The 10th Dennis Sciama Memorial Lecture
Professor James Binney
Department of Physics, Merton College and All Souls Visiting Lecturer, University of Oxford
Galaxies and the intergalactic medium
Cosmology tells us that most "ordinary" matter such as we are made of is not in stars or in the interstellar media of galaxies. So it must lie between galaxies. In rich clusters of galaxies it is so dense and so hot that its thermal X-ray emission has long been detected.