Cosmic dust clouds obscure hidden ‘empty space’ galaxies

In a case of celestial serendipity, an international team of researchers has discovered two hidden galaxies in empty space – the area devoid of almost anything at all – beaming out from behind huge clouds of space dust. One of them represents the most distant dust-obscured galaxies known to date.

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A schematic of the results of this research showing two hidden galaxies. Credit: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope

The discovery suggests that our current census of our local universe is still incomplete.

“These new galaxies were missed not because they are extremely rare, but only because they are completely dust-obscured,” explains Yoshinobu Fudamoto from Waseda University and the National Astronomical Observatory of Japan.

The signals were discovered with the Atacama Large Millimeter/submillimeter Array (ALMA), when researchers were attempting to observe different targets.

Read more: The mysteries of ultradiffuse galaxies

Beyond their trickster shenanigans, the galaxies also reveal details about the early universe. Light takes a long time to travel to Earth, so the images snapped show what the galaxies looked like 13 billion years ago. Interestingly, they weren’t all that different to the typical galaxy in the same epoch – they were just playing hide-and-seek behind the cosmic cloud.

The researchers hope they can expand the galaxy census using the James Webb Space Telescope (JWST) along with the ALMA.

“Completing our census of early galaxies with the currently missing, dust-obscured galaxies, like the ones we found this time, will be one of the main objectives of JWST and ALMA surveys in the near future,” says co-author Pascal Oesch from University of Geneva, Switzerland.

Distant galaxies imaged with alma credit alma eso noaj nrao nasa esa hubble space telescope fudamoto et al
Distant galaxies imaged with ALMA, the Hubble Space Telescope, and the European Southern Observatory’s VISTA telescope. Green and orange colors represent radiations from ionized carbon atoms and dust particles, respectively, observed with ALMA, and blue represents near-infrared radiation observed with VISTA and Hubble Space Telescopes. Credit: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, ESO, Fudamoto et al.

The study was published in Nature and included researchers from Swinburne University of Technology and the ARC Centre of Excellence for All Sky Astrophysics in 3D.

Who knows what other galaxies we will find out there, if we have a big enough telescope?

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