London:
A giant galaxy forming from a dense cold soup of molecular gas has been spotted by a team of scientists, including one of Indian origin.
Bjorn Emonts of the Centre for Astrobiology in Spain, who led the study, said usually the galaxies in clusters in the nearby universe grow by cannibalising other galaxies. But in case of this newly found galaxy, the process is different.
“This is different from what we see in the nearby Universe, where galaxies in clusters grow by cannibalising other galaxies,” said Bjorn Emonts.
The giant galaxy is instead growing from the soup of cold gas, where it is submerged.
“In this cluster, a giant galaxy is growing by feeding on the soup of cold gas in which it is submerged,” said Emonts.
An object called Spiderweb Galaxy was studied by the scientists. The Spiderweb Galaxy is actually not a single galaxy but a clustering of protogalaxies more than 10 billion light-years from Earth.
At that distance, the Spiderweb Galaxy is seen as it was when the Universe was only 3 billion years old.
Australia Telescope Compact Array (ATCA) and the National Science Foundation’s Very Large Array (VLA) to detect carbon monoxide (CO) gas were used by the astronomers for this study.
CO gas presence points out at the presence of larger quantity of molecular hyderogen, which is much more difficult to detect. According to the astronomers estimate, the molecular gas totals more than 100 billion times the mass of the Sun.
They said that this quantity of gas surprised them and it must also be unexpectedly cold, about minus-200 degrees Celsius. Such cold molecular gas is the raw material for new stars.
The supernova explosions of earlier generations of stars enriched the gas due to the presence of CO in it. The cores of stars that later exploded are the places where the carbon and oxygen in the CO formed.
Another surprise was the total extent of the gas, and the VLA observations, which were much more narrowly focused, reveal the ATCA observations.
Most of the cold gas was discovered between the protogalaxies instead of within them.
“This is a huge system, with this molecular gas spanning three times the size of our own Milky Way Galaxy,” said Preshanth Jagannathan, of the US National Radio Astronomy Observatory (NRAO).
Rapid star formation is ongoing across most of the region occupied by the gas, earlier observations of the Spiderweb, made at ultraviolet wavelengths, have indicated.
“It appears that this whole system eventually will collapse into a single, gigantic galaxy,” Jagannathan said.
“These observations give us a fascinating look at what we believe is an early stage in the growth of massive galaxies in clusters, a stage far different from galaxy growth in the current Universe,” said Chris Carilli of NRAO.
The study was published in the journal Science.
(With inputs from PTI)
