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Session 103 - Galaxy Evolution.
Display session, Thursday, January 16
We have computed the luminosity function (LF) for a sample of 1236 field galaxies at intermediate redshifts 0.12 < z < 0.6, gathered from two Canadian Network for Observational Cosmology (CNOC) redshift surveys. The data set combines field galaxies from the completed CNOC1 cluster redshift survey with a preliminary sample from the ongoing CNOC2 field galaxy redshift survey. We find Schechter parameters M_B_AB - 5 \log h = -19.65 \pm 0.1 and \alpha = -0.95 \pm 0.1 in the B_AB-band. Comparisons of the CNOC results to other intermediate-redshift LF's from the Canada-France (CFRS) and Autofib redshift surveys show only broad agreement among these independent samples, and there are specific differences which may require larger samples and/or investigation of potential systematic effects to resolve.
We also find distinctly different LF's for red and blue galaxies: red galaxies have a shallow faint-end slope \alpha = -0.5, while blue galaxies have a steep \alpha = -1.5. Moreover, the red LF changes little with redshift, while the blue luminosity density has increased significantly at higher z. These trends are qualitatively consistent with those first seen in the CFRS, though the onset of the blue galaxy evolution occurs at lower z in the larger CNOC sample. Comparison of the r-band CNOC LF to the local z \sim 0.1 result from the Las Campanas redshift survey (LCRS) suggests that luminosity-dependent evolution, increasing at the faint end, is needed to match the CNOC and LCRS LF's, if galaxy evolution is the sole cause of the differences seen. However, an important caveat throughout is that the specific details of the construction of different surveys may complicate the comparison of LF results and so may need to be considered carefully.
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