- ID:
- ivo://CDS.VizieR/J/AJ/126/119
- Title:
- Optical and radio data for rich Abell clusters
- Short Name:
- J/AJ/126/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical observations and radio continuum imaging data for a sample of rich, X-ray-bright Abell clusters at intermediate (z~0.2) redshifts. We find that the radio galaxy population varies substantially from cluster to cluster within this homogeneous sample. The spatial distribution of the high-luminosity radio galaxies (HLRGs; L1.4>10^23^W/Hz) is very different from the low-luminosity radio galaxies (LLRGs; L1.4<=10^22.75^W/Hz), with the LLRGs displaying a flat spatial distribution in contrast to the centrally peaked HLRGs. A color-morphology classification shows that the HLRGs are composed primarily of galaxies with old stellar populations, whereas the LLRGs have a much more diverse composition. We do not see a correlation between the cluster radio fraction and cluster blue fraction. However, there is a moderate anticorrelation with richness, suggesting that a rich cluster is less likely to have radio-bright galaxies, whether the radio emission is due to active galactic nuclei or star formation.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/131/2426
- Title:
- Optical and radio study of Abell 2111
- Short Name:
- J/AJ/131/2426
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an in-depth analysis of the Butcher-Oemler cluster A2111, including new optical spectroscopy plus a deep Very Large Array (VLA) radio continuum observation. These are combined with optical imaging from the Sloan Digital Sky Survey (SDSS) to assess the activity and properties of member galaxies. Prior X-ray studies have suggested A2111 to be a head-on cluster merger, a dynamical state that might be connected to the high level of activity inferred from its blue fraction. We are able to directly assess this claim, using our spectroscopic data to identify 95 cluster members among 196 total galaxy spectra. We are able to detect 175 optical sources from the SDSS in our VLA radio data, of which 35 have redshift information.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/2982
- Title:
- Optical and UV colors of Coma galaxies
- Short Name:
- J/MNRAS/421/2982
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and analyse optical and ultraviolet (UV) colours for passive and optically-red Coma cluster galaxies for which we have spectroscopic age and element abundance estimates. Our sample of 150 objects covers a wide range in mass, from giant ellipticals down to the bright end of the dwarf-galaxy regime. Galaxies with ongoing star formation have been removed using strict H{alpha} emission-line criteria. We focus on the colours FUV-i, NUV-i, FUV-NUV, u*-g and g-i. We find that all of these colours are correlated with both luminosity and velocity dispersion at the >5{sigma} level, with FUV-i and FUV-NUV becoming bluer with increasing 'mass' while the other colours become redder. We perform a purely empirical analysis to assess what fraction of the variation in each colour can be accounted for by variations in the average stellar populations, as traced by the optical spectra.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/1758
- Title:
- Optical emission lines in galaxy cluster cores 1
- Short Name:
- J/MNRAS/460/1758
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an Integral Field Unit survey of 73 galaxy clusters and groups with the VIsible Multi Object Spectrograph on the Very Large Telescope. We exploit the data to determine the H{alpha} gas dynamics on kpc scales to study the feedback processes occurring within the dense cluster cores. We determine the kinematic state of the ionized gas and show that the majority of systems (~2/3) have relatively ordered velocity fields on kpc scales that are similar to the kinematics of rotating discs and are decoupled from the stellar kinematics of the brightest cluster galaxy. The majority of the H{alpha} flux (>50 per cent) is typically associated with these ordered kinematics and most systems show relatively simple morphologies suggesting they have not been disturbed by a recent merger or interaction. Approximately 20 per cent of the sample (13/73) have disturbed morphologies which can typically be attributed to active galactic nuclei activity disrupting the gas. Only one system shows any evidence of an interaction with another cluster member. A spectral analysis of the gas suggests that the ionization of the gas within cluster cores is dominated by non-stellar processes, possibly originating from the intracluster medium itself.
