A Meta-analysis of Cosmic Star-formation History

A meta-analysis is performed of the literature on evolution in cosmic star-formation rate density from redshift unity to the present day. The measurements are extremely diverse, including radio, infrared, and ultraviolet broad-band photometric indicators, and visible and near-ultraviolet line-emission indicators. Although there is large scatter among indicators at any given redshift, virtually all studies find a significant decrease from redshift unity to the present day. This is the most heterogeneously confirmed result in the study of galaxy evolution. When comoving star-formation rate density is treated as being proportional to (1+ z), the meta-analysis gives a best-fit exponent and conservative confidence interval of β = 3.1± 0.7 in a world model with (ΩM ,ΩΛ) = (0.3, 0.7) and β = 3.8± 0.8 in (ΩM ,ΩΛ) = (1.0, 0.0). In either case these evolutionary trends are strong enough that the bulk of the stellar mass at the present day ought to be in old (> 6 Gyr) populations. Subject headings: cosmology: observations — galaxies: evolution — galaxies: stellar content — history and philosophy of astronomy — methods: statistical — stars: formation