Astronomers Accidentally Discovered Hidden Galaxies At the Edge of Time

A team of astronomers has unexpectedly discovered two galaxies that were previously hidden from view at the edge of space and time.

Yoshinobu Fudamoto, an astronomer from Waseda University's Research Institute for Science and Engineering and the National Astronomical Observatory of Japan (NAOJ), directed the team that made the discovery using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. ALMA is an astronomy interferometer comprised of 66 radio telescopes capable of seeing through dust and at extremely long distances.

Rebels-12 and Rebels-29 have been identified in near-infrared radiation, however, Rebels-12-2 and Rebels-29-2 have not been found, implying that these galaxies are severely shrouded in dust. Image credits: alma (eso/naoj/nrao), nasa/esa Hubble Space Telescope, eso, fudamoto et al.

The two new galaxies were discovered while watching two target galaxies known as REBELS-12 and REBELS-29. Bright emissions were detected hundreds of light-years away from the target galaxies. This finding encouraged the researchers to perform more investigations, leading to the discovery of two galaxies known as REBELS-12-2 and REBELS-29-2. These galaxies are obscured by a cloud of cosmic dust and are not visible in ultraviolet or optical light.

According to research published in Nature, the "serendipitous discovery of these two dusty galaxies" at the edge of the universe "shows that our current (UV-based) census of very early galaxies is still incomplete."

The remarkable discovery implies that up to one in every five galaxies during cosmic dawn may be concealed under clouds of cosmic dust, which has ramifications for models of star and galaxy formation during this bygone epoch. In the study, Fudamoto and his colleagues recommend that "a blind, wide-area survey for such sources is required in the future."

“These surveys must observe substantially deeper than had been envisioned previously to sample the fainter dust-obscured, but otherwise ‘normal’ galaxies such as REBELS-12-2 and REBELS-29-2,” the team concluded.

Researchers believe the newly found galaxies developed barely 800 million years after the Universe's beginning, which occurred 13.8 billion years ago.