A treasure trove of molecules has been discovered in two galaxies we saw 12 billion years ago, revealing information about how stars formed in the ancient realm.
One of the distant galaxies, APM 08279+5255, is home to a quasar—an active supermassive black hole at its core that devours vast amounts of gas—while the other, NCv1.143, is a more “normal” one. of galaxies. However, both are thought to be forming stars at an astonishing rate, hundreds of times more than the Milky Way is currently producing.
Astronomers used France’s NOEMA (Northern Extended Millimeter Array) to target the two galaxies. NOEMA is capable of detecting millimeter and submillimeter radio waves. Fascinatingly, a team led by Chentao Yang of Chalmers University of Technology in Sweden detected the emission of up to 13 different molecules in the two galaxies.
“We saw parts of the electromagnetic spectrum that are difficult to observe in nearby galaxies,” Yang said in a press statement. “But because of the expansion of the universe, the light from distant galaxies like this is shifted to longer wavelengths, and we can observed with radio telescope [at] Submillimeter [wavelengths]”.
The discovery constitutes the largest collection of molecules ever detected in a galaxy at such an extreme distance (the galaxy is now about 20 billion light-years away, and is growing even further due to the expansion of the universe).
The 13 different types of molecules detected included carbon monoxide, carbon monosulfide, cyano (a free radical is a molecule with an unpaired electron in the outer shell of one of its constituent atoms), formyl cation (a cation is a positively charged ion ), hydrogen cyanide, hydrogen isocyanide, nitric oxide and water. Yang’s team also detected five molecules never seen in the early universe: cyclopropene (a highly reactive organic molecule also found on Saturn’s moon Titan), diazenium (made from molecular nitrogen and hydrogen ion), the radical ethynyl group of organic molecules, the hydronium ion (formed from water molecules and hydrogen ions), and the methylene radical (a highly reactive organic molecule).
All of these molecules are commonly found in the interstellar gas of our galaxy, and each provides clues about the environment in which they are found—the environment in which we see massive numbers of stars forming.
“We know that these galaxies are massive star factories, perhaps one of the largest in the universe,” Yang said.
The research team also found that the quasars in APM 08279+5255 contain more excited molecular gas at higher temperatures and densities than the entire NCv1.143, which may be the result of activity around the quasar’s black hole. Its molecular abundance is similar to galaxies with active black holes in the modern universe. Likewise, NCv1.143’s molecular inventory is similar to local starburst galaxies, which are simply galaxies that birth large numbers of stars, such as the Cigar Galaxy in the constellation Ursa Major (Messier 82). The chemical composition of these types of galaxies appears to have existed 12 billion years ago.
But not everything is created equal. The intensity of emissions from some molecules, such as carbon dioxide, combined with the extreme conditions of the star-forming gases of both galaxies, shows what is known as a “top-heavy initial mass function.” The initial mass function (IMF) describes how many stars of a given mass can form, with low-mass stars being more common than high-mass stars. A top-heavy IMF means that more massive stars could be formed in the early universe than can be formed today. Not only would this explain why the galaxies in the early universe detected by the James Webb Space Telescope were brighter than expected – they contained larger, brighter stars – but it also suggests the presence of more massive stars that exploded as supernovae accelerated and exploded. The development of chemistry in these galaxies distributed heavy elements throughout space.
“The most remarkable galaxies in the early universe are finally able to tell their story through their molecules,” said co-author Pierre Cox of Sorbonne University in France.
The findings were published on December 14 in the journal Astronomy and Astrophysics.
Originally published on Space Network.
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