Astronomers studying a cluster of still-forming protogalaxies seen as they were more than 10 billion years ago have found that a giant galaxy in the center of the cluster is forming from a surprisingly-dense soup of molecular gas.
“This is different from what we see in the nearby Universe, where galaxies in clusters grow by cannibalizing other galaxies. In this cluster, a giant galaxy is growing by feeding on the soup of cold gas in which it is submerged,” said Bjorn Emonts of the Center for Astrobiology in Spain, who led an international research team.
The scientists studied an object called the Spiderweb Galaxy, which actually is not yet a single galaxy, but a clustering of protogalaxies more than 10 billion light-years from Earth. At that distance, the object is seen as it was when the Universe was only 3 billion years old. The astronomers used the Australia Telescope Compact Array (ATCA) and the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to detect carbon monoxide (CO) gas.
The presence of the CO gas indicates a larger quantity of molecular hydrogen, which is much more difficult to detect. The astronomers estimated that the molecular gas totals more than 100 billion times the mass of the Sun. Not only is this quantity of gas surprising, they said, but the gas also must be unexpectedly cold, about minus-200 degrees Celsius. Such cold molecular gas is the raw material for new stars. … (NRAO)