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Abstract Recent evidence suggests that high-redshift Ly α emitting galaxies (LAEs) with log L ( Ly α ) > 43.5 erg s − 1 , referred to as ultraluminous LAEs (ULLAEs), may show less evolution than lower-luminosity LAEs in the redshift range z = 5.7–6.6. Here we explore the redshift evolution of the velocity widths of the Ly α emission lines in LAEs over this redshift interval. We use new wide-field, narrowband observations from Subaru/Hyper Suprime-Cam to provide a sample of 24 z = 6.6 and 12 z = 5.7 LAEs with log L ( Ly α ) > 43 erg s − 1 , all of which have follow-up spectroscopy from Keck/DEIMOS. Combining with archival lower-luminosity data, we find a significant narrowing of the Ly α lines in LAEs at log L ( Ly α ) < 43.25 erg s − 1 —somewhat lower than the usual ULLAE definition—at z = 6.6 relative to those at z = 5.7, but we do not see this in higher-luminosity LAEs. As we move to higher redshifts, the increasing neutrality of the intergalactic medium should increase the scattering of the Ly α lines, making them narrower. The absence of this effect in the higher-luminosity LAEs suggests they may lie in more highly ionized regions, self-shielding from the scattering effects of the intergalactic medium.
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The Web Epoch of Reionization Lyα Survey (WERLS). I. MOSFIRE Spectroscopy of z ∼ 7–8 Lyα Emitters*
Abstract We present the first results from the Web Epoch of Reionization LyαSurvey (WERLS), a spectroscopic survey of Lyαemission using Keck I/MOSFIRE and LRIS. WERLS targets bright (J< 26) galaxy candidates with photometric redshifts of 5.5 ≲z≲ 8 selected from pre-JWST imaging embedded in the Epoch of Reionization (EoR) within three JWST deep fields: CEERS, PRIMER, and COSMOS-Web. Here, we report 11z∼ 7–8 Lyαemitters (LAEs; three secure and eight tentative candidates) detected in the first five nights of WERLS MOSFIRE data. We estimate our observed LAE yield is ∼13%, which is broadly consistent with expectations assuming some loss from redshift uncertainty, contamination from sky OH lines, and that the Universe is approximately half-ionized at this epoch, whereby observable Lyαemission is unlikely for galaxies embedded in a neutral intergalactic medium. Our targets are selected to be UV-bright, and span a range of absolute UV magnitudes with −23.1 <MUV< −19.8. With two LAEs detected atz= 7.68, we also consider the possibility of an ionized bubble at this redshift. Future synergistic Keck+JWST efforts will provide a powerful tool for pinpointing beacons of reionization and mapping the large-scale distribution of mass relative to the ionization state of the Universe.
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- Award ID(s):
- 2009577
- PAR ID:
- 10524302
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 970
- Issue:
- 1
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 50
- Size(s):
- Article No. 50
- Sponsoring Org:
- National Science Foundation
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