- ID:
- ivo://CDS.VizieR/J/other/NewA/27.41
- Title:
- Velocity distributions in galaxy clusters
- Short Name:
- J/other/NewA/27.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study 416 galaxy systems with more than 7 members selected from the 2MASS catalog. We applied five well known normality tests to the velocity distributions of these systems to distinguish Gaussian and non-Gaussian clusters. Using controlled samples, we estimated type I and II errors for each test. We verified that individual tests minimize the chances of classifying a Gaussian system as non-Gaussian, while the Fisher's meta-analysis method, a procedure to combine p-values from several statistical tests, minimizes the chances of classifying a non-Gaussian system as Gaussian. Taking the positive elements of each method and also including a modality analysis of the velocity distribution, we defined objective criteria to split up the sample into Gaussian and non-Gaussian clusters. Our analysis indicates that 50-58% of groups have Gaussian distribution, a lower fraction than that we found using individual normality tests, 71-87%. We also found that some properties of galaxy clusters are significantly different between Gaussian and non-Gaussian systems. For instance, non-Gaussian clusters have larger radii and contain more galaxies than Gaussian clusters. Finally, we discussed the importance of choosing the adequate methodology to classify galaxy systems from their velocity distributions and also the dependence of the results on the criteria used to identify clusters in galaxy surveys.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/633/A108
- Title:
- Velocity field of the Lyra complex
- Short Name:
- J/A+A/633/A108
- Date:
- 02 Nov 2021 11:15:00
- Publisher:
- CDS
- Description:
- The formation of cosmic structures culminates with the assembly of galaxy clusters, a process that is quite different from cluster to cluster. We present the study of the structure and dynamics of the Lyra complex, consisting of the two clusters RXC J1825.3+3026 and CIZA J1824.1+3029, which was very recently studied by using both X-ray and radio data. This is the first analysis based on the kinematics of member galaxies. New spectroscopic data for 285 galaxies were acquired at the Italian Telescopio Nazionale Galileo and were used in combination with PanSTARRS photometry. The result of our member selection is a sample of 198 galaxies. For RXCJ1825 and CIZAJ1824 we report the redshifts, z=0.0645 and z=0.0708, the first estimates of velocity dispersion, sigma_v_=995_-125_^+131^km/s and sigma_v_=700+/-50km/s, and of dynamical mass, M_200_=1.1+/-0.4x10^15^M_[sun}_ and M_200_=4+/-0.110^14^M_{sun}_. The past assembly of RXCJ1825 is traced by the two dominant galaxies, which are both aligned with the major axis of the galaxy distribution along the east-west direction, and by a minor northeast substructure. We also detect a quite peculiar high velocity field in the southwest region of the Lyra complex. This feature is likely related to a very luminous galaxy, which is characterized by a high velocity. This galaxy is suggested to be the central galaxy of a group that is in interaction with RXCJ1825 according to very recent studies based on X-ray and radio data. The redshift of the whole Lyra complex is z=0.067. Assuming that the redshift difference between RXCJ1825 and CIZAJ1824 is due to the relative kinematics, the projected distance between the cluster centers is D~1.3Mpc and the line-of-sight velocity difference is ~1750km/s. A dynamical analysis of the system shows that the two clusters are likely to be gravitationally bound in a pre-merger phase, and that CIZAJ1824 is moving toward RXCJ1825. Our results corroborate a picture where the Lyra region is the place of a very complex scenario of cluster assembly.
- ID:
- ivo://CDS.VizieR/J/ApJ/622/187
- Title:
- Velocity of eight RASSCALS galaxy groups
- Short Name:
- J/ApJ/622/187
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the distribution of gas pressure and entropy in eight groups of galaxies belonging to the ROSAT All-Sky Survey/Center for Astrophysics Loose Systems (RASSCALS, Cat. <J/ApJ/534/114>). We use archival and proprietary XMM-Newton observations, supplementing the X-ray data with redshifts derived from the literature; we also list 125 new redshifts measured with the Gemini North telescope.
- ID:
- ivo://CDS.VizieR/J/ApJS/146/267
- Title:
- Very rich Abell clusters radio analysis
- Short Name:
- J/ApJS/146/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio observations were used to detect the "active" galaxy population within rich clusters of galaxies in a nonbiased manner that is not plagued by dust extinction or the K-correction. We present wide-field radio, optical (imaging and spectroscopy), and ROSAT All-Sky Survey (RASS, Cat. <IX/10>) X-ray data for a sample of 30 very rich Abell (R>=2) cluster with z<=0.25. The VLA radio data samples the ultrafaint radio (L(1.4GHz)>=2x10^22^W/Hz) galaxy population within these extremely rich clusters for galaxies with RMAG<=-21. This is the largest sample of low-luminosity 20 cm radio galaxies within rich Abell clusters collected to date.
- ID:
- ivo://CDS.VizieR/J/A+A/444/685
- Title:
- VGCF detection of galaxy systems
- Short Name:
- J/A+A/444/685
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of the 48 Voronoi Galaxy Cluster Finder (VGCF) cluster detections. We provide a cluster ID, signal to noise ratios (SNR) in the B, V, R and I bands, positions, angular radius of the cluster, photometric redshift estimates (derived from color-magnitude diagrams (CMD)) and PDCS redshift estimate (Postman et al., 1996AJ....111..615P), if available. Table 5 contains cluster detections in F0028+0515, F0027+0555, F0228+0115 and F0226+0026 fields and other two regions that overlap PDCS 0h and 2h fields.
- ID:
- ivo://CDS.VizieR/J/ApJ/563/629
- Title:
- VIK' photometry and redshifts of galaxy clusters
- Short Name:
- J/ApJ/563/629
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze photometry and spectroscopy of a sample of 63 clusters at 0.3<=z<=0.9 drawn from the Las Campanas Distant Cluster Survey to empirically constrain models of cluster galaxy evolution. Our data originate from a variety of telescopes and instruments. The candidate galaxy clusters are identified using drift-scan images and techniques described briefly below for context but in full detail by Gonzalez et al. (2001, Cat. <J/ApJS/137/117>).
- ID:
- ivo://CDS.VizieR/J/ApJ/566/103
- Title:
- VIK' photometry and redshifts of galaxy clusters
- Short Name:
- J/ApJ/566/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the influence of environment on brightest cluster galaxy (BCG) evolution using a sample of 63 clusters at 0.3<=z<=0.9 drawn primarily from the Las Campanas Distant Cluster Survey and follow-up V, I, and K' photometry. Our data originate from a variety of telescopes and instruments. The cluster sample and observations used here stem from deep optical and infrared follow-up imaging of a small subset of the full catalog that was obtained to aid in the classification of candidates and to develop photometric redshift indicators.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/133
- Title:
- Virgo cluster ETGs: GC and galaxy diffuse light
- Short Name:
- J/ApJ/806/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a kinematic analysis of the globular cluster (GC) systems and diffuse stellar light of four intermediate luminosity (sub-L*) early-type galaxies in the Virgo cluster based on Gemini Multi-Object Spectrographs (GMOS) data. Our galaxy sample is fainter (-23.8<M_K_<-22.7) than most previous studies, nearly doubling the number of galaxies in this magnitude range that now have GC kinematics. The data for the diffuse light extends to 4R_e_, and the data for the GCs reaches 8-12R_e_. We find that the kinematics in these outer regions are all different despite the fact that these four galaxies have similar photometric properties, and are uniformly classified as "fast rotators" from their stellar kinematics within 1R_e_. The GC systems exhibit a wide range of kinematic morphology. The rotation axis and amplitude can change between the inner and outer regions, including a case of counter-rotation. This difference shows the importance of wide-field kinematic studies, and shows that stellar and GC kinematics can change significantly as one moves beyond the inner regions of galaxies. Moreover, the kinematics of the GC systems can differ from that of the stars, suggesting that the formation of the two populations are also distinct.
- ID:
- ivo://CDS.VizieR/J/A+A/343/86
- Title:
- Virgo cluster radio luminosity function. I.
- Short Name:
- J/A+A/343/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We cross-correlate the galaxies brighter than m_B_=18 in the Virgo cluster with the radio sources in the NVSS survey (1.4GHz), resulting in 180 radio-optical identifications. We determine the radio luminosity function of the Virgo galaxies, separately for the early- and late-types. Late-type galaxies develop radio sources with a probability proportional to their optical luminosity. In fact their radio/optical (R_B_) distribution is gaussian, centered at log R_B_~-0.5, i.e. the radio luminosity is ~0.3 of the optical one. The probability of late-type galaxies to develop radio sources is almost independent of their detailed Hubble type, except for Sa (and S0+S0a) which are a factor of ~5 less frequent than later types at any R_B_. Giant elliptical galaxies feed "monster" radio sources with a probability strongly increasing with mass. However the frequency of fainter radio sources is progressively less sensitive on the system mass. The faintest giant E galaxies (M_B_=-17) have a probability of feeding low power radio sources similar to that of dwarf E galaxies as faint as M_B_=-13.
- ID:
- ivo://CDS.VizieR/J/ApJS/111/143
- Title:
- Virgo cluster ultraviolet sources
- Short Name:
- J/ApJS/111/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze three UV images covering a ~100 square degree field toward the Virgo cluster, obtained by the FAUST space experiment. We detect 191 sources to a signal-to-noise ratio of 4.4 and identify 94% of them. Most sources have optical counterparts in existing catalogs, and about half are identified as galaxies. Some sources with no listed counterpart were observed at the Wise Observatory. We present the results of low-resolution visible spectrophotometry and discuss the foreground 101 stellar sources and the 76 detected galaxies, both in the cluster and in the foreground or background. We derive conclusions on star formation properties of galaxies and on the total UV flux from discrete and diffuse sources in the cluster. We test for the presence of intracluster dust, determine the clustering properties of UV emitting galaxies, and derive the UV luminosity function of Virgo galaxies.
