Surprise! Cold Gas 'Halos' Found Around Brightest Objects in Universe

VLT Sees Halos Around Quasars
A mosaic of 18 of the 19 quasars observed using the European Southern Observatory's Very Large Telescope. The survey revealed that all 19 quasars had bright halos. (Image credit: ESO/Borisova et al.)

Gas halos around distant galaxies are colder and more common than previously believed, a new study suggests. The finding could force astronomers to rethink some of their theories about galaxy formation.

Researchers examined 19 quasars, or galaxies with very active supermassive black holes at their centers, using the European Southern Observatory's Very Large Telescope (VLT) in Chile. You can see a video of the quasar halos here. Quasar black holes eat huge amounts of nearby material, such as gas and stars, very quickly, causing the galaxy centers to blast out large amounts of radiation. This makes quasars the most luminous objects in the universe.

Previous studies had found that about 10 percent of all quasars have halos, which are made of gas from the intergalactic medium and extend up to 300,000 light-years from the quasars' cores. So the astronomers were surprised to find halos around all 19 of their study objects. [Distant Quasar Lights Up Galactic Halo (Video)]

"It is still too early to say if this is due to our new observational technique or if there is something peculiar about the quasars in our sample," study lead author Elena Borisova, an astrophysics professor at ETH Zurich in Switzerland, said in a statement, referring to the group's use of a relatively new instrument on the VLT called MUSE (Multi-Unit Spectroscopic Explorer).


"So there is still a lot to learn; we are just at the beginning of a new era of discoveries," Borisova added.

The survey held another surprise as well: The newly studied halos have temperatures of around 18,000 degrees Fahrenheit (10,000 degrees Celsius).

"This revelation is in strong disagreement with currently accepted models of the structure and formation of galaxies, which suggest that gas in such close proximity to galaxies should have temperatures upwards of a million degrees [Celsius; 1.8 million degrees F]," European Southern Observatory representatives said in the same statement.

A paper based on the research will appear in the Astrophysical Journal.

Follow Elizabeth Howell @howellspace, or @Spacedotcom. We're also on Facebookand Google+. Original article on

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at:

Elizabeth Howell
Staff Writer, Spaceflight

Elizabeth Howell (she/her), Ph.D., is a staff writer in the spaceflight channel since 2022 covering diversity, education and gaming as well. She was contributing writer for for 10 years before joining full-time. Elizabeth's reporting includes multiple exclusives with the White House and Office of the Vice-President of the United States, an exclusive conversation with aspiring space tourist (and NSYNC bassist) Lance Bass, speaking several times with the International Space Station, witnessing five human spaceflight launches on two continents, flying parabolic, working inside a spacesuit, and participating in a simulated Mars mission. Her latest book, "Why Am I Taller?", is co-written with astronaut Dave Williams. Elizabeth holds a Ph.D. and M.Sc. in Space Studies from the University of North Dakota, a Bachelor of Journalism from Canada's Carleton University and a Bachelor of History from Canada's Athabasca University. Elizabeth is also a post-secondary instructor in communications and science at several institutions since 2015; her experience includes developing and teaching an astronomy course at Canada's Algonquin College (with Indigenous content as well) to more than 1,000 students since 2020. Elizabeth first got interested in space after watching the movie Apollo 13 in 1996, and still wants to be an astronaut someday. Mastodon: