Structures and number-density distributions in clusters of galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900144547 ◽

1978 ◽

Vol 79 ◽

pp. 198-199

Author(s):

F. W. Baier

Keyword(s):

Clusters Of Galaxies ◽

Number Density ◽

Multiple Systems ◽

Preliminary Results ◽

Density Distributions ◽

Sky Survey

I would like to present some preliminary results of an investigation of 50 clusters of galaxies. For studying the clusters, Schmidt plates taken with the 2-metre universal telescope at Tautenburg and the prints of the Palomar Sky Survey were used. For all the clusters we determined isopleths to obtain detailed information about the distribution of galaxies. We have found well isolated clusters, double clusters, multiple systems and rather complicated structures.

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On structures and number-density distributions in clusters of galaxies

Astronomische Nachrichten ◽

10.1002/asna.19762970610 ◽

1976 ◽

Vol 297 (6) ◽

pp. 295-300 ◽

Cited By ~ 17

Author(s):

F. W. Baier

Keyword(s):

Clusters Of Galaxies ◽

Number Density ◽

Density Distributions

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Searching for Mg ii absorbers in and around galaxy clusters

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab637 ◽

2021 ◽

Vol 503 (3) ◽

pp. 4309-4319

Author(s):

Jong Chul Lee ◽

Ho Seong Hwang ◽

Hyunmi Song

Keyword(s):

Galaxy Clusters ◽

Detection Rate ◽

Massive Star ◽

Sloan Digital Sky Survey ◽

Number Density ◽

Cluster Galaxies ◽

Star Forming ◽

Quasar Spectra ◽

Sky Survey ◽

The Galaxy

ABSTRACT To study environmental effects on the circumgalactic medium (CGM), we use the samples of redMaPPer galaxy clusters, background quasars, and cluster galaxies from the Sloan Digital Sky Survey (SDSS). With ∼82 000 quasar spectra, we detect 197 Mg ii absorbers in and around the clusters. The detection rate per quasar is 2.7 ± 0.7 times higher inside the clusters than outside the clusters, indicating that Mg ii absorbers are relatively abundant in clusters. However, when considering the galaxy number density, the absorber-to-galaxy ratio is rather low inside the clusters. If we assume that Mg ii absorbers are mainly contributed by the CGM of massive star-forming galaxies, a typical halo size of cluster galaxies is smaller than that of field galaxies by 30 ± 10 per cent. This finding supports that galaxy haloes can be truncated by interaction with the host cluster.

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A new Description of Probability Density Distributions of Polar Mesospheric Clouds (PMC)

10.5194/acp-2018-642 ◽

2018 ◽

Author(s):

Uwe Berger ◽

Gerd Baumgarten ◽

Jens Fiedler ◽

Franz-Josef Lübken

Keyword(s):

Probability Density ◽

Mass Density ◽

Particle Radius ◽

Number Density ◽

Data Set ◽

Statistical Probability ◽

Polar Mesospheric Clouds ◽

Density Distributions ◽

Mesospheric Clouds ◽

Probability Density Distributions

Abstract. In this paper we present a new description about statistical probability density distributions (pdfs) of Polar Mesospheric Clouds (PMC) and noctilucent clouds (NLC). The analysis is based on observations of maximum backscatter, ice mass density, ice particle radius, and number density of ice particles measured by the ALOMAR RMR-lidar for all NLC seasons from 2002 to 2016. From this data set we derive a new class of pdfs that describe the statistics of PMC/NLC events which is different from previously statistical methods using the approach of an exponential distribution commonly named g-distribution. The new analysis describes successfully the probability statistic of ALOMAR lidar data. It turns out that the former g-function description is a special case of our new approach. In general the new statistical function can be applied to many kinds of different PMC parameters, e.g. maximum backscatter, integrated backscatter, ice mass density, ice water content, ice particle radius, ice particle number density or albedo measured by satellites. As a main advantage the new method allows to connect different observational PMC distributions of lidar, and satellite data, and also to compare with distributions from ice model studies. In particular, the statistical distributions of different ice parameters can be compared with each other on the basis of a common assessment that facilitate, for example, trend analysis of PMC/NLC.

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White Dwarf Stars

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194517600230 ◽

2017 ◽

Vol 45 ◽

pp. 1760023

Author(s):

S. O. Kepler ◽

Alejandra Daniela Romero ◽

Ingrid Pelisoli ◽

Gustavo Ourique

Keyword(s):

White Dwarf ◽

Final Stage ◽

White Dwarfs ◽

Sloan Digital Sky Survey ◽

Dwarf Stars ◽

Multiple Systems ◽

White Dwarf Stars ◽

Sky Survey ◽

Data Release ◽

Low Mass

White dwarf stars are the final stage of most stars, born single or in multiple systems. We discuss the identification, magnetic fields, and mass distribution for white dwarfs detected from spectra obtained by the Sloan Digital Sky Survey up to Data Release 13 in 2016, which lead to the increase in the number of spectroscopically identified white dwarf stars from 5[Formula: see text]000 to 39[Formula: see text]000. This number includes only white dwarf stars with [Formula: see text], i.e., excluding the Extremely Low Mass white dwarfs, which are necessarily the byproduct of stellar interaction.

