- ID:
- ivo://CDS.VizieR/J/A+AS/129/281
- Title:
- ABCG 85 velocities catalogue
- Short Name:
- J/A+AS/129/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of velocities for 551 galaxies (and give the coordinates of 39 stars misclassified as galaxies in our photometric plate catalogue) in a region covering about 100'x100' (0.94x0.94Mpc for an average redshift of 0.0555, assuming H_0_=50km/s/Mpc) in the direction of the rich cluster ABCG85. This catalogue includes previously published redshifts by Beers et al. (1991AJ....102.1581B) and Malumuth et al. (1992AJ....104..495M), together with our 367 new measurements. A total of 305 galaxies have velocities in the interval 13350-20000km/s, and will be considered as members of the cluster. ABCG 85 therefore becomes one of the clusters with the highest number of measured redshifts; its optical properties are being investigated in a companion paper.
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- ID:
- ivo://CDS.VizieR/J/A+A/641/A90
- Title:
- AB Dor A VLBI images
- Short Name:
- J/A+A/641/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fast rotator, pre-main sequence star AB Dor A is a strong and persistent radio emitter. The extraordinary coronal flaring activity is thought to be the origin of compact radio emission and other associated phenomena, such as large slingshot prominences. We aim to investigate the radio emission mechanism and the milliarcsecond radio structure around AB Dor A. We performed phase-referenced VLBI observations at 22.3GHz, 8.4GHz, and 1.4GHz over more than one decade using the Australian VLBI array. Our 8.4GHz images show a double core-halo morphology, similar at all epochs, with emission extending at heights between 5 and 18 stellar radii. Furthermore, the sequence of the 8.4GHz maps shows a clear variation of the source structure within the observing time. However, images at 1.4GHz and 22.3GHz are compatible with a compact source. The phase-reference position at 8.4GHz and 1.4GHz are coincident with those expected from the well-known milliarcsecond-precise astrometry of this star, meanwhile the 22.3GHz position is 4sigma off the prediction in the north-west direction. The origin of this offset is still unclear. We have considered several models to explain the morphology and evolution of the inner radio structure detected in AB Dor A. These models include emission from the stellar polar caps, a flaring, magnetically-driven loop structure, and the presence of helmet streamers. We also investigated a possible close companion to AB Dor A. Our results confirm the extraordinary coronal magnetic activity of this star, capable of producing compact radio structures at very large heights that have so far only been seen in binary interacting systems.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A3
- Title:
- Abell 3391-Abell 3395 ASKAP/EMU image
- Short Name:
- J/A+A/647/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The pre-merging system of galaxy clusters Abell 3391-Abell 3395 located at a mean redshift of 0.053 has been observed at 1GHz in an ASKAP/EMU Early Science observation as well as in X-rays with eROSITA. The projected separation of the X-ray peaks of the two clusters is ~50{deg} or ~3.1Mpc. Here we present an inventory of interesting radio sources in this field around this cluster merger. While the eROSITA observations provide clear indications of a bridge of thermal gas between the clusters, neither ASKAP nor MWA observations show any diffuse radio emission coinciding with the X-ray bridge. We derive an upper limit on the radio emissivity in the bridge region of <J>_1GHz_<1.2x10^-44^W/H/m3. A non-detection of diffuse radio emission in the X-ray bridge between these two clusters has implications for particle-acceleration mechanisms in cosmological large-scale structure. We also report extended or otherwise noteworthy radio sources in the 30deg^2^ field around Abell 3391-Abell 3395. We identified 20 Giant Radio Galaxies, plus 7 candidates, with linear projected sizes greater than 1Mpc. The sky density of field radio galaxies with largest linear sizes of >0.7Mpc is ~1.7deg^2^, three times higher than previously reported. We find no evidence for a cosmological evolution of the population of Giant Radio Galaxies. Moreover, we find seven candidates for cluster radio relics and radio halos.
- ID:
- ivo://CDS.VizieR/J/A+A/588/A105
- Title:
- Abell 983 and Abell 1731 NIR fluxes
- Short Name:
- J/A+A/588/A105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of star formation and central black hole accretion activity of galaxies that are hosted in the two nearby (z~0.2) rich galaxy clusters Abell 983 and 1731. We aim to quantify both the obscured and unobscured star formation rates, as well as the presence of active galactic nuclei (AGN) as a function of the environment in which the galaxy is located. We targeted the clusters with unprecedented deep infrared Spitzer observations (0.2mJy @ 24-micron), near-IR Palomar imaging and optical WIYN spectroscopy. The extent of our observations (~3 virial radii) covers the vast of possible environments, from the very dense cluster centre to the very rarefied cluster outskirts and accretion regions. The star-forming members of the two clusters present star formation rates that are comparable with those measured in coeval field galaxies. Analysis of the spatial arrangement of the spectroscopically confirmed members reveals an elongated distribution for A1731 with respect to the more uniform distribution of A983. The emerging picture is compatible with A983 being a fully evolved cluster, in contrast with the still actively accreting A1731. Analysis of the specific star formation rate reveals evidence of ongoing galaxy pre-processing along A1731's filament-like structure. Furthermore, the decrease in the number of star-forming galaxies and AGN towards the cluster cores suggests that the cluster environment is accelerating the ageing process of the galaxies and blocking further accretion of the cold gas that fuels both star formation and black hole accretion activity.
