Unveiling the nature of polar-ring galaxies from deep imaging

TL;DR

This study uses deep optical imaging to analyze the structure and formation mechanisms of polar-ring galaxies, revealing faint tidal features and supporting galaxy merging as the primary formation process.

Contribution

It provides the deepest images of PRGs to date and offers detailed photometric analysis, highlighting merging and tidal accretion as key formation mechanisms.

Findings

Detection of faint tidal structures around most PRGs

Direct observation of polar ring formation via merging

Evidence supporting galaxy merging as the main formation process

Abstract

General structural properties and low surface brightness tidal features hold important clues to the formation of galaxies. In this paper, we study a sample of polar-ring galaxies (PRGs) based on optical imaging from the Sloan Digital Sky Survey (SDSS) Stripe82 and other deep surveys. We investigate the deepest images of candidates for PRGs to date. We carry out photometric decomposition on the host galaxies and associated polar structures that allows us to derive the structural properties of both components. We are able to detect very faint tidal structures around most PRGs in our sample. For several galaxies, we can directly observe the formation of the polar ring due to merging, which is manifested in debris of the victim galaxy and an arc-like polar structure made up of its material. In a few cases, we can discern signs of tidal accretion. The results obtained indicate that the gravitational interaction and merging of galaxies are the most plausible mechanisms for the formation of polar-ring galaxies.