- 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.
Number of results to display per page
Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/153/220
- Title:
- NORAS II. I. First results
- Short Name:
- J/AJ/153/220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As the largest, clearly defined building blocks of our universe, galaxy clusters are interesting astrophysical laboratories and important probes for cosmology. X-ray surveys for galaxy clusters provide one of the best ways to characterize the population of galaxy clusters. We provide a description of the construction of the NORAS II galaxy cluster survey based on X-ray data from the northern part of the ROSAT All-Sky Survey. NORAS II extends the NORAS survey down to a flux limit of 1.8x10^-12^erg/s/cm^2^ (0.1-2.4keV), increasing the sample size by about a factor of two. The NORAS II cluster survey now reaches the same quality and depth as its counterpart, the southern REFLEX II survey, allowing us to combine the two complementary surveys. The paper provides information on the determination of the cluster X-ray parameters, the identification process of the X-ray sources, the statistics of the survey, and the construction of the survey selection function, which we provide in numerical format. Currently NORAS II contains 860 clusters with a median redshift of z=0.102. We provide a number of statistical functions, including the log N-log S and the X-ray luminosity function and compare these to the results from the complementary REFLEX II survey. Using the NORAS II sample to constrain the cosmological parameters, {sigma}_8_ and {Omega}_m_, yields results perfectly consistent with those of REFLEX II. Overall, the results show that the two hemisphere samples, NORAS II and REFLEX II, can be combined without problems into an all-sky sample, just excluding the zone of avoidance.
- ID:
- ivo://CDS.VizieR/J/AJ/125/2064
- Title:
- Northern Optical Cluster Survey. II.
- Short Name:
- J/AJ/125/2064
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new, objectively defined catalog of candidate galaxy clusters based on the galaxy catalogs from the digitized Second Palomar Observatory Sky Survey. This cluster catalog, derived from the best calibrated plates in the high-latitude (|b|>30{deg}) northern Galactic cap region, covers 5800deg^2^ and contains 8155 candidate clusters. A simple adaptive kernel density mapping technique, combined with the SExtractor object detection algorithm, is used to detect galaxy overdensities, which we identify as clusters. Simulations of the background galaxy distribution and clusters of varying richnesses and redshifts allow us to optimize detection parameters and measure the completeness and contamination rates for our catalog. Cluster richnesses and photometric redshifts are measured, using integrated colors and magnitudes for each cluster. An extensive spectroscopic survey is used to confirm the photometric results. This catalog, with well-characterized sample properties, provides a sound basis for future studies of cluster physics and large-scale structure.
- ID:
- ivo://CDS.VizieR/J/AJ/137/2981
- Title:
- Northern Optical Cluster Survey. III.
- Short Name:
- J/AJ/137/2981
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z<~0.25 drawn from the Digitized Second Palomar Observatory Sky Survey (DPOSS). The data presented here cover the Southern Galactic Cap, as well as the less well-calibrated regions of the Northern Galactic Cap. In addition, due to improvements in our cluster finder and measurement methods, we provide an updated catalog for the well-calibrated Northern Galactic Cap region previously published in Paper II (Cat. J/AJ/125/2064). The complete survey covers 11411deg^2^, with over 15000 candidate clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1017
- Title:
- Northern Optical Cluster Survey. IV.
- Short Name:
- J/AJ/128/1017
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optically selected galaxy cluster catalog from 2700{deg}^2^ of the digitized Second Palomar Observatory Sky Survey (DPOSS), spanning the redshift range 0.1~<z~<0.5, providing an intermediate-redshift supplement to the previous DPOSS cluster survey. This new catalog contains 9956 cluster candidates and is the largest resource of rich clusters in this redshift range to date.
