Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/151/78
- Title:
- Jellyfish galaxy candidates in galaxy clusters
- Short Name:
- J/AJ/151/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxies that are being stripped of their gas can sometimes be recognized from their optical appearance. Extreme examples of stripped galaxies are the so-called "jellyfish galaxies" that exhibit tentacles of debris material with a characteristic jellyfish morphology. We have conducted the first systematic search for galaxies that are being stripped of their gas at low-z (z=0.04-0.07) in different environments, selecting galaxies with varying degrees of morphological evidence for stripping. We have visually inspected B- and V-band images and identified 344 candidates in 71 galaxy clusters of the OMEGAWINGS+WINGS sample and 75 candidates in groups and lower mass structures in the PM2GC sample. We present the atlas of stripping candidates and a first analysis of their environment and their basic properties, such as morphologies, star formation rates and galaxy stellar masses. Candidates are found in all clusters and at all clustercentric radii, and their number does not correlate with the cluster velocity dispersion {sigma} or X-ray luminosity L_X_. Interestingly, convincing cases of candidates are also found in groups and lower mass halos (10^11^-10^14^M_{sun}_), although the physical mechanism at work needs to be securely identified. All the candidates are disky, have stellar masses ranging from log M/M_{sun}_<9 to >11.5 and the majority of them form stars at a rate that is on average a factor of 2 higher (2.5{sigma}) compared to non-stripped galaxies of similar mass. The few post-starburst and passive candidates have weak stripping evidence. We conclude that disturbed morphologies suggestive of stripping phenomena are ubiquitous in clusters and could be present even in groups and low mass halos. Further studies will reveal the physics of the gas stripping and clarify the mechanisms at work.
- ID:
- ivo://CDS.VizieR/J/A+A/640/A22
- Title:
- Jellyfish galaxy JO201 JVLA datacube
- Short Name:
- J/A+A/640/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HI observations of the jellyfish galaxy, JO201, a massive galaxy falling along the line-of-sight towards the centre of a rich cluster, A85 at a high velocity. Its H{alpha} emission shows a ~40kpc tail confined closely to its stellar disc and a ~100kpc tail extending further out. We find HI emission coinciding only with the shorter clumpy H{alpha} tail while no HI emission is detected along the ~100kpc Ha tail. In total, we measure an HI mass of M_HI_=1.65x10^+9^M_{sun}_, which is about 60% lower than expected based on its stellar mass and stellar surface density. We compared JO201 to another jellyfish in the GASP sample, JO206, and find that they are similarly HI-deficient. The global star formation rate (SFR) analysis of JO201 suggests that its observed SFR would be expected if it had 10x its current HI mass. The disc is the main contributor of the high star formation efficiency at a given HI gas density for both galaxies, but their tails also show higher star formation efficiencies compared to the outer regions of field galaxies. Generally, we find that JO201 and JO206 are similar based on their HI content, stellar mass and star formation rate. This finding is unexpected considering their different environments. A toy model comparing the ram pressure of the ICM versus the restoring forces of these galaxies suggests that the ram pressure strength exerted on them could be comparable if we consider their 3D orbital velocities and radial distances relative to the clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/112/2500
- Title:
- JHK' photometry of 4 clusters of galaxies
- Short Name:
- J/AJ/112/2500
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep near-infrared images of four intermediate redshift (z=0.2-0.4) clusters (Abell 370, Abell 963, CL 0024+1654 and CL 0909+4408) have been obtained in the J, H, and K bands using the UCLA Two-Channel IR Camera with a spatial resolution of ~1". The 3'x3' field of view includes over 100 galaxies in each cluster. Photometry has been obtained with 1{sigma} or limiting magnitudes of 21.7 at J, 21.0 at H, and 20.4 at K', and complete to 2 magnitudes fainter than L^*^. Data reduction techniques for flat-fielding object identification, and photometry of faint object crowded fields are discussed. The best method is the subtraction of a running-average sky made from object frames. The photometry is cross referenced to previous catalogs, and infrared color-magnitude diagrams are presented. Comparison of the IR colors of these four clusters to the predictions of the spectral synthesis models of Bruzual and Chariot is discussed. There is a discrepancy between the models and the observations of several tenths of a magnitude in the colors. Photometry has also been obtained for the gravitational lensing arcs in CL 0024+1654, which is consistent with an actively star-forming galaxy at z>1. For a description of the JHK' photometric system, see e.g. <GCPD/09>
