June 6 () –
Astronomers have confirmed that the huge tail of superheated gas left behind by a group of galaxies plunging into the Coma galaxy cluster is the best known.
This queue has, in fact, 1.5 million light-years across, or hundreds of thousands of times the distance between the Sun and the nearest starmaking it the longest tail ever seen behind a galaxy group.
In their research, they have also used it to gain a deeper understanding of how galaxy clusters, some of the largest structures in the universe, grow to their enormous sizes, reports NASA.
Astronomers trained NASA’s Chandra X-ray Observatory on the NGC 4839 group of galaxies. Galaxy groups are collections of about 50 or fewer galaxies that are held together by gravity. Galaxy clusters are even larger and can contain hundreds or thousands of individual galaxies.
Both galaxy clusters and groups of galaxies are enveloped by enormous amounts of hot gas that are best studied with X-rays. These pools of superheated gas, though extremely thin and diffuse, account for a significant portion of the mass in clusters of galaxies. galaxies and are crucial to understanding these systems.
NGC 4839 lies near the edge of the Coma galaxy cluster, one of the largest known clusters in the universe, about 340 million light-years away. As NGC 4839 moves toward the center of the Coma Cluster, hot gas from the galaxy group is blown away by its collision with the cluster gas. This results in a tail forming behind the galaxy group.
The image on the left shows an X-ray view of the Coma galaxy cluster taken with ESA’s (European Space Agency) XMM-Newton (blue), along with optical data from the Sloan Digital Sky Survey (yellow). The NGC 4839 group of galaxies is at the bottom right of that image. The box on the right is the Chandra image (purple) of the region outlined by the square. The head of NGC 4839’s tail is on the left side of the Chandra image and contains the brightest galaxy in the group and the densest gas. The tail is dragged to the right. (The Chandra image has been rotated so that North is about 30 degrees to the left of vertical.)
The current glow of the tail gives astronomers a special opportunity to study the physics of the tail gas before it mixes with the hot gas of the cluster and becomes too faint to study. The gas in the tail behind NGC 4839 finally it will merge with the large amount of hot gas already present in the Coma Cluster.
Using the Chandra data to analyze the gas in front of the galaxy group, the researchers found a shock wave, similar to the sonic boom of a supersonic aircraft, showing that NGC 4839 is traveling at approximately 4.5 million kilometers per hour through of the galaxy cluster.
They also studied the amount of turbulence in the tail gas. For a familiar analogy, turbulence describes the irregular movements of air in our atmosphere that can cause bumpy rides on airplanes. They encountered a slight amount of turbulence, which implies that heat conduction in NGC 4839 is low.
