116 research outputs found
Star Formation History since z = 1.5 as Inferred from Rest-Frame Ultaviolet Luminosity Density Evolution
We investigate the evolution of the universal rest-frame ultraviolet
luminosity density from z = 1.5 to the present. We analyze an extensive sample
of multicolor data (U', B, V = 24.5) plus spectroscopic redshifts from the
Hawaii Survey Fields and the Hubble Deep Field. Our multicolor data allow us to
select our sample in the rest-frame ultraviolet (2500 angstrom) over the entire
redshift range to z = 1.5. We conclude that the evolution in the luminosity
density is a function of the form (1+z)^{1.7\pm1.0} for a flat lambda cosmology
and (1+z)^{2.4\pm1.0} for an Einstein-de Sitter cosmology.Comment: 12 pages, 7 figs, 5 tables, submitted to A
Evidence for a Gradual Decline in the Universal Rest-Frame UV Luminosity Density for z < 1
We have utilized various magnitude-limited samples drawn from an extremely
deep and highly complete spectroscopic redshift survey of galaxies observed in
seven colors in the Hawaii Survey Fields and the Hubble Deep Field to
investigate the evolution of the universal rest-frame ultraviolet luminosity
density from z = 1 to the present. The multi-color data (U', B, V, R, I, J,
HK') enable the sample selection to be made in the rest-frame ultraviolet for
the entire redshift range. Due to the large sample size and depth (U_{AB} =
24.75, B_{AB} = 24.75, I_{AB} = 23.5), we are able to accurately determine the
luminosity density to z = 1. We do not confirm the very steep evolution
reported by Lilly et al. (1996) but instead find a shallower slope,
approximately (1+z)^{1.5} for q0 = 0.5, which would imply that galaxy formation
is continuing smoothly to the present time rather than peaking at z = 1. Much
of the present formation is taking place in smaller galaxies. Detailed
comparisons with other recent determinations of the evolution are presented.Comment: 37 pages including 18 figures. Also available at
http://www.ifa.hawaii.edu/~acowie/uvlum.html To be published in the August,
1999 Astronomical Journal (accepted April 22, 1999
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