NGC 2207/IC 2163: A Grazing Encounter with Large Scale Shocks

TL;DR

This study uses multi-wavelength observations to analyze large-scale shock fronts, star formation, and nuclear activity in the interacting galaxy pair NGC 2207/IC 2163, revealing complex shock phenomena and a possible low-luminosity AGN.

Contribution

It provides a detailed multi-wavelength analysis of shock fronts and nuclear activity in NGC 2207/IC 2163, highlighting new shock features and evidence of a low-luminosity AGN.

Findings

Identification of two types of large-scale shock fronts.

Detection of a radio supernova in NGC 2207.

Evidence of a low-luminosity, highly absorbed AGN.

Abstract

Radio continuum, Spitzer infrared, optical and XMM-Newton X-ray and UVM2 observations are used to study large-scale shock fronts, young star complexes, and the galactic nuclei in the interacting galaxies NGC 2207/IC 2163. There are two types of large-scale shock fronts in this galaxy pair. The shock front along the rim of the ocular oval in IC 2163 has produced vigorous star formation in a dusty environment. In the outer part of the companion side of NGC 2207, a large-scale front attributed to disk or halo scraping is particularly bright in the radio continuum but not in any tracers of recent star formation or in X-rays. This radio continuum front may be mainly in the halo on the back side of NGC 2207 between the two galaxies. Values of the flux density ratio S(8 um)/S(6 cm) of kpc-sized, Spitzer IRAC star-forming clumps in NGC 2207/IC 2163 are compared with those of giant H II regions in M81. We find evidence that in 2001 a radio supernova was present in the core of feature i, a mini-starburst on an outer arm of NGC 2207. X-ray emission is detected from the NGC 2207 nucleus and from nine discrete sources, one of which corresponds to SN 1999ec, and another may be a radio supernova or a background quasar. The X-ray luminosity and X-ray spectrum of the NGC 2207 nucleus suggests it is a highly absorbed, low luminosity AGN.