National Astronomical Observatory of Japan

Multiple Mergers Generate Ultraluminous Infrared Galaxy

| Science

A team of astronomers has concluded that the ultraluminous infrared galaxy (ULIRG) Arp 220 developed from a multiple merger among four or more galaxies. The team’s new imaging data from the Subaru Telescope and optical spectroscopy from the W. M. Keck Observatory revealed two tidal tails that facilitated their analysis of Arp 220’s development. Because Arp 220 is an archetypal or representative ULIRG, the team’s findings facilitate the understanding of ULIRG development in general.

Optical images of Arp 220
Figure 1: Optical images of Arp 220.
Left: Image from the Hubble Space Telescope’s Advanced Camera for Surveys (ACS). (Credit: Hubble Space Telescope) Right: Image from the Subaru Prime Focus Camera (Suprime-Cam). Huge, complex tidal remnants surround Arp 220. (Credit: Ehime University / NAOJ)