Astronomers have always considered intergalactic violence to be a part of the process through which large galaxies tend to grow. A new survey suggests that some distant galaxies rip up and devour their smaller galaxy neighbours. Milky Way and Andromeda galaxy are known to be cannibals, spiral and closest to each other.
WHAT HAPPENS DURING THE PROCESS
The gravitational force of the larger galaxy strips away the stars, gas and dark matter from a smaller galaxy, when in close contact. There are several tiny galaxies scattered all around the universe. These merging of galaxies and the tidal interactions are reasons of shaping up all large galaxies.
With the help of the data collected by Anglo-Australian Telescope, New South Wales, a survey was formed. The research was led by Professor Simon Driver, ICRAR and forms a crucial part of the Galaxy and Mass Assembly (GAMA). It took seven years and above 90 scientists to complete the survey.
Dr Aaron Robotham, International Centre for Radio Astronomy Research, released a study in ‘Monthly Notices of the Royal Astronomical Society’, which states that every individual galaxy starts small and creates stars from gas but they get cannibalised by some other large galaxy. The stars move slowly since they lie at the farthest point in their orbit. This makes their tangential and sideways motions to be faster than their radial motion.
He claims that Milky Way is also expected to grow by eating up smaller galaxies rather than collecting gases. Even though, since a long time, Milky Way hasn’t merged with other galaxy but traces of the old smaller galaxies can be seen. It is expected that in four billion years, Milky Way would devour two more dwarf galaxies called Large and Small Magellanic Clouds.
He even stated that Andromeda will end up eating Milky Way since it’s bigger than our galaxy. With the increase in gravity, bigger galaxies pull in smaller galaxies for feeding on them.
THE BOTTOM LINE
Several large galaxies have ceased to make their own stars and instead, feed on smaller galaxies near to them. After analysing the data of 22,000 galaxies, astronomers have noticed that the smaller galaxies tend to make more stars from the gas while massive galaxies can’t make their own stars easily. They grow by eating up other galaxies.
Findings suggest that Milky Way has evolved by eating up other smaller galaxies.