# Temperature between Galactic Structures

by JamesBrown
Tags: galactic, structures, temperature
 P: 112 Hawking radiation (unruh radiation) is not responsible for heating in the ISM/IGM. Yes, the space between galaxies is generally very hot, $$10^6$$K degrees or so actually. We call that material the intergalactic medium (IGM). The interstellar medium (ISM) is also pretty hot in general. Well, the temperature varies quite a bit, from a few K in cold molecular clouds to $$10^4$$K in H II regions. Generally its a few $$10^3$$K. The heating and cooling processes in the IGM/ISM are complex but its thought that supernovae are generally responsible for heating the gas in the IGM.