Isolated Main Galaxy Pairs from the SDSS Data Release 4

• Published in: Chinese journal of astronomy and astrophysics Vol. 6; no. 4; pp. 411 - 420
• Main Authors: Deng, Xin-Fa, Chen, Yi-Qing, Wu, Ping, Luo, Cheng-Hong, He, Ji-Zhou
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.08.2006; Mathematics and Physics College,Nanchang University,Nanchang 330047%Management College, Nanchang University, Nanchang 330047
• Subjects: 交互作用; 数据离散; 空间物质; galaxy: fundamental parameters-galaxies: interactions
• ISSN: 1009-9271
• DOI: 10.1088/1009-9271/6/4/03

From the Main galaxy data of the SDSS Data Release 4 （SDSS4）, we have identiffed close galaxy pairs at neighbourhood radius R = 100 kpc by three-dimensional cluster analysis. Using the criterion that an ＂isolated galaxy pair＂ must be separated from its ＂nearest neighbor＂ by more than 500 kpc, we constructed an isolated galaxy pair sample of 1158 pairs. We also constructed a random pair sample by randomly selecting 1158 galaxy pairs from the Main galaxy sample, which has the same redshift distribution as the isolated galaxy pair sample, and in which the two components of any pair have the same redshifts. Comparative studies of luminosity and size between the members of the galaxy pairs are performed. We find and further confirm there is no tendency for paired galaxies to have similar luminosities or sizes. From the isolated pair sample we also selected a subsample with the magnitude limit of the primary raised by 2 magnitudes, so as to include pairs in which the secondary is 2 magnitudes fainter than the primary. This subsample contains 82 pairs. A random pair sample is similarly constructed.