Some Properties of Active Galactic Nuclei in the Volume-Limited Main Galaxy Samples of SDSS Dr8

Comparison of some properties of star forming galaxies and active galactic nuclei between two BOSS galaxy samples from SDSS DR9

“…BPT classification in this Web is based on the methodology of Brinchmann et al (2004), which is completely the same as the methodology of Thomas et al (2013) adopted in this work. But the AGN fraction in two BOSS galaxy samples is much larger than that found in two volume-limited Main galaxy samples by Deng et al (2012a). This further shows that the AGN fraction indeed is correlated with some properties of galaxy samples.…”

“…In two volume-limited Main galaxy samples of the SDSS DR6 (Adelman-McCarthy et al 2008) above and below the value of * r M , Deng et al (2012c) demonstrated that the AGN fraction in the luminous volume-limited sample is ≈ 9.8% and the AGN fraction in the faint volume-limited sample is ≈ 4.3%. Deng et al (2012a) argued the difference of the AGN fraction obtained by different authors likely is due to these authors using different AGN classification techniques. However, in works of Deng et al (2012a) and Deng et al (2012c), two volume-limited Main galaxy samples above and below the value of * r M contain fairly different AGN fraction, even if the same AGN classification techniques were used in two samples.…”

“…Deng et al (2012a) argued the difference of the AGN fraction obtained by different authors likely is due to these authors using different AGN classification techniques. However, in works of Deng et al (2012a) and Deng et al (2012c), two volume-limited Main galaxy samples above and below the value of * r M contain fairly different AGN fraction, even if the same AGN classification techniques were used in two samples. Deng et al (2012a) and Deng et al (2012c) argued that the AGN fraction also is seriously influenced by properties of galaxy samples.…”

“…However, in works of Deng et al (2012a) and Deng et al (2012c), two volume-limited Main galaxy samples above and below the value of * r M contain fairly different AGN fraction, even if the same AGN classification techniques were used in two samples. Deng et al (2012a) and Deng et al (2012c) argued that the AGN fraction also is seriously influenced by properties of galaxy samples. Deng et al (2012a) used galaxy physical parameters derived by the MPA-JHU group (http://www.mpa-garching.mpg.de/SDSS/DR7/), such as BPT classification, stellar mass, nebular oxygen abundance, star formation rates (SFRs) and the specific SFR (SSFR).…”

“…For example, the AGN fraction obtained in some works was fairly different, from a few percent to ≈ 40% (Dressler et al 1985;Huchra & Burg 1992;Ho et al 1997;Carter et al 2001;Ivezic′ et al 2002;Miller et al 2003;Deng et al 2012aDeng et al , 2012c. This can be traced to two facts.…”