- ID:
- ivo://CDS.VizieR/J/ApJ/841/7
- Title:
- Spectroscopic obs & members of ZwCl 2341+0000
- Short Name:
- J/ApJ/841/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- ZwCl 2341.1+0000, a merging galaxy cluster with disturbed X-ray morphology and widely separated (~3Mpc) double radio relics, was thought to be an extremely massive (10-30x10^14^M_{sun}_) and complex system, with little known about its merger history. We present JVLA 2-4GHz observations of the cluster, along with new spectroscopy from our Keck/DEIMOS survey, and apply Gaussian Mixture Modeling to the three-dimensional distribution of 227 confirmed cluster galaxies. After adopting the Bayesian Information Criterion to avoid overfitting, which we discover can bias high the total dynamical mass estimates, we find that a three-substructure model with a total dynamical mass estimate of 9.39+/-0.81x10^14^M_{sun}_ is favored. We also present deep Subaru imaging and perform the first weak lensing analysis on this system, obtaining a weak lensing mass estimate of 5.57+/-2.47x10^14^M_{sun}_. This is a more robust estimate because it does not depend on the dynamical state of the system, which is disturbed due to the merger. Our results indicate that ZwCl2341.1+0000 is a multiple merger system comprised of at least three substructures, with the main merger that produced the radio relics occurring near the plane of the sky, and a younger merger in the north occurring closer to the line of sight. Dynamical modeling of the main merger reproduces observed quantities (relic positions and polarizations, subcluster separation and radial velocity difference), if the merger axis angle of ~10_-6_^+34^ degrees and the collision speed at pericenter is ~1900_-200_^+300^km/s.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/863/102
- Title:
- Spectroscopic redshift catalog in A2142 field
- Short Name:
- J/ApJ/863/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the dynamics of the galaxy cluster A2142, we compile an extended catalog of 2239 spectroscopic redshifts of sources, including 237 newly measured redshifts, within 30 arcmin from the cluster center. With the {sigma}-plateau algorithm from the caustic method, we identify 868 members and a number of substructures in the galaxy distribution both in the outskirts, out to ~3.5Mpc from the cluster center, and in the central region. In the outskirts, one substructure overlaps a falling clump of gas previously identified in the X-ray band. These substructures suggest the presence of multiple minor mergers, which are responsible for the complex dynamics of A2142, and the absence of recent or ongoing major mergers. We show that the distribution of the galaxies in the cluster core and in several substructures is consistent with the mass distribution inferred from the weak-lensing signal. Moreover, we use spatially resolved X-ray spectroscopy to measure the redshift of different regions of the intracluster medium within ~3 arcmin from the cluster center. We find a ring of gas near the two X-ray cold fronts identified in previous analyses and measure a velocity of this ring of 810+/-330km/s larger than the cluster mean velocity. Our analysis suggests the presence of another ring surrounding the core, whose velocity is 660+/-300km/s larger than the cluster velocity. These X-ray features are not associated with any optical substructures, and support the core-sloshing scenario suggested in previous work.
- ID:
- ivo://CDS.VizieR/J/ApJ/741/122
- Title:
- Spectroscopic redshifts in A2142 and RXJ1720.1+2638
- Short Name:
- J/ApJ/741/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present evidence for the existence of substructure in the "relaxed appearing" cold front clusters Abell 2142 and RXJ1720.1+2638. The detection of these substructures was made possible by comprehensive multi-object optical spectroscopy obtained with the Hectospec and DEep Imaging Multi-Object Spectrograph instruments on the 6.5m MMT and 10m Keck II telescope, respectively. These observations produced 956 and 400 spectroscopically confirmed cluster members within a projected radius of 3Mpc from the centers of A2142 and RXJ1720.1+2638, respectively. The substructure manifests itself as local peaks in the spatial distribution of member galaxies and also as regions of localized velocity substructure. For both Abell 2142 and RXJ1720.1+2638, we identify group-scale substructures which, when considering the morphology of the cold fronts and the time since pericentric passage of a perturber estimated from the cold front radii, could plausibly have perturbed the cluster cores and generated the cold fronts observed in Chandra images. The results presented here are consistent with cold fronts being the result of merger activity and with cold fronts in relaxed appearing clusters being due to minor merger activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/776/91
- Title:
- Spectroscopic redshifts of galaxies in 2 clusters
- Short Name:
- J/ApJ/776/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide a new observational test for a key prediction of the {Lambda}CDM cosmological model: the contributions of mergers with different halo-to-main-cluster mass ratios to cluster-sized halo growth. We perform this test by dynamically analyzing 7 galaxy clusters, spanning the redshift range 0.13<z_c_<0.45 and caustic mass range 0.4-1.5x10^15^h_0.73_^-1^M_{sun}_, with an average of 293 spectroscopically confirmed bound galaxies to each cluster. The large radial coverage (a few virial radii), which covers the whole infall region, with a high number of spectroscopically identified galaxies enables this new study. For each cluster, we identify bound galaxies. Out of these galaxies, we identify infalling and accreted halos and estimate their masses and their dynamical states. Using the estimated masses, we derive the contribution of different mass ratios to cluster-sized halo growth. For mass ratios between ~0.2 and ~0.7, we find a ~1{sigma} agreement with {Lambda}CDM expectations based on the Millennium simulations I and II. At low mass ratios, <~0.2, our derived contribution is underestimated since the detection efficiency decreases at low masses, ~2x10^14^h_0.73_^-1^M_{sun}_. At large mass ratios, >~0.7, we do not detect halos probably because our sample, which was chosen to be quite X-ray relaxed, is biased against large mass ratios. Therefore, at large mass ratios, the derived contribution is also underestimated.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/139
- Title:
- Spectroscopic redshifts of galaxies in groups
- Short Name:
- J/ApJ/756/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the global group properties of two samples of galaxy groups containing 39 high-quality X-ray-selected systems and 38 optically (spectroscopically) selected systems in coincident spatial regions at 0.12<z<0.79. The total mass range of the combined sample is ~(10^12^-5)x10^14^M_{sun}_. Only nine optical systems are associable with X-ray systems. We discuss the confusion inherent in the matching of both galaxies to extended X-ray emission and of X-ray emission to already identified optical systems. Extensive spectroscopy has been obtained and the resultant redshift catalog and group membership are provided here. X-ray, dynamical, and total stellar masses of the groups are also derived and presented. We explore the effects of utilizing different centers and applying three different kinds of radial cut to our systems: a constant cut of 1Mpc and two r_200_ cuts, one based on the velocity dispersion of the system and the other on the X-ray emission.
