The Chandra X-ray observatory has found a large halo of gas surrounding the Milky Way and the Magellanic cloud galaxies – and it could be part of the solution to the missing baryon problem.
In the observable early universe there’s a relatively large amount of baryonic matter – eg, the garden variety stuff made up of protons and neutrons – in what would otherwise be a soup of exotic particles. The baryonic matter observable around 10 billion years in the past accounts for around a sixth of the mass of existing unobservable – AKA “Dark” – matter.
In the modern universe, approximately half of that sixth has gone “missing”.
The discovery of this gas cloud goes a fair way to explaining where some of that missing baryonic matter has gone, since large hot gas haloes around galaxies are apparently standard issue. The one surrounding the LMC, SMC and Milky Way has an approximated mass of between 10 and 60 billion suns.
As time goes on I expect that both more accurate measurements and more discoveries of these clouds around other galaxies will take place as the technology to detect these large-mass-but-low-density clouds improves.
Images courtesy of NASA.
Article summarised from NASA – Chandra Observatory Releases available here: