Leaky Galaxies Shed Light on the Universe

Scientists are focusing on large, star-forming galaxies, whose radiation leaks are shedding light on the beginnings of the Universe as the first stars came into existence, new research says.

Some star-forming galaxies have punctured holes in their cold gas cover, through which radiation can escape. But the details behind how radiation seeps through these leaky galaxies have long puzzled scientists.

Consisting of thick, dense cold gas, the cover stretches across a galaxy like a blanket. While an effective tool for star formation, this cover presents a challenge for astrophysicists hoping to learn how the radiation that stars produce could be used in the ionization process. For decades, scientists have been in search for such a leaky galaxy, hoping to better understand the mysteries of the Universe.

"It's like the ozone layer, but in reverse," Sanchayeeta Borthakur, a research scientist at the Johns Hopkins University, said in a statement. "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 reionization of the Universe took place several hundred thousand years after the Big Bang. Protons and electrons began to bond and form neutral hydrogen atoms, which then collapsed on themselves, lending formation to the Universe's first stars and galaxies.

Leaky galaxies are the key to understanding the reionization process, which is core to the history of the cosmos, but finding these galaxies is easier said than done.

Using observations from the Cosmic Origin Spectrograph onboard the Hubble Space Telescope, scientists finally found the diamond in the rough. Galaxy NGC 300 is located about seven million light-years away in the constellation Sculptor. In the study, the researchers credit a combination of unusually strong winds, intense radiation and a massive, highly star-forming galaxy for proving the validity of the leaky, spiral galaxy.

This method can not only measure radiation leaks, but also sort out what gas is present in the galaxy and also accurately measure the percentage of holes in the gas cover.

The findings were published in the journal Science.