Dawn of the universe might have been bursting with galaxies now hidden by dust

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Studying galaxies in the night sky is an exercise in time travel, because the light we see reflects what things looked like in the past, sometimes even billions of years ago. So studying the galaxies farthest from us can give us an idea of ​​what the early universe was like—and if the two newly discovered galaxies are any indication, the cosmic dawn may be much more alive than anyone realizes.

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New galaxies were discovered by accident. Typically, when astronomers go looking for really old objects in space, they look for those that are very red-shifted, because objects moving away from the observer effectively pull up the light they are in. emit at longer wavelengths, thus appearing red. What astronomers don’t usually do, however, is study what appears to be empty space.

Now, after the unexpected emission that appears from nowhere beside red-shifted galaxies astronomer Yoshinobu Fudamoto was observing with the Atakama Large Millimeter/submillimeter Array (ALMA), which may have to change.


All that empty space may be filled with the oldest galaxies in the universe, covered with cosmic dust.

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Fudamoto, from Waseda University and the National Astronomical Observatory of Japan, and an international team of astronomers who helped confirm their findings, explained in a paper published this week in the journal Nature that the two new galaxies show what we learned about the early universe. Thought, lifted him up.

“These new galaxies were discarded not because they are extremely rare, but simply because they are completely covered with dust,” Fudamoto said.

And since astronomers used to believe that galaxies in the early universe were generally not blocked by cosmic dust, “it is possible that we are missing one out of every five galaxies in the early universe by now, Fudamoto said.

The problem with dust is that it can absorb UV radiation, which telescopes such as the Hubble Space Telescope use to find objects in space that may not be detectable in the visible light spectrum.

Astronomers have begun to use telescopes such as ALMA, however, to probe sub-millimetre wavelengths of light that have shifted away in the red part of the spectrum, which allows them to absorb UV light from dust. Allows the detection of objects obscured by dust.

Now, they may have to start using these submillimeter telescopes in blind surveys of the night sky to see what else may have been missed.

Analysis: The James Webb Space Telescope is becoming more important by the day

Given our current abilities, there is only so much we can see or do, but soon we expect to see a major upgrade in our ability to see in the night sky.

The James Webb Space Telescope (JWST), currently on its way to French Guiana in preparation for its December 2021 launch, is the most advanced space telescope ever built.

When it is located about 1.5 million km from Earth, it will have the most unobstructed view of the universe of any telescope we have built, giving its 18-meter mirror array more light to work with.

It’s also built from the ground specifically to detect infrared light, which Hubble largely can’t—which is why it can make all those dusty-obscured galaxies disappear—leading to our early universe. It becomes necessary for the study.

“Completing our initial galaxies census with currently missing galaxies Galaxies obscured by dust, such as the one we found this time, will be one of the main objectives of the JWST and ALMA surveys in the near future, said Pascal Osch of the University of Geneva, one of the paper’s co-authors.

Add one more to the list of things JWST will have to do once it gets there. no pressure.

  • NASA’s incredible plans for six space telescopes ‘better than Hubble’

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