The Nuclear Activities of Nearby S0 Galaxies

Abstract

We present a study of nuclear activities in nearby S0 galaxies. After crossmatching the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) with the Third Reference Catalog of Bright Galaxies (RC3) and visually checking the SDSS images, we derive a sample of 583 S0 galaxies with the central spectrophotometric information. In order to separate nebular emission lines from the underlying stellar contribution, we fit the stellar population model to the SDSS spectra of these S0 galaxies. According to the BPT diagram, we find that 8% of S0 galaxies show central star-forming activity, while the fractions of Seyfert, Composite and LINERs are 2%, 8%, and 21.4%, respectively. We also find that star-forming S0s have the lowest stellar masses, over one magnitude lower than the others, and that the active S0s locate mainly in the sparse environment, while the normal S0s in the dense environment, which might suggest that the environment plays an important role in quenching star formation and/or AGN activity in S0 galaxies. By performing bulge-disk decomposition of 45 star-forming S0s in g-and r-bands with the 2D fitting software Galfit, as well as exploiting the catalog of 2D photometric decompositions of Meert et al. (2015), we find that the bulges of ∼ 1/3 star-forming S0 galaxies (16/45) are bluer than their disks, while for other types of S0s, the bulge and disk components show similar color distributions. Besides, the Sérsic index of most star-forming S0s bulges is less than 2, while for normal S0s, it is between 2 and 6.

Double-peak emission line galaxies in the SDSS catalogue

“…Kannappan 2004;Kewley et al 2006a). Xiao et al (2016) find about 8% of an S0 sample exhibits central star formation. They also found that the majority of these SF S0 galaxies have a stellar mass below 10 10.6 M .…”

The Stellar Contents of Intermediate-mass Disk Galaxies in the Virgo Cluster. I. GMOS Spectra* † ‡

“…The bulge radius coincides with features in the J − K color profiles of NGC 4305,NGC 4497,and NGC 4584. Bulges that are redder than the surrounding disk are a common feature in larger S0s (e.g. Xiao et al 2016). Neglecting the color measurements in the outermost bins, which are susceptible to errors in sky subtraction and noise, then there are systematic J −K gradients in NGC 4305, NGC 4491, and NGC 4584, in the sense that J − K becomes smaller towards larger radii.…”

The Physical Characteristics of Interstellar Medium in NGC 3665 with Herschel Observations*

“…we derive logΣ SFR ∼ −0.78 M yr −1 kpc −2 , which is lower than the mean value, −0.48 M yr −1 kpc −2 , of 45 star-forming S0 galaxies with the same method (Xiao et al 2016).…”

“…We obtained that the nebular extinction, A V,nebular , for NGC 3665 is ∼ 1.3, which is larger than the mean value, 1.06 ± 0.66, of 45 star-forming S0 galaxies (Xiao et al 2016) from the Sloan Digital Sky Survey (SDSS; Abazajian et al 2009).…”