A greenish glow from a remote galaxy is providing astronomers with a glimpse into star formation in the early days of the universe, hinting at new cosmic mysteries waiting to be explained.
As Sky & Telescope reported, a team of astronomers used the Atacama Large Millimeter/submillimeter Array, or ALMA, located in Chile, to detect oxygen gas in a galaxy nearly 13.3 billion light years away. Since looking across such cosmic distances is also looking back in time, the galaxy is being seen as it was about 550 million years after the Big Bang.
A Light in the Dark
The green glow indicates the presence of oxygen — making the ALMA observations the earliest point in time at which astronomers have detected individual elements — but it is more than that. While we often associate detecting oxygen with the search for life, oxygen is also important for another reason: It was created in stars, said Sky and Telescope.
The early universe, according to Sky & Telescope, was “pristine;” it contained only hydrogen and helium, elements created in the Big Bang. Oxygen only appeared later, cooked up by nuclear reactions inside early stars. Some of these stars later blew up in supernova explosions that spread the oxygen out across space.
When we detected oxygen in the early universe, the time period that NASA described as the dark ages of the universe had already ended. The first stars had formed, produced oxygen and released it into space by exploding.
For this oxygen to be already present in sufficient quantities for ALMA to detect at a time 550 million years after the Big Bang, Sky & Telescope noted that the earliest star formation must have taken place even earlier, when the universe was only about 250 million years old.
Simulations, Complications and Cosmic Mysteries
Every new discovery pulls on the threads of our understanding, opening up new mysteries. The team that detected oxygen with ALMA also examined the same galaxy, designated MACS1149-JD1, with the Hubble and Spitzer Space Telescopes. And what they found was a discrepancy, said Sky and Telescope.
The stars that produce oxygen and later explode are massive and bright. Galaxies have a much larger number of fainter stars. The observations confirm this. But it turns out that, based on computer simulations, MACS1149-JD1 ought to have more bright stars than it does, according to Sky & Telescope.
Contrary to our simulations, noted Sky & Telescope, star formation seems to have started out strong, then slowed down to a comparative trickle before picking up again.
One possibility, added Sky & Telescope, is that a supermassive black hole was disrupting star formation in the galaxy. This is not the only time, as we’ve reported, that black holes have figured in our understanding of the early universe. Likewise, we’ve noted that an ancient star formation is offering insight into one of the greatest of cosmic mysteries, dark matter.
The early universe was filled with surprises. The more we discover, the more we find that calls for further exploration — an ongoing series of adventures that create their own sequels.