- ID:
- ivo://CDS.VizieR/J/ApJS/211/21
- Title:
- Spectroscopic redshifts of galaxies in MACS
- Short Name:
- J/ApJS/211/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 1921 spectroscopic redshifts measured in the fields of the massive galaxy clusters MACSJ0416.1-2403 (z=0.397), MACSJ0717.5+3745 (z=0.546), and MACSJ1149.5+2223 (z=0.544), i.e., three of the four clusters selected by Space Telescope Science Institute as the targets of the Frontier Fields (FFs) initiative for studies of the distant Universe via gravitational lensing. Compiled in the course of the Massive Cluster Survey project (MACS) that detected the FF clusters, this catalog is provided to the community for three purposes: (1) to allow the identification of cluster members for studies of the galaxy population of these extreme systems, (2) to facilitate the removal of unlensed galaxies and thus reduce shear dilution in weak-lensing analyses, and (3) to improve the calibration of photometric redshifts based on both ground- and spacebased observations of the FF clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/66
- Title:
- Spectroscopic redshifts of gal. in SPT-CLJ0615-5746
- Short Name:
- J/ApJ/878/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of spectroscopic redshifts for SPT-CLJ0615-5746, the most distant cluster in the Reionization Lensing Cluster Survey. Using Nod & Shuffle multislit observations with LDSS-3 on Magellan, we identify ~50 cluster members and derive a cluster redshift of z_c_=0.972, with a velocity dispersion of {sigma}=1244+/-162km/s. We calculate a cluster mass using a {sigma}_200_-M_200_ scaling relation of M_200_=(9.6+/-3.5)x10^14^M_{sun}_, in agreement with previous, independent mass measurements of this cluster. In addition, we examine the kinematic state of SPT-CLJ0615-5746, taking into consideration prior investigations of this system. With an elongated profile in lensing mass and X-ray emission, a non-Gaussian velocity dispersion that increases with clustercentric radius, and a brightest cluster galaxy not at rest with the bulk of the system, there are multiple cluster properties that, while not individually compelling, combine to paint a picture that SPT-CLJ0615-5746 is currently being assembled.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A31
- Title:
- Spectroscopic study of 283 AGNs in Coma
- Short Name:
- J/A+A/534/A31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma supercluster whose density spans two orders of magnitude from the sparse filaments to the cores of rich clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/378/1507
- Title:
- Spectroscopic study of 6 galaxies
- Short Name:
- J/MNRAS/378/1507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an examination of the kinematics and stellar populations of a sample of three brightest group galaxies (BGGs) and three brightest cluster galaxies (BCGs) in X-ray groups and clusters. We have obtained high signal-to-noise ratio Gemini/Gemini South Multi-Object Spectrograph (GMOS) long-slit spectra of these galaxies and use Lick indices to determine ages, metallicities and alpha-element abundance ratios out to at least their effective radii. We find that the BGGs and BCGs have very uniform masses, central ages and central metallicities.
- ID:
- ivo://CDS.VizieR/J/ApJS/137/279
- Title:
- Spectroscopic Survey in Coma
- Short Name:
- J/ApJS/137/279
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper in a series studying the photometric and spectroscopic properties of galaxies of different luminosities in the Coma Cluster. We present the sample selection, spectroscopic observations, and completeness functions. To study the spectral properties of galaxies as a function of their local environment, two fields were selected for spectroscopic observations to cover both the core (Coma 1) and outskirts (i.e., southwest of the core and centered on NGC 4839; Coma 3) of the cluster. To maximize the efficiency of spectroscopic observations, two subsamples were defined, consisting of "bright" and "faint" galaxies, both drawn from magnitude-limited parent samples. Medium-resolution spectroscopy (6-9{AA}) was then carried out for a total of 490 galaxies in both fields (302 in Coma 1 and 188 in Coma 3), using the WYFFOS multifiber spectrograph on the William Herschel Telescope. The galaxies cover a range of 12<R<20, corresponding to -23<M_R_<-15 (H_0_=65km/s/Mpc). The redshifts for these galaxies are measured with an accuracy of 75km/s.
