Astronomers said last week (February 16, 2022) they’ve found the largest galaxy yet seen, not in visible light, but via radio astronomy. This galaxy spans a mind-boggling 16 million light-years.
Some 100 Milky Way galaxies laid end to end would about equal the length of this newly discovered galaxy. Scientists have named the new galaxy Alcyoneus, for the giant of Greek myth. They said it’s so large that it might provide insights about the the cosmic web – the observed network of filaments and clusters, made of galaxies, plus the great voids between them – that astronomers observe all around us in the modern universe.
Alcyoneus lies relatively nearby as galaxies go, only 3 billion light-years away. It spans an area in our sky the size of the full moon.
Martijn Oei of Leiden University led the research team. Their work was to reprocess existing images from the Low Frequency Array (LOFAR) telescope to tease the giant out of the darkness. You can read a pre-print of their paper on arXiv dated February 11, 2022. The paper is accepted for publication in the journal Astronomy and Astrophysics.