The Star-formation History of the Universe.pdf

a r X i v : a s t r o - p h / 9 9 0 6 3 0 8 v 1 1 8 J u n 1 9 9 9 THE STAR-FORMATION HISTORY OF THE UNIVERSE MICHAEL ROWAN-ROBINSON Astrophysics Group, Blackett Laboratory, Imperial College of Science Technology and Medicine Prince Consort Road, London SW7 2BZ 1. Introduction Many authors have attempted to model the star formation history of the universe (eg Cole et al 1994, Pei and Fall 1995) or equivalently the evolution of the starburst galaxy population (eg Franceschini et al 1991, 1994, 1997, Blain and Longair 1993, Pearson and Rowan-Robinson 1996, Guiderdoni et al 1998, Dwek et al 1998, Blain et al 1999). Most of these studies explore a small range of models designed to fit the available observations. In the present paper I report the results of a parameterized approach to the star formation history of the universe, which allows a large category of possi- ble histories to be explored and quantified. The parametrized models can be compared with a wide range of source-count and background data at far infrared and submillimetre wavelengths to narrow down the parameter space that the star formation history can occupy. Throughout this paper I use the most recent Bruzual and Charlot star formation scenarios, with a Salpeter IMF with mass cutoffs at 0.1 and 100 M⊙, for which the relevant conversion factors are: L(Hα)/L⊙ = 107.60φ??, (1) L(60μm)/L⊙ = 109.66?φ??, (2) L(2800A?)/L⊙ = 109.35φ??, (3) L(2000A?)/L⊙ = 109.50φ??, (4) φ?? = 42φ?Z , (5) where φ??, φ?Z , are the star and metal formation rates in solar masses per year per cubic Mpc and ? is the fraction of opt-uv light absorbed by dust (Rowan-Robinson et al 1997). A Hubble constant of 50 km/s/Mpc is used throughout, and ?o = 1 (unless otherwise stated). 2 MICHAEL ROWAN-ROBINSON 2. Star formation rate derived from ultraviolet data I first estimate the star formation history at uv wavelengths, with no cor- rection for the effects of dust. For the local, z = 0, star formation rate, I have gone back to the Hα dat