- ID:
- ivo://CDS.VizieR/VII/169
- Title:
- Optical Identifications of IRAS Point Sources
- Short Name:
- VII/169
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical identifications are given of IRAS point sources: 312 sources in a 304 square deg area centred on the South Galactic Pole, of which 148 are identified with stars, 154 with galaxies and 10 are unidentified down to 21st magnitude; 206 point sources in a 113 square deg area centred on the Virgo cluster, of which 54 are identified with stars, 113 with optically bright (B_J<16) galaxies, 32 with faint galaxies, and 7 are apparently empty fields; (66, 114, 61) sources in the regions of (Fornax, Hydra I, Coma) cluster of galaxies, of which (35, 48, 18) are identified with stars, (43, 58, 41) with galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/495/379
- Title:
- Optical radial velocities in A85
- Short Name:
- J/A+A/495/379
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this series of papers we explore the evolution of late-type galaxies in the rich cluster Abell 85. In this first paper we revisit the complex dynamical state of A 85 by using independent methods. First, we analyze the galaxy redshift distribution towards A 85 in the whole range 0-40000km/s, and determine the mean redshifts of the background clusters A 87 and A 89, very close in projection to A 85. Then we search for substructures in A 85 by considering the 2D galaxy distribution of its members (13000-20000km/s) and by applying the kinematical 3D {Delta}-test to both projected positions and radial velocities.
- ID:
- ivo://CDS.VizieR/J/AJ/109/14
- Title:
- Optical spectroscopy of Abell clusters. I.
- Short Name:
- J/AJ/109/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a program of optical spectroscopy of radio galaxies in rich clusters. Redshifts are reported for 268 radio galaxies or close companions in Abell clusters and 36 objects which turned out to be foreground or background objects. Absolute line strengths are also reported for the 3727{AA} [OII] line and the [NII]/H{alpha} complex. We find no evidence that the radio activity in our sample of mostly FR I radio galaxies is associated with emission-line luminosities above those found in "normal" galaxies of the same absolute magnitude and optical type. We also find that the radial velocity differences between radio galaxies and the cluster mean seem mainly to be a function of galaxy absolute magnitude rather than radio properties.
- ID:
- ivo://CDS.VizieR/J/A+A/489/11
- Title:
- Optical view of Abell 85 filament region
- Short Name:
- J/A+A/489/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an optical investigation of the Abell 85 cluster filament (z=0.055) previously interpreted in X-rays as groups falling on to the main cluster. We compare the distribution of galaxies with the X-ray filament, and investigate the galaxy luminosity functions in several bands and in several regions. We search for galaxies where star formation may have been triggered by interactions with intracluster gas or tidal pressure due to the cluster potential when entering the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/723/985
- Title:
- Orientation of galaxies in galaxy clusters
- Short Name:
- J/ApJ/723/985
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the spatial orientations of galaxies in 247 optically selected rich Abell clusters which have at least 100 members in the considered area. We investigated the relation between angles that give information about galaxy angular momenta and the number of members in each structure. The position angles of the galaxies' major axes, as well as two angles describing the spatial orientation of the galaxy plane, were tested for isotropy by applying three different statistical tests. It is found that the values of the statistics increase with the amount of the galaxies' members, which is equivalent to the existence of a relation between anisotropy and the number of galaxies in a cluster. The search for connection between the galaxies' alignments and Bautz-Morgan (BM) morphological types of examined clusters showed a weak dependence. A statistically marginal relation between velocity dispersion and cluster richness was observed. In addition, it was found that the velocity dispersion decreases with BM type at almost 3{sigma} level. These results show the dependence of alignments with respect to clusters' richness, which can be regarded as an environmental effect.
- ID:
- ivo://CDS.VizieR/J/AJ/155/188
- Title:
- Origin of nuclear activity in low-power radio galaxies
- Short Name:
- J/AJ/155/188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using large samples containing nearly 2300 active galaxies of low radio luminosity (1.4 GHz luminosity between 2x10^23^ and 3x10^25^ W/Hz, essentially low-excitation radio galaxies) at z~<0.3, we present a self-contained analysis of the dependence of the nuclear radio activity on both intrinsic and extrinsic properties of galaxies, with the goal of identifying the best predictors of the nuclear radio activity. While confirming the established result that stellar mass must play a key role on the triggering of radio activities, we point out that for the central, most massive galaxies, the radio activity also shows a strong dependence on halo mass, which is not likely due to enhanced interaction rates in denser regions in massive, cluster-scale halos. We thus further investigate the effects of various properties of the intracluster medium (ICM) in massive clusters on the radio activities, employing two standard statistical tools, principle component analysis and logistic regression. It is found that ICM entropy, local cooling time, and pressure are the most effective in predicting the radio activity, pointing to the accretion of gas cooling out of a hot atmosphere to be the likely origin in triggering such activities in galaxies residing in massive dark matter halos. Our analysis framework enables us to logically discern the mechanisms responsible for the radio activity separately for central and satellite galaxies.
