On the supernovae heating of intergalactic medium
  We present estimates of the energy input from supernovae (SNe) into the intergalactic medium using (i) recent measurements of Si and Fe abundances in the intracluster medium (ICM) and (ii) self-consistent gasdynamical galaxy formation simulations that include processes of cooling, star formation, SNe feedback, and a multi-phase model of the interstellar medium. We estimate the energy input from observed abundances using two different assumptions: (i) spatial uniformity of metal abundances in the ICM and (ii) radial abundance gradients. We show that these two cases lead to energy input estimates which are different by an order of magnitude, highlighting a need for observational data on large-scale abundance gradients in clusters. Analysis of galaxy formation results and estimates from observed Fe and Si abundances indicates that the SNe energy input can be important for heating of the entire ICM (providing energy of ~1 keV per particle) only if the ICM abundances are uniform and the efficiency of gas heating by SN explosions is close to 100% (implying that all of the initial kinetic energy of the explosion goes into heating of the ICM). We conclude that unless these most favorable conditions are met, SNe alone are unlikely to provide sufficient energy input to heat all of the cluster ICM and may need to be supplemented or even substituted by some other heating process(es). (Abridged) 
Andrey V. Kravtsov (Ohio State), Gustavo Yepes (Universidad Aut\'onoma   de Madrid)