Invited review given at the JENAM 2002 in Porto, Workshop ISM, eds. M.A. de Avillez & D. Breitschwerdt, Kluwer.
astro-ph/0212434.

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Abstract. A hot phase of the interstellar medium has now been detected and studied in several objects through its X-ray emission. A proper assessment of its characteristics is relevant for our understanding of several aspects of galaxy properties, from the large scale distribution of matter to the stellar and galaxian evolution, to the dynamics of systems and to the feeding of a central black hole. I will briefly summarize our current understanding of some of the main issues related to the hot gaseous component in galaxies that are fast evolving given the ever more striking and interesting details provided by the X-ray satellites currently operating. I hope to convince you that the X-ray characteristics of the hot gas are quite complex, both in morphology and spectra, in a wide range of objects, which should promote greater efforts in understanding the role played by this component in all galaxies.

Key words: ISM, galaxies

Table of Contents

WHY IS HOT GAS IMPORTANT?

WHERE IS THE HOT GAS?

CHARACTERISTICS OF THE ISM IN STARBURST GALAXIES/REGIONS

EARLY TYPE GALAXIES AND GROUPS

NGC 5846

NGC 1553

NGC 4636

UNEXPECTED PHENOMENA

IC 1262

WHAT CAN WE CONCLUDE FROM ALL OF THIS?

REFERENCES