The first light in the Universe may have been released from an early galaxy "leaking" radiation into the developing Cosmos.
Johns Hopkins University astronomers examined large, star forming galaxies in order to study the way radiation can leak through the clouds of cold gas that surrounds all such collections of stars. These covers of cold, dark gas act like a blanket, covering the families of stars, holding in radiation that would otherwise ionize traces of material in intergalactic space.
"It's like the ozone layer, but in reverse. 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," Sanchayeeta Borthakur, assistant research scientist in the Department of Physics and Astronomy at John Hopkins University, said.
Such clouds of gas play an integral role in the creation of new stars. However, they can make it difficult for astronomers to study ionizing radiation produced by distant galaxies. Astronomers have spent decades looking for a "leaky" galaxy, with breaks in the clouds, allowing energy out from within the protective coating.
Galaxy J0921+4509 is a starburst galaxy, a class of structures where the birth of new stars are commonplace. Astrophysicists believe these galaxies mimic many of the same qualities as the first families of stars in the ancient Universe. This collection of stellar families, located roughly three billion light years from the Milky Way, is ripe with star formation, producing stars 33 times faster than the Milky Way. The galaxy also leaks ionizing radiation into space, exhibiting behavior that could have allowed the first electromagnetic energy to travel through intergalactic space.
A few hundred thousand years after the Big Bang, protons and electrons paired up, forming (almost exclusively) hydrogen and helium gases. These atoms were electrically neutral, absorbing any ionizing gas, rendering the Universe completely dark. Roughly a billion years after the birth of the Cosmos, many electrons were once again freed from protons, allowing light to travel through the Universe. Astronomers questioned how this process of reionization could have occurred if such radiation was blocked by galactic clouds.
The galaxy J0921 is 650 light years in diameter, meaning young, active stars are packed closely together. Heating and radiation from the young bodies appear to be pushing on the sides of small holes in the gas, widening the exits.
Investigation of J0921 and how leaky galaxies could have led to the presence of electromagnetic radiation between galaxies was published in the journal Science.
