Syllabus

Occurrence and state of cosmic diffuse matter – ion ized, atomic, molecular gas and dust – heating and cooling, equilibrium phases – probes of diffuse matter (line and continuum radiations at various wavelengths) – Thermal and io nization equilibrium of HII regions – UV shielding in molecular gas – extinction/reddening/p olarization due to dust – dust heating and IR emission – star forming regions - cosmic rays and n on-thermal synchrotron emission – recombination and re-ionization of IGM – Lyman alph a forest, Mg absorption systems – Gunn Peterson effect – Heating of intracluster gas – Sun yaev- Zeldovich effect – excess entropy problem and possible resolution