- ID:
- ivo://CDS.VizieR/J/ApJS/237/14
- Title:
- KASI-Yonsei Deep Imaging Survey of Clusters (KYDISC)
- Short Name:
- J/ApJS/237/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the KASI-Yonsei Deep Imaging Survey of Clusters targeting 14 clusters at 0.015<~z<~0.144 using the Inamori Magellan Areal Camera and Spectrograph on the 6.5m Magellan Baade telescope and the MegaCam on the 3.6m Canada-France-Hawaii Telescope. We provide a catalog of cluster galaxies that lists magnitudes, redshifts, morphologies, bulge-to-total ratios, and local density. Based on the 1409 spectroscopically confirmed cluster galaxies brighter than -19.8 in the r band, we study galaxy morphology, color, and visual features generated by galaxy mergers. We see a clear trend between morphological content and cluster velocity dispersion, which was not presented by previous studies using local clusters. Passive spirals are preferentially found in a highly dense region (i.e., cluster center), indicating that they have gone through environmental quenching. In deep images ({mu}_r'_~27mag/arcsec^2^), 20% of our sample shows signatures of recent mergers, which is not expected from theoretical predictions and a low frequency of ongoing mergers in our sample (~4%). Such a high fraction of recent mergers in the cluster environment supports a scenario that the merger events that made the features have preceded the galaxy accretion into the cluster environment. We conclude that mergers affect a cluster population mainly through the preprocessing of recently accreted galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/56
- Title:
- K2-detected clusters in the CFHTLS-W1 field
- Short Name:
- J/ApJ/748/56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first weak gravitational lensing analysis of the completed Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). We study the 64 deg^2^ W1 field, the largest of the CFHTLS-Wide survey fields, and present the largest contiguous weak lensing convergence "mass map" yet made. 2.66 million galaxy shapes are measured, using the Kaiser Squires and Broadhurst Method (KSB) pipeline verified against high-resolution Hubble Space Telescope imaging that covers part of the CFHTLS. Our i'-band measurements are also consistent with an analysis of independent r'-band imaging. The reconstructed lensing convergence map contains 301 peaks with signal-to-noise ratio {nu}>3.5, consistent with predictions of a {Lambda}CDM model. Of these peaks, 126 lie within 3.0' of a brightest central galaxy identified from multicolor optical imaging in an independent, red sequence survey. We also identify seven counterparts for massive clusters previously seen in X-ray emission within 6 deg^2^ XMM-LSS survey. With photometric redshift estimates for the source galaxies, we use a tomographic lensing method to fit the redshift and mass of each convergence peak. Matching these to the optical observations, we confirm 85 groups/clusters with {chi}^2^_reduced_<3.0, at a mean redshift <z_c_>=0.36 and velocity dispersion <{sigma}_c_>=658.8km/s. Future surveys, such as DES, LSST, KDUST, and EUCLID, will be able to apply these techniques to map clusters in much larger volumes and thus tightly constrain cosmological models.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/251
- Title:
- Keck/LRIS confirmation of Coma membership
- Short Name:
- J/ApJ/723/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Keck/LRIS multi-object spectroscopy has been carried out on 140 of some of the lowest and highest surface brightness faint (19<R<22) dwarf galaxy candidates in the core region of the Coma Cluster. These spectra are used to measure redshifts and establish membership for these faint dwarf populations. The primary goal of the low surface brightness sample is to test our ability to use morphological and surface brightness criteria to distinguish between Coma Cluster members and background galaxies using high resolution Hubble Space Telescope/Advanced Camera for Surveys images. Candidates were rated as expected members, uncertain, or expected background. From 93 spectra, 51 dwarf galaxy members and 20 background galaxies are identified. Our morphological membership estimation success rate is ~100% for