Cosmic Star-Formation History

I review some recent progress made in our understanding of galaxy evolution and the cosmic history of star formation. Like bookends, the results obtained from deep ground-based spectroscopy and from the Hubble Deep Field imaging survey put brackets around the intermediate redshift interval, 1 < z < 2, where starbirth probably peaked at a rate 10 times higher than today. The steady decline observed since z ∼ 1 is largely associated with late-type galaxies. At z ∼ 2.5, the Lyman-break selected objects may represent the precursors of present-day spheroids, but appear, on average, quite underluminous relative to the expectations of the standard early-and-rapidly forming picture for spheroidal systems. The observed ultraviolet light density accounts for the bulk of the metals seen today in “normal” massive galaxies.