intergalactic gas / Dilute halo gas / metal-line emission / average gas properties / gas particle / halo gas / hotter gas / gas particles / circumgalactic gas / ultra-violet metal-line emission / brightest metal lines / energy range / metal-line emission traces / gas pressure / gas emissivity scales / halo gas mological simulations / neutral gas / cold gas / diffuse halo gas / energy resolution / dense halo gas / expected metal-line surface brightness / metal lines / diffuse gas / gas cloud / energy / /
6 Soft X-ray and ultra-violet metal-line emission from the gas around galaxies The gas around galaxies is diffuse and much fainter than the galaxies themselves. A large fraction of the gas has temperatures between 104.5