Researchers have discovered eleven runaway galaxies; they have been flung out of their homes to wander the universe forever.
Igor Chilingarian, from Harvard-Smithsonian Center for Astrophysics and Moscow State University, who is lead author of the study, said the eleven galaxies will face lonely future, exiled from the galaxy cluster they used to live in.
If the object is moving with the faster velocity than escape velocity, then that object is a runaway.
The speed required for the galaxy to runaway from its cluster is 6 million per hour or 3,000 km per second.
The research team was initially determined to identify new members of a class of galaxies called compact elliptical.
Compact elliptical are tiny blobs of stars which are bigger than star clusters but smaller than a typical galaxy. They span over few hundred light years whereas the Milky Way spans over 100,000 light years across.
Compact elliptical also weigh 1000 times less than a typical galaxy.
At present only 30 compact elliptical galaxies are known and all of them reside in their galaxy cluster.
The study is performed by Chilingarian and Ivan Zolotukin, from L’Institut de Recherche en Astrophysique et Planetologie and Moscow State University, who is the co-author of the study.
Chilingarian and Zolotukhin are set to locate new examples of compact elliptical have sorted through public archives of data from the Sloan Digital Sky Survey and the GALEX satellite.
They have discovered 200 unknown compact elliptical. Eleven among the 200 were found to be completely isolated and far from any galaxy cluster.
Zolotukhin said, “The first compact ellipticals were all found in clusters because that’s where people were looking. We broadened our search, and found the unexpected.”
Theorist thought that the compact galaxies originated from larger galaxies that have been stripped of most of the star through interaction with other bigger galaxy, hence they are expected to found near big galaxies, but they found isolated compact galaxies which is completely unexpected.
They found that they are not only isolated but moving faster than their brethren in clusters.
Chilingarian said, “We asked ourselves, what else could explain them? The answer was a classic three-body interaction.”
A hypervelocity star can be created if a binary star system wanders close to the black hole at the center of the galaxy. One star gets captures while the other is thrown away at tremendous speed.
Similarly, it is believed that a compact elliptical could be paired with the big galaxy that stripped it of its stars, and then a third galaxy blunders into the dance and flings the compact elliptical away, the intruder gets accreted by the remaining big galaxy.
Virtual observatory is a project to make data from large astronomical surveys available to researchers.
The discovery is a success of the project.
Chilingarian said, “We recognized we could use the power of the archives to potentially unearth something interesting, and we did.”
