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Millions-Of-Years-Old Radio Signal Reveals the Most Distant Galaxy of Its Kind

Researchers have succeeded in capturing a signal with the longest retrospective time of all that belongs to a distant galaxy.

Thanks to a phenomenon described by Albert Einstein a century ago, astrophysicists were able to detect a record signal from the farthest distant galaxy of its kind. Until a few decades ago, gravitational lenses lived only in the imagination of researchers, but as technology has advanced, we now know they exist, and not only that, but they can help us detect extremely distant objects.

Hydrogen is one of the most important elements in the Universe since it is believed that after the Big Bang, it was the most abundant element, and later the subatomic particles recombined due to gravity, creating new elements. This is why astrophysicists search for light signatures of atomic hydrogen to find objects very distant from our Solar System and, therefore, ancient.

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With the help of the Giant Metrewave Radio Telescope (GMRT) in India, researchers have succeeded in capturing a signal with the longest retrospective time of all that belongs to a distant galaxy. The latter term refers to the time the light signal takes between emission and detection the signal.

The galaxy SDSSJ0826+5630 is now the most distant object of its type ever detected, with a retrospective time of 8.8 billion years, which means that its atomic hydrogen light signature has been the most distant from Earth detected so far for a galaxy.

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How Did They Manage to Detect the Distant Galaxy?

While it is true that space telescopes are becoming increasingly powerful and open up the possibility of finding a myriad of objects in the cosmos, it is also true that probing deep space is complicated when dealing with such large distances.

This is why astrophysicists are using the alignment of massive objects that create gravitational lenses to get a glimpse into the past. These are phenomena described nearly a century ago by the German physicist Albert Einstein, who predicted that light bends around massive objects in space-time in the same way that light bends as it passes through a lens.

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In that sense, they serve as magnifying glasses of the past by greatly magnifying images of galaxies and other light-emitting objects, which otherwise could not be seen. Through them, several galaxies and stars have been discovered that are magnified by the warping of space-time. As we know, when dealing with such large distances, astrophysicists use the measure of light-years, which refers to the distance that light has traveled for one year and this is the reason why gravitational lenses are said to be windows into the past, as they allow us to look at emissions that occurred millions of years ago.

[Photo: Chakraborty y Roy/NCRA-TIFR/GMRT]

A Signal Different from Previous Ones

The type of signal captured by the GMRT is a radio signal and has been emitted by atomic hydrogen, which is a light wave with a length of 21 centimeters. Long waves are not very energetic, nor is the light intensity, and it is precisely for this reason that it is difficult to detect them at such great distances. Before finding the distant galaxy SDSSJ0826+5630, the record retrospective time was only 4.4 billion years.

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“A galaxy emits different types of radio signals,” says cosmologist Arnab Chakraborty, of McGill University in Canada. “So far, it has only been possible to capture this particular signal from a nearby galaxy, which limits our knowledge to those galaxies closest to Earth.”

Due to the great distance traveled by the radio signal emitted by the distant galaxy and before being intercepted by the GMRT, the emission line expanded in space to 48 centimeters, a phenomenon known to astrophysicists as redshift or redshift, which determines how far away the emission source is.

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Story originally published in Spanish in Ecoosfera

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