Оглавление
Изображения
Загрузить ваше изображение
DSS Images Other Images
Публикации по объекту
Brightest cluster galaxies as standard candles
We investigate the use of brightest cluster galaxies (BCGs) as standardcandles for measuring galaxy peculiar velocities on large scales. Wehave obtained precise large-format CCD surface photometry and redshiftsfor an all-sky, volume-limited (z less than or = 0.05) sample of 199BCG. We reinvestigate the Hoessel (1980) relationship between the metricluminosity, Lm, within the central 10 kpc/h of the BCGs andthe logarithmic slope of the surface brightness profile, alpha. TheLm-alpha relationship reduces the cosmic scatter inLm from 0.327 mag to 0.244 mag, yielding a typical distanceaccuracy of 17% per BCG. Residuals about the Lm-alpharelationship are independent of BCG luminosity, BCG B - Rccolor, BCG location within the host cluster, and richness of the hostcluster. The metric luminosity is independent of cluster richness evenbefore correcting for its dependence on alpha, which provides furtherevidence for the unique nature of the BCG luminosity function. Indeed,the BCG luminosity function, both before and after application of thealpha-correction, is consistent with a single Gaussian distribution.Half the BCGs in the sample show some evidence of small color gradientsas a function of radius within their central 50 kpc/h regions but withalmost equal numbers becoming redder as becoming bluer. However, withthe central 10 kpc/h the colors are remarkably constant -- the mean B -Rc color is 1.51 with a dispersion of only 0.06 mag. Thenarrow photometric and color distributions of the BCGs, the lack of'second-parameter' effects, as well as the unique rich clusterenvironment of BCGs, argue that BCGs are the most homogeneous distanceindicators presently available for large-scale structure research.
| The dynamics and structure of rich clusters of galaxies. I - Velocity data
An extensive spectroscopic study of 10 rich southern X-ray clusters ofgalaxies is presented. Between 40 and 200 redshifts have been obtainedin the field of each of the clusters, which cover a wide range ofmorphological types and richnesses. Applying rigorous statisticalanalyses to the total data base of 1000 precise radial velocitiesprovides the necessary information to undertake a thorough dynamicalinvestigation of these individual clusters and of cluster systems ingeneral.
| The HEAO A-1 all-sky survey of fast X-ray transients
Ten fast X-ray transient sources were discovered in the first completepass of the sky by the HEAO A-1 Sky Survey Experiment, including 7relatively faint sources and 3 bright ones. The survey technique andeach of the transients are described. Four of the transients areidentified with active coronal sources; the remaining ones areunidentified. The statistical properties of the total sample of 10sources are discussed, including event rates, distribution on the sky,and the number-flux distribution.
| Southern Galaxy Catalogue.
Not Available
| A catalog of morphological types in 55 rich clusters of galaxies
Data are presented from a study of 55 rich clusters of galaxies. Thedata include positions, morphological types, estimated total magnitudes,bulge sizes, and ellipticities for about 6000 galaxies, as determinedfrom high scale photographic plates. Data reduction procedures aredescribed, and a brief analysis of cluster richness, which indicatesthat Abell richness classes are only rough indicators of total clustermembership, is included.
|
Добавить новую статью
Внешние ссылки
- - Внешних ссылок не найдено -
Добавить внешнюю ссылку
Группы:
|
Наблюдательные данные и астрометрия
Каталоги и обозначения:
|
