Scientists search for the mysterious ‘invisible galaxy’ of the early universe

How would you describe a galaxy that doesn’t want to be seen? You take out a cosmic magnifying glass. A research team led by astrophysics doctoral student Marika Giulietti of the Scuola Internazionale Superiore di Studi Avanzati (Sissa) in Italy published a study on a “very special” galaxy in The Astrophysical Journal this month. In a statement on Tuesday, Sissa described it as a “mysterious and very distant object” and “so dark as to be nearly invisible, even to highly sophisticated instruments.” Intriguing.

The galaxy dates back to just 2 billion years after the Big Bang, which scientists estimate occurred about 13.8 billion years ago. To better understand the galaxy, the team turned to a technique known as gravitational lensing that uses certain massive celestial objects, such as galaxy clusters, as giant lenses to help magnify what’s behind them. The Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile provided the observations. ALMA clued astronomers into previously unknown features of the difficult-to-study galaxy, which is rich in gas and dust. “Our analysis showed that this object is very compact, presumably young, and forming stars at an extremely high rate,” Giuletti said.

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The galaxy has been incredibly elusive for a number of reasons. It is very distant. It is compact. There is a lot of interstellar dust that obscures our view. This is one of the reasons why the James Webb Space Telescope is such a big deal. Its infrared eyes allow it to see through thick veils of dust and see vastly distant regions of our universe. JWST has not yet studied the unseen galaxy, though “in the future, the James Webb Space Telescope will reveal much more about this galaxy, something only it can do at this time,” Giulietti said. In 2019, ALMA released the details of another distant, invisible galaxy — one that turned out to be a “massive monster”. Brilliant light on tricky celestial objects like these helps scientists better understand galaxy formation and evolution. Astronomers are opening these windows into the early universe, and they’ll open even wider as JWST gets to work breaking up all that interstellar dust.