Intergalactic Medium (IMAGE) University of Washington Caption This is a depiction of hydrogen gas within the intergalactic medium, or IGM, with bright areas indicating high gas density. Credit Vid Iršič Usage Restrictions Must include credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.