“Dark” celestial object turned out to be a fertile young galaxy

Mysterious and very distant object, in Universe how it was 2 billion years after Big Bang, was finally characterized in a study published in Astrophysical journal.

An extremely distant celestial body in a still young universe, one-sixth the size of the current one. The object is so dark that it is almost invisible to even the most sophisticated instruments. Its nature has long been a subject of controversy, but thanks to research carried out with the ALMA interferometer, the research group of the International School for Advanced Study (SISSA) in Italy, led by Professor Andrea Lapi, which investigates the formation and evolution galaxiesFinally, it was possible to determine its main properties.

What was found

Compact and with lots of interstellar dust, it is galaxy young, which forms stars about 1000 times faster than Milky Way. Description of this galaxy it will be useful to learn more about this very distant object and indicate new approaches to the study of other “dark” celestial bodies.

” galaxies the true mines of information about the past and future evolution of our universe are very far away,” explains first author Marika Giulietti, who studies astrophysics and cosmology at SISSA, in a statement.

“However, studying them is a rather difficult task. They are very compact and therefore difficult to observe. Also, because of the distance, we get very weak light from them. The reason for this obscuration is the massive presence of interstellar dust, which intercepts visible light from young stars and makes it difficult to detect with optical instruments, and also reradiates it at longer wavelengths, where it can only be observed with powerful interferometers in the (sub)millimeter and radio wave bands. .

These dark bodies are not particularly rare: “In recent years,” Giulietti explains, “a few galaxies especially obscured distant ones that appear completely invisible to even the most powerful optical instruments, such as the Hubble Space Telescope.”

How could this be observed?

The tool used in these cases is the so-called gravitational lens, a solution with great scientific potential. The principle is simple: general relativity causes the nearest objects in space, which have a large mass, to distort light from more distant sources that are perfectly aligned with them.

Giulietti continues: “In this way, large celestial bodies act like a kind of huge cosmic lens that makes galaxies “In the background” they appear larger and brighter, allowing them to be identified and studied.” In the last decade, many observing programs have been carried out using this approach. “To date, about a hundred have been discovered, but there could be many. more.” .

It was during one of these studies, Giulietti says, that the main object of the current study was identified: “It was a very special celestial body. It is very bright and potentially subject to lensing, but this only happens at certain wavelengths.” Observations made with SOULa state-of-the-art submillimeter interferometer located in Chile’s Atacama desert has allowed us to characterize it.”

“We studied this peculiar object by adopting certain codes that allowed us to restore the original shape of the background source, as well as understand some of the properties of the lens itself. The observations have also provided valuable information about the gas content of this source, and we are able to determine how it is distributed.”

“Our analysis showed that this object is very compact, presumably young, and is forming stars at an extremely high rate. In the future, the James Webb Space Telescope will reveal much more about this galaxy than only it can do at the moment. “. (Europe Press)

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