The Arp 220 merger on kpc scales

TL;DR

This paper investigates the molecular gas distribution and merger dynamics of Arp 220 on kiloparsec scales using multi-epoch CO observations and simulation modeling, revealing extended emission and merger parameters.

Contribution

It provides a detailed analysis of the molecular gas in Arp 220's nuclei and models the large-scale merger with new CO data and Identikit simulations.

Findings

Extended CO emission detected beyond the nuclei.

Merger model suggests a 1:2 mass ratio and ~6x10^8 years duration.

Indications of emission ~10" south, north, and west of nuclei.

Abstract

For the first time we study the Eastern nucleus in greater detail and search for the more extended emission in the molecular gas in different CO line transitions of the famous ULIRG Arp 220. Furthermore we present a model of the merger in Arp 220 on large scales with the help of the CO data and an optical and near-infrared composite HST image of the prototypical ULIRG. Using the Plateau de Bure Interferometer (PdBI) we obtained CO(2-1) and (1-0) data at wavelengths of 1 and 3 mm in 1994, 1996, 1997 and 2006 at different beam sizes and spatial resolutions. The simulations of the merger in Arp 220 were performed with the Identikit modeling tool. The model parameters that describe the galaxy merger best give a mass ratio of 1:2 and result in a merger of ~6x10^8 yrs. The low resolution CO(1-0) PdBI observations suggest that there are indications for emission ~10" towards the south, as well as to the north and to the west of the two nuclei.