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We present a catalog of 59 z=4. 5 Lyman alpha emitting galaxies spectroscopically confirmed in a campaign of Keck/DEIMOS follow-up observations to candidates selected in the Large Area Lyman Alpha (LALA) narrow-band imaging survey. We targeted 97 candidates for spectroscopic follow-up; by accounting for the variety of conditions under which we performed spectroscopy, we estimate a selection reliability of about 76%. Together with our previous sample of Keck/LRIS confirmations, the 59 sources confirmed herein bring the total catalog to 73 spectroscopically confirmed z=4. 5 Lyman alpha emitting galaxies in the 0. 7 square degrees covered by the LALA imaging. As with the Keck/LRIS sample, we find that a non-negligible fraction of the confirmed Lyman alpha lines have rest-frame equivalent widths (wₑ₄ₒₓ) which exceed the maximum predicted for normal stellar populations: 17% -- 31% (93% confidence) of the detected galaxies show wₑ₄ₒₓ > 190 AA, and 12% -- 27% (90% confidence) show wₑ₄ₒₓ > 240 AA. We construct a luminosity function of z=4. 5 Lyman alpha emission lines for comparison to Lyman alpha luminosity functions spanning 3. 1 < z < 6. 6. We find no significant evidence for Lyman alpha luminosity function evolution from z ~ 3 to z ~ 6. This result supports the conclusion that the intergalactic medium remains largely reionized from the local universe out to z=6. 5. It is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z~3 and z~6 in continuum-selected Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations.
Dawson et al. (Thu,) studied this question.