Astronomers' long search for a cluster of dwarf galaxies considered the building blocks of bigger galaxies has found an exciting answer.
In a breakthrough, a team of astronomers, with the help of data from the Sloan Digital Sky Survey (SDSS) and optical telescopes, discovered seven distinct groups of dwarf galaxies getting ready for a merger to form bigger galaxies like the Milky Way.
Merger Of Dwarf Galaxies
The discovery affirmed the long-held belief that many mature galaxies of today are formed by the merger of smaller galaxies, billions of years ago. So far, astronomers were scouting for evidence of such a merger of dwarf galaxies, but it was not coming up.
The findings have been published in Nature Astronomy.
"We know that to make a large galaxy, the universe has to bring together many smaller galaxies," said Sabrina Stierwalt an astronomer with the National Radio Astronomy Observatory (NRAO) and University of Virginia.
The spotting of dwarf galaxy clusters also strengthened a theory that big galaxies such as Milky Way are formed by the amalgamation of smaller galaxies and they have a high presence of dark matter.
In terms of size, dwarf galaxies area almost 1,000 times smaller than mighty galaxies like the Milky Way.
Stierwalt expressed joy that for the first time, an example of such a merger process has been discovered when the entire population of dwarf galaxies was bound together in the same neighborhoods. They were spotted at a distance between 200 million and 650 million light years away from Earth.
What distinguished them was, unlike Milky Way, these dwarfs have stopped giving birth to new stars.
"We suspect these groups are gravitationally bound and thus will eventually merge to form one larger, intermediate-mass galaxy," added Stierwalt.
Quest for Dark Matter
Space scientists consider dwarf clusters to be the hub of dark matter, which is the mysterious substance accounting for a quarter of the Universe yet perceived by the gravitational pull that is felt on other objects in space.
When compared to dark matter, the visible matter is only just five percent of the Universe.
Dwarf galaxies, compared to larger galaxies tend to have "a lot more dark matter," explained Stierwalt. The gravitational force from dark matter holds the clusters together.
Another reason for the preponderance of dark matter in dwarfs is that they have very little debris of gas and dust, unlike bigger galaxies. Astronomers are also searching for the elusive dark matter using gamma-ray detecting telescopes hoping that those particles might be producing gamma rays upon decay.
Aftermath Of Bing Bang
The new discovery also bolsters the theory after the Big Bang of some 13.7 billion years ago, many smaller things conjoined to form bigger entities.
But that remained hypothetical as evidence based on observations were not available, Stierwalt explained.
Adding to the problem is the inability to see dwarf galaxies. Only the Magellanic Clouds are visible to the naked eye.
Stierwalt said the independent groups of low-mass galaxies like the ones found out can reveal the possible mechanism for larger ones as the Milky Way.
