13^CO (1-0) data that consists of about 2.3 million spectra. We performed the decomposition with the fully automated GaussPy+ algorithm and fitted about 4.6 million Gaussian components to the GRS spectra. These decomposition results enable novel and unexplored ways to interpret and study the gas velocity structure. We discuss the statistics of the fit components and relations between the fitted intensities, velocity centroids, and velocity dispersions. We find that the magnitude of the velocity dispersion values increase towards the inner Galaxy and around the Galactic midplane, which we speculate is partly due to the influence of the Galactic bar and regions with higher non-thermal motions located in the midplane, respectively. We also used our decomposition results to infer global properties of the gas emission and find that the number of fit components used per spectrum is indicative of the amount of structure along the line of sight. We find that the emission lines from regions located on the far side of the Galaxy show increased velocity dispersion values, which are likely due to beam averaging effects. We demonstrate how this trend has the potential to aid in characterising Galactic structure by disentangling emission that belongs to the nearby Aquila Rift molecular cloud from emission that is more likely associated with the Perseus and Outer spiral arms. With this work, we also make our entire decomposition results available.
- ID:
- ivo://CDS.VizieR/J/AJ/153/114
- Title:
- GCs in 27 nearby ETGs from the SLUGGS survey
- Short Name:
- J/AJ/153/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Here, we present positions and radial velocities for over 4000 globular clusters (GCs) in 27 nearby early-type galaxies from the SLUGGS survey. The SLUGGS survey is designed to be representative of elliptical and lenticular galaxies in the stellar mass range 10<logM_*_/M_{sun}_<11.7. The data have been obtained over many years, mostly using the very stable multi-object spectrograph DEIMOS on the Keck II 10 m telescope. Radial velocities are measured using the calcium triplet lines, with a velocity accuracy of +/-10-15 km/s. We use phase space diagrams (i.e., velocity-position diagrams) to identify contaminants such as foreground stars and background galaxies, and to show that the contribution of GCs from neighboring galaxies is generally insignificant. Likely ultra-compact dwarfs are tabulated separately. We find that the mean velocity of the GC system is close to that of the host galaxy systemic velocity, indicating that the GC system is in overall dynamical equilibrium within the galaxy potential. We also find that the GC system velocity dispersion scales with host galaxy stellar mass, in a similar manner to the Faber-Jackson relation for the stellar velocity dispersion. Publication of these GC radial velocity catalogs should enable further studies in many areas, such as GC system substructure, kinematics, and host galaxy mass measurements.
- 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.
- 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].
