AGN spiral galaxies in groups: effects of bars

Abstract

Aims. We explore properties of barred active spiral galaxies in groups and clusters selected from the Sloan Digital Sky Survey data release 7 (SDSS-DR7), with the aim of assessing the effects of bars on active galactic nuclei (AGN) and the role of the high density environment. Methods. We identified barred active galaxies that reside in groups and clusters by cross-correlating the total barred AGN sample with the SDSS-DR7 group catalog. With the goal of providing a suitable quantification of the effects of bars, a reliable control sample of unbarred active galaxies in high density environments with similar redshift, magnitude, morphology, and bulge size distributions was also constructed. Results. We found that the fraction of barred AGN galaxies in groups and clusters (≈38%) is higher than those in the total barred AGN sample (≈28%), indicating that AGN spiral galaxies in groups are more likely to be barred than those in the field. We also found that barred AGN galaxies are more concentrated towards the group centers than the other unbarred AGN group members. In addition, barred AGN host galaxies show an excess of population dominated by red colors, with respect to the control sample, suggesting that bars produce an important effect on galaxy colors of AGN hosts. The groups of AGN galaxies with and without bars show similar virial masses; however, the host groups of the barred AGN exhibit a larger fraction of red colors than the host groups of the corresponding unbarred active galaxies in the control sample. Color-magnitude relations of both host groups of AGN differ significantly: the host group colors of barred active galaxies display distributions spreading toward red populations, at the same (M r ) Group , with respect to the host groups of the unbarred AGN objects. This trend is more significant in less massive groups than in groups with M Virial > 10 13.5 M . Barred active galaxies show an excess of nuclear activity compared to galaxies without bars in the control sample. We found that barred active galaxies located farther from the group-center have stronger Lum [OIII], while the nuclear activity in AGN galaxies without bars remain approximately constant with the group-centric distance. In addition, for both AGN samples, nuclear activity increases in bluer host groups however, barred active objects systematically show higher Lum [OIII] values, irrespective of the global group colors. Our findings suggest that the efficiency of bars to transport material towards the more central regions of the AGN galaxies in high density environments reveals an important dependence on the localization of objects within the group/cluster and on the host group colors.

Automated bar detection in local disk galaxies from the SDSS

“…Nevertheless the bar fraction versus mass relation, along with the well known color-mass relation (Consolandi et al, 2016), implies that there is an higher fraction of bars among more massive galaxies with redder total colors, although we stress that these are still star forming spiral galaxies. This is still consistent with previous works such as the one of Masters et al (2011), Alonso et al (2013), Alonso et al (2014) who consistently find an increasing barfraction in redder galaxies. I found a difference between the bar fraction evaluated among all LTGs (ty¿1) and the one that embraces lenticulars.…”

“…If and how the bar fraction evolves across the cosmic time is still under debate (Jogee et al, 2004;Sheth et al, 2008) as well as the exact determination of the dependence of the bar frequency on stellar mass (especially at the faint end of the mass function) and on galaxy environment (Thompson, 1981;Marinova et al, 2012;Skibba et al, 2012;Lansbury et al, 2014;Alonso et al, 2014). For example, Masters et al (2012), Skibba et al (2012), Méndez-Abreu et al (2012), Gavazzi et al (2015) all consistently report a bar fraction that increases with increasing mass.…”

The Relative Role of Bars and Environments in AGN Triggering

“…They tend to have a less luminous AGN and red color (Kim et al 2020a, for details). Alonso et al (2014) found that the enhancement of nuclear activity is notable in barred active galaxies located in higher-density environments using a massive galaxy sample, consistent with our result.…”

Is the cluster environment quenching the Seyfert activity in elliptical and spiral galaxies?

“…It is worth noting that studies as the above implying that different AGN types do not interact in the same way with their environment represent potential issues to the so-called unification AGN model (Antonucci 1993;Urry & Padovani 1995), which suggests that all AGN are the same type of object viewed from a different angle. Alonso et al (2014) show that spiral galaxies hosting AGN in groups are more likely to be barred than their counterparts in the field. Similar results were presented by Coelho & Gadotti (2011), who found twice as many AGN among barred galaxies, as compared to their unbarred counterparts, for low mass bulges.…”