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The Sloan Digital Sky Survey: The Cosmic Spectrum and Star-Formation History

Karl Glazebrook·Ivan K. Baldry·Michael R. Blanton·Jon Brinkmann·Andrew Connolly·Istvan Csabai·Masataka Fukugita·Zeljko Ivezic·Jon Loveday·Avery Meiksin·Robert Nichol·Eric Peng·Donald P. Schneider·Mark SubbaRao·Christy Tremonti·Donald G. York
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Abstract

We present a determination of the `Cosmic Optical Spectrum' of the Universe, i.e. the ensemble emission from galaxies, as determined from the red-selected Sloan Digital Sky Survey main galaxy sample and compare with previous results of the blue-selected 2dF Galaxy Redshift Survey. Broadly we find good agreement in both the spectrum and the derived star-formation histories. If we use a power-law star-formation history model where star-formation rate $\propto (1+z)^β$ out to z=1, then we find that $β$ of 2 to 3 is still the most likely model and there is no evidence for current surveys missing large amounts of star formation at high redshift. In particular `Fossil Cosmology' of the local universe gives measures of star-formation history which are consistent with direct observations at high redshift. Using the photometry of SDSS we are able to derive the cosmic spectrum in absolute units (i.e.$ W Å$^{-1}$ Mpc$^{-3}$) at 2--5Åresolution and find good agreement with published broad-band luminosity densities. For a Salpeter IMF the best fit stellar mass/light ratio is 3.7--7.5 $\Msun/\Lsun$ in the r-band (corresponding to $\omstars h = 0.0025$--0.0055) and from both the stellar emission history and the H$α$ luminosity density independently we find a cosmological star-formation rate of 0.03--0.04 h $\Msun$ yr$^{-1}$ Mpc$^{-3}$ today.

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Karl Glazebrook, Ivan K. Baldry, Michael R. Blanton, Jon Brinkmann, Andrew Connolly, Istvan Csabai, Masataka Fukugita, Zeljko Ivezic, Jon Loveday, Avery Meiksin, Robert Nichol, Eric Peng, Donald P. Schneider, Mark SubbaRao, Christy Tremonti, Donald G. York. 2003-01-01. The Sloan Digital Sky Survey: The Cosmic Spectrum and Star-Formation History. https://doi.org/10.1086/368161

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