- ID:
- ivo://CDS.VizieR/J/ApJ/829/44
- Title:
- NGVS. XX. RedGOLD background galaxy clusters
- Short Name:
- J/ApJ/829/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We build a background cluster candidate catalog from the Next Generation Virgo Cluster Survey (NGVS) using our detection algorithm RedGOLD. The NGVS covers 104deg^2^ of the Virgo cluster in the u^*^,g,r,i,z-bandpasses to a depth of g~25.7mag (5{sigma}). Part of the survey was not covered or has shallow observations in the r band. We build two cluster catalogs: one using all bandpasses, for the fields with deep r-band observations (~20deg^2^), and the other using four bandpasses (u^*^,g,i,z) for the entire NGVS area. Based on our previous Canada-France-Hawaii Telescope Legacy Survey W1 studies, we estimate that both of our catalogs are ~100% (~70%) complete and ~80% pure, at z<=0.6 (z<~1), for galaxy clusters with masses of M>~10^14^M_{sun}_. We show that when using four bandpasses, though the photometric redshift accuracy is lower, RedGOLD detects massive galaxy clusters up to z~1 with completeness and purity similar to the five-band case. This is achieved when taking into account the bias in the richness estimation, which is ~40% lower at 0.5<=z<0.6 and ~20% higher at 0.6<z<0.8, with respect to the five-band case. RedGOLD recovers all the X-ray clusters in the area with mass M_500_>1.4x10^14^M_{sun}_ and 0.08<z<0.5. Because of our different cluster richness limits and the NGVS depth, our catalogs reach lower masses than the published redMaPPer cluster catalog over the area, and we recover ~90%-100% of its detections.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/227/12
- Title:
- NGVS XXV. Virgo globular clusters photometry
- Short Name:
- J/ApJS/227/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central region of the Virgo cluster of galaxies contains thousands of globular clusters (GCs), an order of magnitude more than the numbers found in the Local Group. Relics of early star formation epochs in the universe, these GCs also provide ideal targets to test our understanding of the Spectral Energy Distributions (SEDs) of old stellar populations. Based on photometric data from the Next Generation Virgo cluster Survey (NGVS) and its near-infrared counterpart NGVS-IR, we select a robust sample of ~2000 GCs with excellent photometry and spanning the full range of colors present in the Virgo core. The selection exploits the well defined locus of GCs in the uiK diagram and the fact that the globular clusters are marginally resolved in the images. We show that the GCs define a narrow sequence in 5-dimensional color space, with limited but real dispersion around the mean sequence. The comparison of these SEDs with the predictions of eleven widely used population synthesis models highlights differences between models, and also shows that no single model adequately matches the data in all colors. We discuss possible causes for some of these discrepancies. Forthcoming papers of this series will examine how best to estimate photometric metallicities in this context, and compare the Virgo globular cluster colors with those in other environments.
- ID:
- ivo://CDS.VizieR/J/ApJS/250/17
- Title:
- NGVS. XXXIV. Ultracompact dwarf galaxies in Virgo
- Short Name:
- J/ApJS/250/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of ultracompact dwarf (UCD) galaxies in the Virgo cluster based mainly on imaging from the Next Generation Virgo Cluster Survey (NGVS). Using ~100deg^2^ of u*giz imaging, we have identified more than 600 candidate UCDs, from the core of Virgo out to its virial radius. Candidates have been selected through a combination of magnitudes, ellipticities, colors, surface brightnesses, half-light radii, and, when available, radial velocities. Candidates were also visually validated from deep NGVS images. Subsamples of varying completeness and purity have been defined to explore the properties of UCDs and compare to those of globular clusters and the nuclei of dwarf galaxies with the aim of delineating the nature and origins of UCDs. From a surface density map, we find the UCDs to be mostly concentrated within Virgo's main subclusters, around its brightest galaxies. We identify several subsamples of UCDs-i.e., the brightest, largest, and those with the most pronounced and/or asymmetric envelopes-that could hold clues to the origin of UCDs and possible evolutionary links with dwarf nuclei. We find some evidence for such a connection from the existence of diffuse envelopes around some UCDs and comparisons of radial distributions of UCDs and nucleated galaxies within the cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A12
- Title:
- NIKA maps of ClG J1226.9+3332 at 150 and 250GHz
- Short Name:
- J/A+A/576/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The thermal Sunyaev-Zel'Dovich (tSZ) effect is expected to provide a low scatter mass proxy for galaxy clusters since it is directly proportional to the cluster thermal energy. The tSZ observations have proven to be a powerful tool for detecting and studying them, but high angular resolution observations are now needed to push their investigation to a higher redshift. In this paper, we report high angular (<20-arcsec) resolution tSZ observations of the high-redshift cluster CL J1226.9+3332 (z=0.89). It was imaged at 150 and 260GHz using the NIKA camera at the IRAM 30-meter telescope. The 150GHz map shows that CL J1226.9+3332 is morphologically relaxed on large scales with evidence of a disturbed core, while the 260GHz channel is used mostly to identify point source contamination. NIKA data are combined with those of Planck and X-ray from Chandra to infer the cluster's radial pressure, density, temperature, and entropy distributions. The total mass profile of the cluster is derived, and we find M_500_=5.96^+1.02^_-0.79_x10^14^M_{sun} within the radius R_500_=930^+50^_-43kpc, at a 68% confidence level. (R_500_ is the radius within which the average density is 500 times the critical density at the cluster's redshift.) NIKA is the prototype camera of NIKA2, a KIDs (kinetic inductance detectors) based instrument to be installed at the end of 2015. This work is, therefore, part of a pilot study aiming at optimizing tSZ NIKA2 large programs.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A118
- Title:
- NIKA Sunyaev-Zel'dovich data release
- Short Name:
- J/A+A/614/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Substructures in the hot gas atmosphere of galaxy clusters are related to their formation history and to the astrophysical processes at play in the intracluster medium (ICM). The thermal Sunyaev-Zel'dovich (tSZ) effect is directly sensitive to the line-of-sight integrated ICM pressure, and is thus particularly adapted to study ICM substructures. In this paper, we apply structure-enhancement filtering algorithms to high-resolution tSZ observations (e.g., NIKA) of distant clusters in order to search for pressure discontinuities, compressions, and secondary peaks in the ICM. The same filters are applied to toy-model images and to synthetic tSZ images extracted from RHAPSODY-G cosmological hydrodynamic simulations, in order to better interpret the extracted features. We also study the noise propagation through the filters and quantify the impact of systematic effects, such as data-processing-induced artifacts and point-source residuals, the latter being identified as the dominant potential contaminant. In three of our six NIKA-observed clusters we identify features at high signal-to-noise ratio that show clear evidence for merger events. In MACS J0717.5+3745 (z=0.55), three strong pressure gradients are observed on the east, southeast, and west sectors, and two main peaks in the pressure distribution are identified. We observe a lack of tSZ compact structure in the cool-core cluster PSZ1 G045.85+57.71 (z=0.61), and a tSZ gradient ridge dominates in the southeast. In the highest redshift cluster, CL J1226.9+3332 (z=0.89), we detect a ridge pressure gradient of ~45-arcsec (360kpc) in length associated with a secondary pressure peak in the west region. Our results show that current tSZ facilities have now reached the angular resolution and sensitivity to allow an exploration of the details of pressure substructures in clusters, even at high redshift. This opens the possibility to quantify the impact of the dynamical state on the relation between the tSZ signal and the mass of clusters, which is important when using tSZ clusters to test cosmological models. This work also marks the first NIKA cluster sample data release.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/22
- Title:
- NIR galaxy cluster candidates in the SPT survey
- Short Name:
- J/ApJ/761/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the ground- and space-based optical and near-infrared (NIR) follow-up of 224 galaxy cluster candidates detected with the Sunyaev-Zel'dovich (SZ) effect in the 720deg^2^ of the South Pole Telescope (SPT) survey completed in the 2008 and 2009 observing seasons. We use the optical/NIR data to establish whether each candidate is associated with an overdensity of galaxies and to estimate the cluster redshift. Most photometric redshifts are derived through a combination of three different cluster redshift estimators using red-sequence galaxies, resulting in an accuracy of {Delta}z/(1+z)=0.017, determined through comparison with a subsample of 57 