A Cosmic Intruder Grabbed Hot Gas From This Galaxy Group

NGC 5044 as seen by XMM-Newton. Astronomers say they are able to see hot gas moving in this galaxy because of an interaction with another galaxy millions of years ago. Credit: E. O’Sullivan & ESA

So galaxy group NGC 5044 was just sitting quietly by itself a few million years ago when galaxy NGC 5054 decided to pass right through it. That close encounter finished long ago, but the ricochet is still visible in telescopes as astronomers spotted hot gas rippling through the host galaxy.

“Galaxies are social beasts that are mostly found in groups or clusters – large assemblies of galaxies that are permeated by even larger amounts of diffuse gas. With temperatures of 10 million degrees or more, the gas in galaxy groups and clusters is hot enough to shine brightly in X-rays and be detected by ESA’s XMM-Newton X-ray observatory,” the European Space Agency stated.

“As galaxies speed through these gigantic cauldrons, they occasionally jumble the gas and forge it into lop-sided shapes. An example is revealed in this composite image of the galaxy group NGC 5044, the brightest group in X-rays in the entire sky.”

Fresh observations from XMM-Newton (in blue) are visible in this composite image with other pictures from the Wide-field Infrared Survey Explorer, the Digitized Sky Survey (optical) and Galex (near-ultraviolet).

Publication of this research was accepted in MNRAS and is currently available on prepublishing site Arxiv. The lead author is Ewan O’Sullivan, a visiting scientist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.