scholarly journals Morphological Distribution of Galaxies in Some Nearby Clusters

2019 ◽  
Vol 28 (1) ◽  
pp. 98-109
Author(s):  
Mariwan A. Rasheed ◽  
Khalid K. Mohammad
Keyword(s):  
Survey Data ◽  
Concentration Index ◽  
Color Space ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Late Type ◽  
Sky Survey ◽  
Data Release ◽  
The Galaxy ◽  
Morphological Distribution

Abstract We study the morphological distribution of galaxies in some nearby clusters, using the Sloan Digital Sky Survey – Data Release 9 (SDSS-DR9). The segregation between early-type galaxies and late-type ones is investigated in g – r / u – g color space, using the color cut u – r = 2.22. The results are compared with those obtained using a color cut that changes with magnitude. They are found to be consistent, particularly for late-type galaxies. The results obtained by the fixed color-cut criterion are also found to be consistent with those obtained by the inverse concentration index parameter, especially for early-type galaxies. Comparable results are obtained for the stacked sample, whose morphologies, given by the fixed color-cut criterion are compared with the visual morphologies provided by the Galaxy Zoo project. A good degree of consistency is seen, which becomes more evident for late-type galaxies.

scholarly journals The Properties of Isolated Main Galaxies in Sloan Digital Sky Survey Data Release 3 (SDSS DR3)

2006 ◽  
Vol 23 (2) ◽  
pp. 76-81 ◽  
Author(s):  
Xinfa Deng ◽  
Xinsheng Ma ◽  
Chenghong Luo ◽  
Qun Zhang ◽  
Qing-Hua Liao ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Survey Data ◽  
Sloan Digital Sky Survey ◽  
Early Type ◽  
Double Galaxy ◽  
Main Galaxy ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Sample

AbstractWe have constructed a Main galaxy subsample of 67777 galaxies with redshifts in the range 0.08 ≤ z ≤ 0.12 from the Sloan Digital Sky Survey Data Release 3. Using cluster analysis, two isolated Main galaxy samples were extracted from this subsample. The two isolated Main galaxy samples identified at different radii have the same properties. Additionally, we find fewer early-type galaxies in isolated Main galaxy samples than in a close double galaxy sample.

scholarly journals Influences of Galaxy Interactions on AGN Activity

2013 ◽  
Vol 30 ◽  
Author(s):  
Xin-Fa Deng ◽  
Guisheng Yu ◽  
Peng Jiang
Keyword(s):  
Survey Data ◽  
Strong Evidence ◽  
Sloan Digital Sky Survey ◽  
Limited Sample ◽  
Galaxy Interactions ◽  
Opposite Trend ◽  
Main Galaxy ◽  
Isolated Galaxies ◽  
Sky Survey ◽  
Data Release

AbstractUsing two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 7 , we explore influences of galaxy interactions on AGN activity. It is found that in the faint volume-limited sample, paired galaxies have a slightly higher AGN fraction than isolated galaxies, whereas in the luminous volume-limited sample, an opposite trend can be observed. The significance is <1σ. Thus, we do not observe strong evidence that interactions or mergers likely trigger the AGN activity.

The Mass Function of Void Galaxies in the Sloan Digital Sky Survey Data Release 2

2005 ◽  
Vol 621 (2) ◽  
pp. 643-650 ◽  
Author(s):  
David M. Goldberg ◽  
Timothy D. Jones ◽  
Fiona Hoyle ◽  
Randall R. Rojas ◽  
Michael S. Vogeley ◽  
...  
Keyword(s):  
Survey Data ◽  
Mass Function ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Void Galaxies ◽  
Data Release

scholarly journals The Sub-Eddington Boundary for the Quasar Mass–Luminosity Plane: A Theoretical Perspective

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 145 ◽  
Author(s):  
David Garofalo ◽  
Damian J. Christian ◽  
Andrew M. Jones
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Survey Data ◽  
Theoretical Perspective ◽  
Sloan Digital Sky Survey ◽  
Black Hole Mass ◽  
Massive Black Holes ◽  
Sky Survey ◽  
Data Release ◽  
Gap Paradigm

By exploring more than sixty thousand quasars from the Sloan Digital Sky Survey Data Release 5, Steinhardt & Elvis discovered a sub-Eddington boundary and a redshift-dependent drop-off at higher black hole mass, possible clues to the growth history of massive black holes. Our contribution to this special issue of Universe amounts to an application of a model for black hole accretion and jet formation to these observations. For illustrative purposes, we include ~100,000 data points from the Sloan Digital Sky Survey Data Release 7 where the sub-Eddington boundary is also visible and propose a theoretical picture that explains these features. By appealing to thin disk theory and both the lower accretion efficiency and the time evolution of jetted quasars compared to non-jetted quasars in our “gap paradigm”, we explain two features of the sub-Eddington boundary. First, we show that a drop-off on the quasar mass-luminosity plane for larger black hole mass occurs at all redshifts. But the fraction of jetted quasars is directly related to the merger function in this paradigm, which means the jetted quasar fraction drops with decrease in redshift, which allows us to explain a second feature of the sub-Eddington boundary, namely a redshift dependence of the slope of the quasar mass–luminosity boundary at high black hole mass stemming from a change in radiative efficiency with time. We are able to reproduce the mass dependence of, as well as the oscillating behavior in, the slope of the sub-Eddington boundary as a function of time. The basic physical idea involves retrograde accretion occurring only for a subset of the more massive black holes, which implies that most spinning black holes in our model are prograde accretors. In short, this paper amounts to a qualitative overview of how a sub-Eddington boundary naturally emerges in the gap paradigm.

Further Investigation of the Effect of Galaxy Interactions on Star Formation

2013 ◽  
Vol 22 (2) ◽  
Author(s):  
Xin-Fa Deng ◽  
Fuyang Zhang
Keyword(s):  
Star Formation ◽  
Survey Data ◽  
Control Sample ◽  
Sloan Digital Sky Survey ◽  
Apparent Magnitude ◽  
Galaxy Interactions ◽  
Main Galaxy ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Sample

AbstractFrom the apparent magnitude-limited the Main galaxy sample of the Sloan Digital Sky Survey Data Release 7, we construct a paired galaxy sample and a control sample without close companions with the projected separations

scholarly journals A VO study of SDSS AGNs with X-ray emission from ROSAT-PSPC pointed observations

2006 ◽  
Vol 2 (14) ◽  
pp. 581-581
Author(s):  
Robert J. Hanisch ◽  
Anatoly A. Suchkov ◽  
Timothy M. Heckman ◽  
Wolfgang H. Voges
Keyword(s):  
Survey Data ◽  
Sloan Digital Sky Survey ◽  
Radio Sources ◽  
X Ray ◽  
Sky Survey ◽  
Data Release

We use VO facilities to study AGNs with X-ray emission. We present a sample of 1744 of Type 1 AGNs from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) spectroscopic catalog with X-ray counterparts in the White-Giommi-Angelini catalogue (WGACAT) of ROSAT-pspc pointed observations. Of 1744 X-ray sources, 1410 (80.9%) are new AGN identifications. Of 4,574 SDSS DR4 AGNs for which we found radio matches in the catalogue of radio sources from the Faint Images of the Radio Sky at Twenty (FIRST) cm survey, 224 turned up in our sample of SDSS X-ray AGN.

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