Environmental Dependence of Different Colors for the Apparent Magnitude-Limited Main Galaxy Sample of the SDSS DR7

Abstract

The apparent magnitude-limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 7 is used to investigate the environmental dependence of

Luminosity-Environment Relation in the Lowz Sample of the SDSS-III

“…Overall, the result of Deng (2012) showed that the environmental dependence of galaxy luminosities is very strong in the redshift region 0.02 ≤ z ≤ 0.10. Combining with the results from Deng et al (2012cDeng et al ( , 2013, one can also observe that in the apparent-magnitude limited Main galaxy sample the environmental dependence of galaxy properties becomes weak with increasing redshift. Table 1 also shows that in the high redshift region, the KS probability of all five band luminosities rises considerably with increasing redshift.…”

“…Following our previous works (e.g., Deng 2012; Deng et al 2012cDeng et al , 2013Deng & Zou 2014a), we measure the projected local density Σ 5 , which is computed from the distance to the 5th nearest neighbor within a redshift slice of ± 1000 km s −1 of each galaxy (e.g., Goto et al 2003;Balogh et al 2004a,b), and divide the LOWZ sample into subsamples with a redshift bin size of ∆z = 0.01. In each subsample, we arrange galaxies in density order from the smallest to the largest, select approximately 5% of the galaxies, construct two samples at both density extremes according to the density, and compare the distributions of all five band luminosities in the lowest density regime with those in the densest regime.…”

“…In the previous works (e.g., Deng 2012; Deng et al 2012cDeng et al , 2013Deng & Zou 2014a), the histogram distributions and the Kolmogorov-Smirnov (KS) test were used to examine the environmental dependence of galaxy properties. The histograms can directly show the difference in the distribution of galaxy properties at both extremes of density, while the KS test can serve as a quantitative comparison which demonstrates the degree of similarity or difference between two independent distributions in a figure, by calculating a probability value.…”

“…To decrease the influence of the radial selection effect on statistical results, Deng (2012) divided the entire apparent-magnitude limited galaxy sample into many subsamples with a redshift bin size of ∆z = 0.01, examined the environmental dependence of all the five band luminosities of the subsamples in each redshift bin, and found that all the five band luminosities apparently correlate with the local environment, especially in the redshift range 0.05 ≤ z ≤ 0.10. Some works demonstrated that, although the environmental dependence of galaxy properties in each subsample is likely to be greatly decreased, this dependence can still be observed if it exists (e.g., Deng 2012; Deng et al 2012cDeng et al , 2013. Statistical results of these works also implied that environmental dependence of galaxy properties becomes weak with increasing redshift in the apparent-magnitude limited Main galaxy sample.…”

“…Second, some studies demonstrated that the influence of environment on galaxy properties is likely to be fairly different in different redshift regions. For example, in the local Universe, galaxy colors and stellar mass strongly depend on the local environment (e.g., Brown et al 2000;Zehavi et al 2002;Kauffmann et al 2004;Blanton et al 2005;Li et al 2006;Deng et al 2008aDeng et al ,b, 2009aDeng et al , 2012cDeng et al , 2013, while in the intermediate and high redshift regions, these dependences are very weak (e.g., Cucciati et al 2006;Grützbauch et al 2011a,b;Deng 2014;Deng & Zou 2014b). Thus, when exploring the environmental dependence of galaxy properties, the use of galaxy samples with different redshift regions is necessary.…”