Stellar nuclei and inner polar disks in lenticular galaxies

TL;DR

This study investigates the properties of stellar nuclei and inner polar disks in nearby lenticular galaxies, revealing a higher-than-expected frequency of inner polar disks and suggesting similar formation histories across different galaxy components.

Contribution

It provides new statistical insights into the prevalence of inner polar disks and their stellar populations in S0 galaxies using integral-field spectroscopy and velocity field analysis.

Findings

Inner polar disks are present in about 10% of nearby S0 galaxies.

Nuclear stellar populations in polar ring hosts are similar to those in the entire S0 sample.

Seven new cases of inner polar disks were identified.

Abstract

I analyze statistics of the stellar population properties for stellar nuclei and bulges of nearby lenticular galaxies in different environments by using panoramic spectral data of the integral-field spectrograph SAURON retrieved from the open archive of Isaac Newton Group. I estimate also the fraction of nearby lenticular galaxies having inner polar gaseous disks by exploring the volume-limited sample of early-type galaxies of the ATLAS-3D survey. By inspecting the two-dimensional velocity fields of the stellar and gaseous components with running tilted-ring technique, I have found 7 new cases of the inner polar disks. Together with those, the frequency of inner polar disks in nearby S0 galaxies reaches 10% that is much higher than the frequency of large-scale polar rings. Interestingly, the properties of the nuclear stellar populations in the inner polar ring hosts are statistically the same as those in the whole S0 sample implying similar histories of multiple gas accretion events from various directions.