Lyalpha-EMITTING GALAXIES AT REDSHIFT zapprox 4.5 IN THE LALA CETUS FIELD
- Center for Astrophysics, University of Science and Technology of China, Hefei, Anhui 230026 (China)
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)
- National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, 100012 Beijing (China)
We present a large sample of Lyalpha-emitting galaxies (LAEs) spectroscopically confirmed at redshift z approx 4.5, based on Inamori-Magellan Areal Camera and Spectrograph spectroscopic observations of candidate zapprox 4.5 Lyalpha-emitting galaxies in the large area Lyman alpha (LALA) narrowband imaging survey Cetus field. We identify 110 of them as z approx 4.5 Lyalpha emitters based on single-line detections with no continuum emission blueward of the line. Six foreground galaxies are identified, either based on multiple lines or blueward continuum emission. The Lyalpha confirmation rate varies from <50% to 76% for candidates selected in different narrowband filters at slightly different redshifts. We find a drop in the LAE density at redshift 4.50 +- 0.03 from redshift 4.39 to 4.47 by a factor of 66%, which could be a large-scale void in the distribution of star-forming galaxies (approx18 Mpc along the line of sight and approx80 Mpc across). The sample includes many objects with equivalent widths (EWs) approx>200 A. These large EW candidates are spectroscopically confirmed at the same rate as candidates with more modest EWs. A composite spectrum of all 110 confirmed LAEs shows the characteristic asymmetry of the Lyalpha line. It also places new and stringent upper limits on the C IV 1549 A/Lyalpha and He II 1640 A/Lyalpha line ratios, providing a new upper limit on the fraction of active galactic nuclei in Lyalpha selected galaxy samples, and on the contribution of Pop III populations. Finally, we calculate the Lyalpha luminosity function for our z approx 4.5 sample, which is consistent with those at other redshifts, showing that there is no evolution in Lyalpha luminosity function from z = 3.1 to 6.6.
- OSTI ID:
- 21378139
- Journal Information:
- Astrophysical Journal, Vol. 706, Issue 1; Other Information: DOI: 10.1088/0004-637X/706/1/762; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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