What a newly discovered gas bridge between galaxies tells us about the cosmic cycle of matter
Most of the ordinary matter in the universe is hydrogen. But surprisingly, less than 20% of this hydrogen sits inside galaxies. The rest lies in the vast spaces between them – the so-called intergalactic medium.
This cosmic reservoir is thought to fuel the birth of new stars, as gas slowly falls into galaxies over billions of years. Yet much of that material doesn’t stay put: supernova explosions and powerful outflows from supermassive black holes can fling gas back out into intergalactic space.
The push-and-pull between inflows and outflows is central to understanding how galaxies grow and change over cosmic time. Probing this balance is one of the aims of the WALLABY survey, carried out using the Australian SKA Pathfinder (ASKAP) telescope at Inyarrimanha Ilgari Bundara, CSIRO’s Murchison Radio-astronomy Observatory in Western Australia.
A new discovery from WALLABY, published today in Monthly Notices of the Royal Astronomical Society, sheds new light on the cosmic cycle of matter into, through and out of galaxies.