SIT Spectra of Faint Field Galaxies

Extract

Digital SIT spectra have been obtained in collaboration with J.E. Gunn and W.L.W. Sargent for a sample of 49 field galaxies chosen from Kron's survey of selected area 68. Most have apparent visual magnitudes in the range 19 to 21. Redshifts have been measured for 48 of the 49 galaxies. The redshift (or, equivalently, luminosity) distribution for the sample is anomalous in that ≥ 10% of the sample has z ≥ 0.3 (and, thus, L ≥ 6 L^*). These high z and L galaxies are among the bluest objects in the sample. These data require substantial evolution of at least some galaxies at small z. It is tempting to speculate that this luminous, blue field galaxy population is related to the Butcher and Oemler blue cluster galaxies found in the same redshift range.