Showing papers on "Brightest cluster galaxy published in 1980"
TL;DR: In this paper, a study of the galaxy populations in 55 rich clusters is presented together with a discussion of the implications for the formation and/or evolution of different morphological types.
Abstract: A study of the galaxy populations in 55 rich clusters is presented together with a discussion of the implications for the formation and/or evolution of different morphological types. A well-defined relationship is found between local galaxy density and galaxy type, which, in agreement with previous studies, indicates an increasing elliptical and SO population and a corresponding decrease in spirals with increasing density.
3,368 citations
267 citations
221 citations
TL;DR: In this paper, it was shown that the double quasar is almost certainly the multiple image of a single object produced by a gravitational lens, which can easily reproduce all of the present observations.
Abstract: Deep CCD pictures show a rich cluster of galaxies around the double quasar Q0957 + 561 as well as faint extended wings on the image of the southern quasar. Calculations of gravitational imaging by King model mass distributions show that the cluster and the brightest galaxy together, acting as a gravitational lens on the light from a single, more distant QSO, can easily reproduce all of the present observations. It is concluded that the double quasar is almost certainly the multiple image of a single object produced by a gravitational lens.
124 citations
TL;DR: In this article, two-color aperture photometry of the brightest galaxies in a complete sample of nearby Abell clusters is presented; the results are used to anchor the bright end of the Hubble diagram; essentially the entire formal error for this method is then due to the sample of distant clusters used.
Abstract: Two-color aperture photometry of the brightest galaxies in a complete sample of nearby Abell clusters is presented. The results are used to anchor the bright end of the Hubble diagram; essentially the entire formal error for this method is then due to the sample of distant clusters used. New determinations of the systematic trend of galaxy absolute magnitude with the cluster properties of richness and Bautz-Morgan type are derived. When these new results are combined with the Gunn and Oke (1975) data on high-redshift clusters, a formal value (without accounting for any evolution) of q sub 0 = -0.55 + or - 0.45 (1 standard deviations) is found.
103 citations
TL;DR: In this article, the first-ranked galaxy in 108 Abell clusters is presented and the structure data support the dynamical friction evolution model and the short lifetimes of such systems provide the best available evidence that ongoing evolution actually occurs.
Abstract: Surface photometry of the first-ranked galaxy in 108 Abell clusters is presented. Galaxy structure, as parameterized by simple Hubble law models, is found to correlate with galaxy absolute magnitude and cluster structure. All the structure data support the dynamical friction evolution model. Twenty-eight percent of the galaxies have multiple component nuclei; the short lifetimes of such systems provide the best available evidence that ongoing evolution actually occurs. Average magnitude and structure evolution rates are derived from the data.
61 citations
35 citations
31 citations
TL;DR: In this article, radio maps and optical identifications of a sample of sources in the directions of 21 Yerkes poor cluster fields are presented. The majority of the cluster radio sources are associated with the dominant D or cD galaxies (approximately 70 percent).
Abstract: VLA radio maps and optical identifications of a sample of sources in the directions of 21 Yerkes poor cluster fields are presented. The majority of the cluster radio sources are associated with the dominant D or cD galaxies (approximately 70 percent). Our analysis of dominant galaxies in rich and poor clusters indicates that these giant galaxies are much more often radio emitters (approximately 25 percent of cD's are radio active in the poor clusters), have steeper radio spectra, and have simpler radio morphologies (i.e., double or other linear structure) than other less bright ellipticals. A strong continuum of radio properties in cD galaxies is seen from rich to poor clusters. It is speculated that the location of these dominant galaxies at the cluster centers (i.e., at the bottom of a deep, isolated gravitational potential well) is the crucial factor in explaining their multifrequency activity. Galaxy cannibalism and gas infall models as fueling mechanisms for the observed radio and X-ray emission are discussed
27 citations
01 Jan 1980
TL;DR: The dominant X-ray emission from galaxy clusters is very likely to be thermal Bremsstrahlung from a diffuse, hot intracluster medium (ICM) with maximum density n ≃ 10−3 cm−3, temperature T ≃ 108 °K and near-solar composition as discussed by the authors.
Abstract: The dominant X-ray emission from galaxy clusters is very likely to be thermal Bremsstrahlung from a diffuse, hot intracluster medium (ICM) with maximum density n ≃ 10−3 cm−3, temperature T ≃ 108 °K and near-solar composition The main evidence is based on integrated spectra: shape and intensity of the continuum, and strength of very high excitation lines up to Fe XXV and XXVI in several clusters (Mushotzky et al 1978 and references therein)In dependent evidence of a dense hot ICM extending out to several core radii rc has been provided by the discovery and the interpretation of “head-tail” radio galaxies (TRG, reviewed by Harris 1977) Direct evidence of extended X-ray emission had been obtained from coarse scannings by the UHURU satellite (cf Gursky and Schwartz 1977) and from imaging observations of Perseus and Coma Clusters (Gorenstein et al 1978, 1979)
TL;DR: In this article, X-ray observations of the galaxy clusters Abell 2319 and 576 show a reduced temperature of the microwave background due to the Suniaev-Zeldovich effect.
