New instruments on telescopes are allowing us to look back in time at the early universe, when it was only a few billion years old, including spectacular rings of light that represent halos around galaxies.
Far from the center of each galaxy is an abundance of neutral hydrogen. This is where gas is exchanged between the galaxy and its surrounding space. This gas region glows and creates a halo; it also tells a story of how galaxies form and evolve.
The MUSE instrument on the European Southern Observatory’s Very Large Telescope has identified halos around distant galaxies. Previously, images of these glowing rings lacked detail, but astronomers were able to use a gravitational lensing effect of galaxy clusters to see detail and structure.
Gravitational lensing occurs as an effect of Albert Einstein’s theory of general relativity: mass bends light. So the gravitational fields of galaxy clusters bend light, acting like a magnifier of the galaxies behind them.
The best observations of the halos by MUSE were released Monday, presented by Adélaïde Claeyssens during the annual meeting of the European Astronomical Society in Lyon, France. Claeyssens is a Ph.D. student at the Centre de Recherche Astrophysique de Lyon.
“Indeed, massive clusters have the property to bend light rays passing through their center, as predicted by Einstein. This produces the effect of a magnifying glass: the images of background galaxies are magnified,” Claeyssens said in a statement.
In one of the images, the halo appears as a ring of light that is nearly complete.
Seeing the halos in such detail allows scientists to study how the gas varies and the processes unfolding within the halo, which could control the way gas moves across the galaxy.
As astronomers acquire more detailed views of these distant galaxies, they can piece together a portrait of the early universe and learn what it was like as galaxies were forming during the first few billion years.