objects expected to be members and better than ~90% for galaxies expected to be in the background. We confirm that low surface brightness is a very good indicator of cluster membership. High surface brightness galaxies are almost always background with confusion arising only from the cases of the rare compact elliptical (cE) galaxies. The more problematic cases occur at intermediate surface brightness. Many of these galaxies are given uncertain membership ratings, and these were found to be members about half of the time. In a sample of 47 high surface brightness, ultracompact dwarf candidates, 19 objects have redshifts which place them in the Coma Cluster, while another 6 have questionable redshift measurements but may also prove to be members.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A114
- Title:
- Kinematic profiles of Virgo early-type galaxies
- Short Name:
- J/A+A/526/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new medium resolution kinematic data for a sample of 21 dwarf early-type galaxies (dEs) mainly in the Virgo cluster, obtained with the WHT and INT telescopes at the Roque de los Muchachos Observatory (La Palma, Spain). These data are used to study the origin of the dwarf elliptical galaxy population inhabiting clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/106/1273
- Title:
- Kinematics of dense clusters of galaxies
- Short Name:
- J/AJ/106/1273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured redshifts in the fields of the 31 R>=1 Abell clusters with 0.02<z<0.05 and |bII|>30{deg}, from medium resolution spectra (5 or 7{AA}). At least ten of the fields are severely contaminated by superimposed velocity peaks. We derive the mean velocities and velocity dispersions of the 25 dense peaks in the sample. The abundance of peaks, 6.6x10^-6^h^3^ Mpc^-3^, is consistent with the mean number density of R>1 Abell clusters (Bahcall & Soneira 1983ApJ...270...20B). The range of velocity dispersions is 304-1346 km/s. The median dispersion is 718 km/s. The subset of eight systems with cD galaxies has a median velocity dispersion of 792 km/s, close to that of non-cD systems (626 km/s). When these data are combined with 16 cD cluster velocity dispersions from our previous study (Zabludoff et al. 1990ApJS...74....1Z, and Dunn [Proceedings of NATO Conf. 1991]), eight of 25 cD galaxies have peculiar motions larger than half the cluster velocity dispersions. These findings further support the conclusions of Beers & Geller (1983ApJ...274..491B), and Dunn (1991), who argue that cD galaxies do not lie in the global kinematic center, but in local potential minima. If so, systems with speeding cD's are probably a guide to substructure in dynamically evolving systems.
- ID:
- ivo://CDS.VizieR/J/AJ/109/874
- Title:
- Kinematics of MKW and AWM Poor Clusters
- Short Name:
- J/AJ/109/874
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 472 new redshifts for 416 galaxies in the regions of the 23 poor clusters of galaxies originally identified by Morgan, Kayser, and White, and Albert, White and Morgan. Eighteen of the poor clusters now have 10 or more available redshifts within 1.5h^-1 Mpc of the central galaxy; 11 clusters have at least 20 available redshifts. Based on the 21 clusters for which we have sufficient velocity information, the median velocity scale is 336 km/s, a factor of 2 smaller than found for rich clusters. Several of the poor clusters exhibit complex velocity distributions due to the presence of nearby clumps of galaxies. We check on the velocity of the dominant galaxy in each poor cluster relative to the remaining cluster members. Significantly high relative velocities of the dominant galaxy are found in only 4 of 21 poor clusters, 3 of which we suspect are due to contamination of the parent velocity distribution. Several statistical tests indicate that the D/cD galaxies are at the kinematic centers of the parent poor cluster velocity distributions. Mass-to-light ratios for 13 of the 15 poor clusters for which we have the required data are in the range 50 <= M/L_B(0) <= 200 Msun/Lsun. The complex nature of the regions surrounding many of the poor clusters suggests that these groupings may represent an early epoch of cluster formation. For example, the poor clusters MKW7 and MKW8 are shown to be gravitationally bound and likely to merge to form a richer cluster within the next several Gyrs. Eight of the nine other poor clusters for which simple two-body dynamical models can be carried out are consistent with being bound to other clumps in their vicinity. Additional complex systems with more than two gravitationally bound clumps are observed among the poor clusters.
