JAKARTA - Astronomers have captured the first picture of an 'invisible galaxy' using Albert Einstein's theory of general relativity.
The celestial body, which formed two billion years after the Big Bang, remains elusive because of its distance and is shrouded in interstellar dust, hiding it from the views of even the most powerful instrument on Earth.
Einstein's theory states that mass distribution can act as a gravitational lens that deflects light, and an Italian team of astronomers uses this idea to see the galactic's invisible 'background'.
The discovery made by research groups from the Sissa school will help reveal more about this galaxy and demonstrate a new approach to studying other 'dark' celestial objects.
The invisible galaxy formed stars about 1000 times the speed of the Milky Way. And it was also very young, considering that the big bang occurred 13.8 billion years ago and was formed two billion years later.
The team used the ALMA telescope (Atacama Large Millimeter/submillimeter Array) in Chile to capture this extraordinary observation.
A very distant galaxy is a real information mine about the past and future evolution of our universe, said the first author of the study, Marika Giulietti, who studied Astrophysics and Cosmology at SISSA. However, studying it is very challenging. They are very compact and therefore difficult to observe.
According to Giulietti, several distant galaxies have been found so closed that they are not visible at all even by optical instruments as strong as the Hubble Space Telescope.
The cause of this fusion is the presence of massive interstellar dust, which blocks visible light from young stars, and makes it difficult to detect with optical instruments, and emits them back at larger wavelengths where it can only be observed with strong interferometers, such as ALMA, said Giulietti, quoted by the Daily Mail.
The interferometer is a state-of-the-art telescope that works by combining two or more light sources to create measurable and analyzed interference patterns.
The observation also provides valuable information about the gas content of this source, and we can determine how its distribution is, said Giulietti. Our analysis shows that this object is very compact, maybe young, and forms stars with very high speeds.
In the future, the James Webb Space Telescope will reveal more about this galaxy, something it can only do right now. The tools used in this case are called gravitational lensing.
The principle is simple: General relativity means space objects closer to us that have a large mass distorting light emanating from a further source that is perfectly aligned with it.
In this way, massive celestial objects act as a kind of very large cosmic lens that makes the 'background' of galaxies appear larger and brighter, allowing them to be identified and studied," said Giulietti.
Over the past decade, many observation programs have been carried out with this approach. About a hundred have been found so far, but maybe much more.
This is a very special celestial body. It is very bright and has the potential to experience lensing, but it only happens at a certain wavelength that is appropriate, perhaps due to the presence of large amounts of interstellar dust. Studying it is very complex," said Giulietti.
Professor SASsi, Andrea Lapi, co-author of the study, concludes by emphasizing the importance of this study. Young, dense distant galaxies, characterized by strong star formation, and largely covered by dust, and possessing a very rich reservoir of molecular gas, are the predecessors of massive quiescent galaxies we see in the local universe, and therefore provide a very valuable insight into the processes leading to the formation and evolution of these structures during the history of the cosmos,'' he said.
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