Abstract: The X-ray observations of the galaxy clusters Abell 2319 and 576 show a reduced temperature of the microwave background due to the Suniaev-Zeldovich effect. The X-ray maps indicate smooth emission in these clusters concentrated toward the optical center; the surface brightness in the 1-3 keV band falls with the inverse square of radius outside a small core, and fits the Hubble's law of optical surface brightness of elliptical galaxies. The low temperature indicates that in A576 (1) the core radius of the gravitational potential is two to three times larger than inferred from galaxy counts, (2) the temperature rises with radius over most of the cluster and falls to zero at large radii, and (3) the gas does not obey the equation of state.
TL;DR: In this paper, the authors examined the motion of galaxies through the hot intracluster gas and found that a Kelvin-Helmholtz instability develops at the interface between the moving galaxy and the gas.
Abstract: The motion of galaxies through the hot intracluster gas is examined. It is found that a Kelvin-Helmholtz instability develops at the interface between the moving galaxy and the gas. Its effect is gas stripping from the moving galaxy: the rate of stripping is estimated. The role of viscosity in this process is discussed.
TL;DR: In this paper, the nearby X-ray QSO MR 2251: 178 is associated with a cluster of approximately 50 galaxies and a faint nebulosity is detected around the QSO.
Abstract: The nearby (z=0.0653) X-ray QSO MR 2251: 178 is shown to be associated with a cluster of approximately 50 galaxies. A faint nebulosity is detected around the QSO. If this implies that the QSO lies in a galaxy, then the galaxy is a magnitude or more fainter than the central D galaxy of the cluster. A compact radio galaxy 39'' north of the QSO which displays moderately strong (O II) and H..beta.. emission and a blue stellar continuum is also shown to be a cluster member.
TL;DR: In this article, the luminosity of supergiant cD galaxies in particular, and the Bautz-Morgan sequence of galaxy types in general, is produced by dynamical evolutionary processes, and one expects to find a correlation between dynamical times and the magnitude difference between first and second brightest cluster members.
Abstract: If the luminosity of supergiant cD galaxies in particular, and the Bautz-Morgan sequence of galaxy types in general, is produced by dynamical evolutionary processes, then one expects to find a correlation between dynamical times and ..delta..M/sub 12/, the magnitude difference between first and second brightest cluster members.
TL;DR: In this article, the expected (V - R) color distribution for a centrally condensed, relaxed cluster of E and S0 galaxies has been calculated as a function of redshift.
Abstract: The expected (V - R) color distribution for a centrally condensed, relaxed cluster of E and S0 galaxies has been calculated as a function of redshift. Because of the differences in the ultraviolet spectra of E and S0 galaxies, which are correlated with absolute magnitude, the spread in (V - R) colors for such a cluster becomes increasingly wide for increasing redshift. This effect becomes pronounced for redshifts of 0.4 and beyond. Thus evidence for the color evolution of cluster galaxies will be seen as an additional broadening of the color distribution.
Journal Article•
Journal Article•
TL;DR: B-V color profiles to low surface brightness are presented for the normal giant elliptical galaxies NGC 4472 and NGC 5846 and the cD galaxy NGC 6166.
Abstract: B-V color profiles to low surface brightness are presented for the normal giant elliptical galaxies NGC 4472 and NGC 5846 and the cD galaxy NGC 6166. Compared to the ellipticals, the cD shows a larger gradient and a somewhat bluer outermost envelope. This behavior would seem most consistent with models for cD formation in which the extended halo is either capture tidal debris torn from the outer regions of cluster members during high-velocity encounters or the remains of lower-luminosity galaxies. Although the present small sample and the limited accuracy of measurement do not warrant firm conclusions, color profiles of cD galaxies seem a promising attack on the problem of cD origin.
TL;DR: In this article, the authors reviewed and compared recent counts of faint galaxies and intercompared them with applications to cosmology, the evolution of galaxies, and the distribution of luminous matter.
Abstract: Recent counts of faint galaxies are reviewed and intercompared. Applications to cosmology, the evolution of galaxies, and the distribution of luminous matter are discussed. The interpretation of the data requires a detailed understanding of the properties of faint galaxy images and the methods used to measure these images.