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Extragalactic X-ray sources and the diffuse X-ray background

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1979.0060 ◽

1979 ◽

Vol 366 (1726) ◽

pp. 391-402 ◽

Cited By ~ 3

Keyword(s):

Spatial Distribution ◽

Euclidean Space ◽

Active Galaxies ◽

Clusters Of Galaxies ◽

Optical Identification ◽

X Ray ◽

Luminosity Functions ◽

Sky Survey ◽

Order Of Magnitude ◽

X Ray Background

Results from the Ariel 5 sky survey instrument relating to the properties and the spatial distribution of extragalactic X-ray sources are discussed. The lg N -lg S relation for sources in the 2A catalogue is consistent with a uniform distribution of sources in Euclidean space. In addition, measurements of fluctuations in the X-ray background suggest that the Euclidean form of the source counts can be extrapolated to flux levels at least an order of magnitude fainter than the 2A catalogue limit. Information is also available from the optical identification of 2A sources which, through redshift measurements, enables the X-ray luminosity functions of the two main classes of source, namely clusters of galaxies and active galaxies, to be determined. The luminosity functions can be used to calculate the contribution of clusters of galaxies and active galaxies to the diffuse X-ray background in the 2-10 keV range. It is found that cosmological evolution of one or both populations is required to account for the diffuse X-ray background entirely in terms of the integrated emission from these sources.

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9.5 Multiple systems and clusters of galaxies

Astronomy and Astrophysics - Landolt-Börnstein - Group VI Astronomy and Astrophysics ◽

10.1007/10201941_148 ◽

2005 ◽

pp. 674-675

Author(s):

S. van den Bergh

Keyword(s):

Clusters Of Galaxies ◽

Multiple Systems

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Optical Identification of the ROSAT All-Sky Survey Sources in Two 2° × 2° Fields

International Astronomical Union Colloquium ◽

10.1017/s0252921100040653 ◽

1997 ◽

Vol 159 ◽

pp. 427-428

Author(s):

Y. Zhao ◽

J. Zhong ◽

J. Wei ◽

J. Hu ◽

Q. Li

Keyword(s):

Ccd Camera ◽

Seyfert Galaxies ◽

Astronomical Observatory ◽

Active Galaxies ◽

Clusters Of Galaxies ◽

Late Type ◽

Optical Identification ◽

X Ray ◽

Sky Survey

AbstractWe used the CCD camera and spectrograph of the 2.16-m telescope of Beijing Astronomical Observatory to identify the ROSAT All-Sky survey sources in two 2° Ü 2° fields. Of a total of 16 X-ray sources, we identified 13 of them as follows: two QSOs, two Seyfert galaxies, two active galaxies, two clusters of galaxies, and five late-type stars. Three X-ray sources remained unidentified.

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Formation Times for Rich Clusters of Galaxies

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000015113 ◽

1977 ◽

Vol 3 (2) ◽

pp. 140-142 ◽

Cited By ~ 1

Author(s):

B. M. Lewis

Keyword(s):

Gaussian Distribution ◽

Large Scale ◽

Velocity Dispersion ◽

Large Scale Structure ◽

Elliptical Galaxies ◽

Scale Structure ◽

Clusters Of Galaxies ◽

Number Density ◽

Radial Gradient ◽

The Universe

Rich clusters of galaxies are a common feature of the large-scale structure of the Universe. Those studied so far, show striking regularities with (a)a smooth radial gradient of number density.(b)’isothermal’ distributions, which according to Bahcall (1975) have a scatter of only ±15% in the size of their characteristic core radii.(c)their limiting structural diameters are ~50 Mpc (cf. Abell, 1975), if they are identified with superclusters.(d)the magnitude of the velocity dispersion about their centres is generally 600-1000 km s-1, and the velocities are cpnsistent with a gaussian distribution (Yahil and Vidal, 1976; also Faber and Dressier, 1976).(e)The extreme velocities are generally within ±3000 km s-1, and for Coma are ∼2400 km s-1 (Tifft and Gregory, 1976).(f)elliptical galaxies tend to predominate near the centre, spirals in the surrounding loose groups.

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Optical Identifications of Radio Sources with Accurate Positions Using the UKST IIIa-J Plates

International Astronomical Union Colloquium ◽

10.1017/s0252921100107109 ◽

1984 ◽

Vol 78 ◽

pp. 481-487

Author(s):

Ann Savage ◽

David L. Jauncey ◽

Michael J. Batty ◽

S. Gulkis ◽

D.D. Morabito ◽

...

Keyword(s):

Radio Sources ◽

Preliminary Results ◽

Sky Survey ◽

Optical Identifications

SummaryThree radio identification programmes are described which are drawn from radio samples with accurate radio positions (< 2" arc rms). Optical identifications are being made on the basis of radio-optical positional coincidence alone, without regard to colour or morphology, using the UKST IIIa-J sky survey to a limiting magnitude of 22.5. Some preliminary results are presented.

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