- ID:
- ivo://CDS.VizieR/J/ApJ/693/152
- Title:
- Abell 851 and the role of starbursts
- Short Name:
- J/ApJ/693/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use extensive new observations of the very rich z~0.4 cluster of galaxies A851 (Cl 0939+47) to examine the nature and origin of starburst galaxies in intermediate-redshift clusters. New HST observations, 24um Spitzer photometry and ground-based spectroscopy cover most of a region of the cluster about 10' across, corresponding to a cluster-centric radial distance of about 1.6Mpc. This spatial coverage allows us to confirm the existence of a morphology-density relation within this cluster, and to identify several large, presumably infalling, subsystems. We confirm our previous conclusion that a very large fraction of the star-forming galaxies in A851 has recently undergone starbursts. We argue that starbursts are mostly confined to two kinds of sites: infalling groups and the cluster center.
- ID:
- ivo://CDS.VizieR/VII/4A
- Title:
- Abell and Zwicky Clusters of Galaxies
- Short Name:
- VII/4A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- See the complete documentation written by Robert S. Hill (file adc.doc)
- ID:
- ivo://CDS.VizieR/J/MNRAS/211/637
- Title:
- Abell 85 CCD observations
- Short Name:
- J/MNRAS/211/637
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A CCD camera survey has been conducted of the X-ray emitting regions of a sample of clusters of galaxies. This sample includes at least one cluster from each of the classes in the new Forman-Jones classification scheme (Forman & Jones 1982ARA&A..20..547F). In this paper, the techniques used to obtain, reduce and analyse the data are presented, along with results for the cluster Abell 85. For the central X-ray emitting region of this cluster, a core radius of between 1.2 and 1.6Mpc is estimated from the galaxy radial number density distribution. The properties of the galaxies in the core of this cluster are significantly different from those of the galaxies in the outer regions of the area covered in the survey, in terms of luminosity function and colour distribution.
- ID:
- ivo://CDS.VizieR/J/ApJS/126/1
- Title:
- Abell clusters photometry
- Short Name:
- J/ApJS/126/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry of 209 southern Abell clusters selected according to Bautz-Morgan type I, III, and II. We have performed total photometry in the Gunn r bandpass, classified stars and galaxies, and obtained structural parameters for the images. To estimate the photometric and structural errors on the CCD images and the completeness limits of our photometry, we performed realistic simulations of stars and galaxies and ran our classification algorithms. Here, we present central galaxy counts and metric photometry of the brightest cluster members, for which we give accurate positions, and compare this photometry with values in the literature. A linear magnitude-redshift relation has been derived from the tenth-ranked galaxy in each cluster. Photometric redshifts have been estimated for 57 clusters. We provide either spectroscopic or photometric redshifts for all the clusters in our sample. Further analysis of these data will be presented in further publications.
- ID:
- ivo://CDS.VizieR/J/AJ/118/1468
- Title:
- 35 Abell clusters Tully-Fisher observations
- Short Name:
- J/AJ/118/1468
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Tully-Fisher observations for 35 rich Abell clusters of galaxies. Results from I-band photometry and optical rotation curve work constitute the bulk of this paper. This is the third such data installment of an all-sky survey of 52 clusters in the distance range ~50 to 200h^-1^Mpc. The complete data set provides the basis for determining an accurate Tully-Fisher template relation and for estimating the amplitude and direction of the local bulk flow on a 100h^-1^Mpc scale
- ID:
- ivo://CDS.VizieR/J/ApJ/470/724
- Title:
- Abell 576 galaxies magnitude and velocities
- Short Name:
- J/ApJ/470/724
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse the galaxy population and dynamics of the galaxy cluster A576; the observational constraints include 281 redshifts (230 new), R-band CCD galaxy photometry over a 2h^-1^Mpcx2h^-1^Mpc region centered on the cluster, an Einstein IPC X-ray image, and an Einstein MPC X-ray spectrum. We focus on an 86% complete magnitude-limited sample (R_23.5_<17) of 169 cluster galaxies. The cluster galaxies with emission lines in their spectra have a larger velocity dispersion and are significantly less clustered on this 2h^-1^Mpc scale than galaxies without emission lines. We show that excluding the emission-line galaxies from the cluster sample decreases the velocity dispersion by 18% and the virial mass estimate by a factor of 2. The central cluster region contains a non-emission galaxy population and an intracluster medium which is significantly cooler ({sigma}_core_=387^+250^_-105_km/s and T_X_=1.6-0.3/+0.4keV at 90% confidence) than the global populations ({sigma}=977^+124^_-96_km/s for the non-emission population and T_X_>4keV at 90% confidence). Because (1) the low-dispersion galaxy population is no more luminous than the global population and (2) the evidence for a cooling flow is weak, we suggest that the core of A576 may contain the remnants of a lower mass subcluster. We examine the cluster mass, baryon fraction, and luminosity function. The cluster virial mass varies significantly depending on the galaxy sample used. Consistency between the hydrostatic and virial estimators can be achieved if (1) the gas temperature at r~1h^-1^Mpc is T_X_~8keV (the best-fit value) and (2) several velocity outliers are excluded from the virial calculation. Although the best-fit Schechter function parameters and the ratio of galaxy to gas mass in A576 are typical of other clusters, the baryon fraction is relatively low. Using the consistent cluster binding mass, we show that the gas mass fraction is ~3h^-3/2^% and the baryon fraction is ~4%.
