"Intergalactic gas" refers to the gas that exists between galaxies in outer space. It's made up of various elements and can include hydrogen, helium, and other atoms. Full definition
Hubble's spectrographs — partially fulfilling the promise of a large space telescope envisioned by Spitzer all those years ago — were critical in allowing astronomers to map the web - like structure of intergalactic gas in the universe, now termed the «cosmic web.» (hubble25th.org)
But astronomers were not finding the same quantity of 10,000 - degree intergalactic gas in the local universe. (hubble25th.org)
Cannan Huey - You, just 11 years old, impressed professional astronomers in January with his research on a massive intergalactic gas cloud. (greenbankobservatory.org)