Researchers compact elliptical galaxies have discovered 11 runaway galaxies that have escaped from their previous galaxies.
There are many other ‘runaways’ already discovered by scientists. These include cosmic entities such as planets, stars and even a star cluster. For an object to be ejected from its cosmic home, it needs to move at a speed greater than its escape velocity (which is approximately 6 million miles per hour).
“These galaxies are facing a lonely future, exiled from the galaxy clusters they used to live in,” said astronomer Igor Chilingarian in a statement.
Chilingarian is with the Harvard-Smithsonian Center for Astrophysics and Moscow State University, and also the main author of a paper explaining the rogue galaxies appearing in Science.
Along with his co-author, Ivan Zolotukhin, Chilingarian used public data archives from the Sloan Digital Sky Survey and the GALEX satellite for searching compact elliptical galaxies.
Before the research, only 30 compact ellipticals have been discovered and Chilingarian and Zolotukhin managed to increase that number to 200 galaxies. Among them were 11 completely isolated galaxies and too far from any galaxy or galactic cluster for association.
According to prior theories, the isolated galaxies should not exist. Scientists thought that the compact ellipticals were once large galaxies, stripped of their stars through collisions with even larger galaxies. So, compact ellipticals were expected to be located near very large galaxies.
“The first compact ellipticals were all found in clusters because that’s where people were looking. We broadened our search, and found the unexpected,” said Zolotukhin.
The team believes that the rogue galaxies can be the outcome of three galaxy collision: A compact elliptical is stripped of its stars by a bigger galaxy and an even larger galaxy collides with the pair, throwing the tiny galaxy free of its gravitational pull on either of the larger ones.
Researchers say that the findings represent a victory for the Virtual Observatory (VO). Coordinated by The International Virtual Observatory Alliance or IVOA, the VO is a project for collecting data from astronomical surveys accessible to researchers for finding useful info and hopefully result in finds not anticipated by those who originally listed the data.
“The IVOA now comprises 20 VO programs from Argentina, Armenia, Australia, Brazil, Canada, Chile, China, Europe, France, Germany, Hungary, India, Italy, Japan, Russia, South Africa, Spain, Ukraine, the United Kingdom, and the United States and an inter-governmental organization (ESA)” according to the website.