clusters for which we have spectroscopic redshifts. We successfully measure redshifts for 158 systems and present redshift lower limits for the remaining candidates. The redshift distribution of the confirmed clusters extends to z=1.35 with a median of z_med_=0.57. Approximately 18% of the sample with measured redshifts lies at z>0.8. We estimate a lower limit to the purity of this SPT SZ-selected sample by assuming that all unconfirmed clusters are noise fluctuations in the SPT data. We show that the cumulative purity at detection significance {xi}>5 ({xi}>4.5) is >=95% (>=70%). We present the red brightest cluster galaxy (rBCG) positions for the sample and examine the offsets between the SPT candidate position and the rBCG. The radial distribution of offsets is similar to that seen in X-ray-selected cluster samples, providing no evidence that SZ-selected cluster samples include a different fraction of recent mergers from X-ray-selected cluster samples.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/2367
- Title:
- NIR Ks photometry of Norma cluster (A3627)
- Short Name:
- J/MNRAS/396/2367
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A deep Ks-band photometric catalogue of galaxies at the core of the rich, nearby Norma cluster (ACO3627) is presented. The survey covers about 45x45arcmin^2^ (slightly less than 1/3 Abell radius), which corresponds to ~0.8h_70_^-2^Mpc^2^ at the adopted distance (v_CMB_/H_0_) of 70h_70_^-1^Mpc of this cluster. The survey is estimated to be complete to a magnitude of M_Ks_<~-19.5mag. This extends into the dwarf regime, 6mag below M*_Ks_. The catalogue contains 390 objects, 235 of which are classified as likely or definite galaxies and 155 as candidate galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/1502
- Title:
- NIR photometry of X-ray luminous BCGs
- Short Name:
- J/MNRAS/384/1502
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the near-infrared evolution of brightest cluster galaxies (BCGs) from a sample of rich galaxy clusters since z~1. By employing an X-ray selection of LX>10^44^erg/s, we limit environmental effects by selecting BCGs in comparably high-density regions. We find a positive relationship between X-ray and near-infrared luminosity for BCGs in clusters with LX>5x10^44^erg/s. Applying a correction for this relation, we reduce the scatter in the BCG absolute magnitude by a factor of 30 per cent. The near-infrared J-K colour evolution demonstrates that the stellar population in BCGs has been in place since at least z=2, and that we expect a shorter period of star formation than that predicted by current hierarchical merger models. We also confirm that there is a relationship between 'blue' J-K colour and the presence of BCG emission lines associated with star formation in cooling flows.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1558
- Title:
- NOAO Fundamental Plane Survey
- Short Name:
- J/AJ/128/1558
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We introduce the NOAO Fundamental Plane Survey (NFPS), a wide-field imaging/spectroscopic study of rich, low-redshift galaxy clusters. The survey targets X-ray-selected clusters at 0.010<z<0.067, distributed over the whole sky, with imaging and spectroscopic observations obtained for 93 clusters. This data set will be used in investigations of galaxy properties in the cluster environment and of large-scale velocity fields through the fundamental plane. In this paper, we present details of the cluster sample construction and the strategies employed to select early-type galaxy samples for spectroscopy. Details of the spectroscopic observations are reported. From observations of 5479 red galaxies, we present redshift measurements for 5388 objects and internal velocity dispersions for 4131. The velocity dispersions have a median estimated error ~7%. The NFPS has ~15% overlap with previously published velocity dispersion data sets. Comparisons to these external catalogs are presented and indicate typical external errors of ~8%.
- ID:
- ivo://CDS.VizieR/J/ApJS/129/435
- Title:
- NORAS galaxy cluster survey. I.
- Short Name:
- J/ApJS/129/435
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the construction of an X-ray-selected sample of galaxy clusters for cosmological studies, we have assembled a sample of 495 X-ray sources found to show extended X-ray emission in the first processing of the ROSAT All-Sky Survey. The sample covers the celestial region with declination {delta}>=0{deg} and Galactic latitude |b|>=20{deg} and comprises sources with a count rate >=0.06counts/s and a source extent likelihood of L>=7. In an optical follow-up identification program we find 378 (76%) of these sources to be clusters of galaxies.
