Status Report

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

By SpaceRef Editor
January 1, 2003
Filed under , ,

Astrophysics, abstract

From: Karl Glazebrook <[email protected]>
Date: Wed, 1 Jan 2003 00:18:04 GMT (192kb)

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

Comments: 17 pages, 11 figures, ApJ in press (April 10th 2003)

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 $propto
(1+z)^eta$ out to z=1, then we find that $eta$ 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 AA$^{-1}$
Mpc$^{-3}$) at 2–5AA resolution 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$alpha$ 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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