A galaxy some 3 billion light-years from Earth is fading away the darkness of universe after 400 million years.
NASA-funded research team with grant number 12886 at the Johns Hopkins University have discovered that a compact galaxy named J0921+4509 is producing massive, young stars at a very fast rate. The streams of intense UV rays is said to have a close resemblance to the light formed during the birth of the universe. Consisting of thick, dense cold gas, the cover stretches across a galaxy like a blanket. The galaxy emits 21 percent of the Ultraviolet rays into deep space.
“That’s quite high,” says astronomer Brian Siana of the University of California, Riverside. “This is roughly the fraction that we think all galaxies in the early universe had to have in order to ionize the hydrogen in the intergalactic medium.”
“It’s like the ozone layer, but in reverse,” said Sanchayeeta Borthakur, an astronomer from the Johns Hopkins University said.
“The ozone layer protects us from the sun’s radiation but we want the gas cover the other way around. The star-forming regions in galaxies are covered with cold gases, so the radiation cannot come out. If we can find out how the radiation gets out of the galaxy, we can learn what mechanisms ionized the universe.”
The protons and electrons scattered after the Big Bang began to cool, forming the first atom’s of hydrogen after thousands of years and it formed UV rays absorbing, hydrogen walls and cosmic dust clouds. These walls prevented any light from releasing causing the long darkness era of the universe.
This radiation eventually got more powerful resulting in re-ionization of the hydrogen, due to which electrons break out from the hydrogen atoms causing large amount of energy that brightened the universe ending up the dark universe period. The radiation that broke the electrons is believed to come from stellar births but astronomers are still unsure of what exactly happened.
“The star forming regions in galaxies are covered with cold gases so the radiation cannot come out. If we can find out how the radiation gets out of the galaxy, we can learn what mechanisms ionized the universe,” added Borthakur.
Researchers have been in a long stretched quest of finding a “holey” galaxy to study how star-produced radiation plays a role in ionization process.
The researchers located the precise galaxy with the help of radiation leak measurement method and Cosmic Origin Spectrograph aboard the Hubble Space Telescope. According to a statement, the team credits “a combination of unusually strong winds, intense radiation and a massive, highly star-forming galaxy” for the validity of the indicator.
“The confirmation of the indicator is key,” Borthakur said. “The implications are now people can use this indicator to study distant galaxies at longer wavelengths.”
Borthakur also said, ”The high density of stars in a compact region in J0921+4509 results in an explosion-like feedback that is able to create the gaps.”
Borthakur, Timothy Heckman, the Dr. A. Hermann Pfund Professor and director of the Center for Astrophysical Sciences at Johns Hopkins wrote the paper published in the journal science on Oct 9, The study co-authors were Claus Leitherer from the Space Telescope Science Institute and Roderik Overzier from the Observatorio Nacional in Rio de Janeiro, Brazil.