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ID:
731798.0,
MPI für Astronomie / Publikationen_mpia |
The Grism Lens-Amplified Survey from Space (GLASS). III. A census of Lyα e mission at z > 7 from HST spectroscopy |
Authors: | Schmidt, K. B.; Treu, T.; Bradač, M.; Vulcani, B.; Huang, K. -. H.; Hoag, A.; Maseda, M.; Guaita, L.; Pentericci, L.; Brammer, G. B.; Dijkstra, M.; Dressler, A.; Fontana, A.; Henry, A. L.; Jones, T. A.; Mason, C.; Trenti, M.; Wang, X. | Date of Publication (YYYY-MM-DD): | 2016 | Title of Journal: | The Astrophysical Journal | Volume: | 818 | Issue / Number: | 1 | Start Page: | id. 38 (22 pp) | Audience: | Not Specified | Abstract / Description: | We present a census of Lyα emission at z≳ 7, utilizing deep near-infrared Hubble Space Telescope grism spectroscopy from the first six completed clusters of the Grism Lens-Amplified Survey from Space (GLASS). In 24/159 photometrically selected galaxies we detect emission lines consistent with Lyα in the GLASS spectra. Based on the distribution of signal-to-noise ratios and on simulations, we expect the completeness and the purity of the sample to be 40%-100% and 60%-90%, respectively. For the objects without detected emission lines we show that the observed (not corrected for lensing magnification) 1σ flux limits reach 5 × 10-18 erg s-1 cm-2 per position angle over the full wavelength range of GLASS (0.8-1.7 μm). Based on the conditional probability of Lyα emission measured from the ground at z˜ 7, we would have expected 12-18 Lyα emitters. This is consistent with the number of detections, within the uncertainties, confirming the drop in Lyα emission with respect to z˜ 6. Deeper follow-up spectroscopy, here exemplified by Keck spectroscopy, is necessary to improve our estimates of completeness and purity and to confirm individual candidates as true Lyα emitters. These candidates include a promising source at z = 8.1. The spatial extent of Lyα in a deep stack of the most convincing Lyα emitters with < z> = 7.2 is consistent with that of the rest-frame UV continuum. Extended Lyα emission, if present, has a surface brightness below our detection limit, consistent with the properties of lower-redshift comparison samples. From the stack we estimate upper limits on rest-frame UV emission line ratios and find {f}{{C}{{IV}}}/{f}{Lyα }≲ 0.32 and {f}{{C}{{III}}]}/{f}{Lyα }≲ 0.23, in good agreement with other values published in the literature. | Free Keywords: | galaxies: high-redshift; methods: data analysis; techniques: spectroscopic | External Publication Status: | published | Document Type: | Article |
Communicated by: | N. N. | Affiliations: | MPI für Astronomie | Identifiers: | ISSN:0004-637X %R 10.3847/0004-637X/818/1/38 URL:http://adsabs.harvard.edu/abs/2016ApJ...818...38S
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