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Abstract: We present a catalog of 59 z=4.5 Lyman alpha emitting galaxiesspectroscopically confirmed in a campaign of Keck-DEIMOS follow-up observationsto candidates selected in the Large Area Lyman Alpha LALA narrow-band imagingsurvey. We targeted 97 candidates for spectroscopic follow-up; by accountingfor the variety of conditions under which we performed spectroscopy, weestimate a selection reliability of about 76%. Together with our previoussample of Keck-LRIS confirmations, the 59 sources confirmed herein bring thetotal catalog to 73 spectroscopically confirmed z=4.5 Lyman alpha emittinggalaxies in the 0.7 square degrees covered by the LALA imaging. As with theKeck-LRIS sample, we find that a non-negligible fraction of the confirmed Lymanalpha lines have rest-frame equivalent widths w {rest} which exceed themaximum predicted for normal stellar populations: 17% - 31% 93% confidenceof the detected galaxies show w {rest} > 190 AA, and 12% - 27% 90%confidence show w {rest} > 240 AA. We construct a luminosity function of z=4.5Lyman alpha emission lines for comparison to Lyman alpha luminosity functionsspanning 3.1 < z < 6.6. We find no significant evidence for Lyman alphaluminosity function evolution from z ~ 3 to z ~ 6. This result supports theconclusion that the intergalactic medium remains largely reionized from thelocal universe out to z=6.5. It is somewhat at odds with the pronounced drop inthe cosmic star formation rate density recently measured between z~3 and z~6 incontinuum-selected Lyman-break galaxies, and therefore potentially sheds lighton the relationship between the two populations.



Autor: Steve Dawson, James E. Rhoads, Sangeeta Malhotra, Daniel Stern, JunXian Wang, Arjun Dey, Hyron Spinrad, Buell T. Jannuzi

Fuente: https://arxiv.org/







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