Dust, Gas, and Stars: Astrophysics of Matter in High-Redshift Galaxies

The star-formation activity of the young universe is dominated by galaxies that undergo a dust-enshrouded star-bursting phase where 100 to 1000 stars are born in a year over 100 million year time scales. Theories of galaxy formation and evolution are still incapable of explaining such rapid star-forming activity. Extragalactic and cosmological surveys with the Herschel Space Observatory have now allowed the detection of many hundred thousand starburst galaxies that were previously unknown in the optical wavelengths due to high dust extinction and statistical studies are now underway to characterize the astrophysical properties of these dusty galaxies. I will present results from such studies on the dust, gas, and stellar content of young galaxies in the distant universe. The extragalactic surveys have also revealed that one in 500 distant Herschel galaxies is also “gravitationally lensed” by an intervening galaxy in the foreground. Statistical properties of such lensed Herschel galaxies will also be presented.