The visible environment of polar ring galaxies

TL;DR

This study investigates the environments of polar ring galaxies, finding they resemble normal galaxies' surroundings, supporting models of their long-term stability and ancient formation.

Contribution

It provides the first detailed statistical analysis of the environments around polar ring galaxies, including object concentrations and potential past interactions.

Findings

Polar ring galaxies have environments similar to normal galaxies.

No recent interaction signatures are detected around polar rings.

Supports models of long-lived, stable polar rings.

Abstract

A statistical study of the environment around Polar Ring Galaxies is presented. Two kinds of search are performed: 1) a study of the concentration and diameters of all the objects surrounding the Polar Rings, within a search field 5 times the ring diameter. New magnitudes for polar ring galaxies are presented. 2) a search, in a wider field, for galaxies of similar size that may have encountered the polar ring host galaxy in a time of the order of 1 Gyr. Differently from the results of similar searches in the fields of active galaxies, the environment of the Polar Ring Galaxies seems to be similar to that of normal galaxies.This result may give support to the models suggesting long times for formation and evolution of the rings. If the rings are old (and stable or in equilibrium), no traces of the past interaction are expected in their surroundings. In addition, the formation of massive polar rings, too big to derive from the ingestion of a present-day dwarf galaxy, may be easily placed in epochs with a higher number of gas-rich galaxies.