Interstellar Medium in Extremely High Star Formation Regions: A Prospect of Observations on the “Millimetron” Space Observatory

High star-formation rate and emission from the active galactic nucleus can significantly transform the interstellar medium. In ultraluminous infrared galaxies, in which the star-formation rate reaches thousands of solar masses per year, the gas and dust are considerably affected by the ionizing radiation, cosmic rays and shockwaves, that can be about a factor of 100–1000 larger than typical values in quiet star-forming galaxies. In these conditions, the emissivity of the gas and dust changes: in dense gas, high ionic and molecular transitions get excited, while dust grains are heated to high temperatures. In this work, we analyse the possibilities for studying the interstellar medium in extreme conditions of ultra-luminous infrared galaxies at redshifts 0–3, utilising the atomic and molecular lines, and dust continuum in far infrared range 100–500μ m. We discuss the prospect of observations using the instruments of the Millimetron Space Observatory.