{"author":[{"orcid":"0000-0003-2871-127X","first_name":"Jorryt J","full_name":"Matthee, Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720","last_name":"Matthee"},{"last_name":"Sobral","full_name":"Sobral, David","first_name":"David"},{"first_name":"Behnam","full_name":"Darvish, Behnam","last_name":"Darvish"},{"last_name":"Santos","full_name":"Santos, Sérgio","first_name":"Sérgio"},{"last_name":"Mobasher","full_name":"Mobasher, Bahram","first_name":"Bahram"},{"last_name":"Paulino-Afonso","first_name":"Ana","full_name":"Paulino-Afonso, Ana"},{"last_name":"Röttgering","first_name":"Huub","full_name":"Röttgering, Huub"},{"last_name":"Alegre","full_name":"Alegre, Lara","first_name":"Lara"}],"doi":"10.1093/mnras/stx2061","_id":"11572","publication_status":"published","publication":"Monthly Notices of the Royal Astronomical Society","abstract":[{"lang":"eng","text":"We present spectroscopic follow-up of candidate luminous Ly α emitters (LAEs) at z = 5.7–6.6 in the SA22 field with VLT/X-SHOOTER. We confirm two new luminous LAEs at z = 5.676 (SR6) and z = 6.532 (VR7), and also present HST follow-up of both sources. These sources have luminosities LLy α ≈ 3 × 1043 erg s−1, very high rest-frame equivalent widths of EW0 ≳ 200 Å and narrow Ly α lines (200–340 km s−1). VR7 is the most UV-luminous LAE at z > 6.5, with M1500 = −22.5, even brighter in the UV than CR7. Besides Ly α, we do not detect any other rest-frame UV lines in the spectra of SR6 and VR7, and argue that rest-frame UV lines are easier to observe in bright galaxies with low Ly α equivalent widths. We confirm that Ly α line widths increase with Ly α luminosity at z = 5.7, while there are indications that Ly α lines of faint LAEs become broader at z = 6.6, potentially due to reionization. We find a large spread of up to 3 dex in UV luminosity for >L⋆ LAEs, but find that the Ly α luminosity of the brightest LAEs is strongly related to UV luminosity at z = 6.6. Under basic assumptions, we find that several LAEs at z ≈ 6–7 have Ly α escape fractions ≳ 100  per cent, indicating bursty star formation histories, alternative Ly α production mechanisms, or dust attenuating Ly α emission differently than UV emission. Finally, we present a method to compute ξion, the production efficiency of ionizing photons, and find that LAEs at z ≈ 6–7 have high values of log10(ξion/Hz erg−1) ≈ 25.51 ± 0.09 that may alleviate the need for high Lyman-Continuum escape fractions required for reionization."}],"volume":472,"date_updated":"2022-08-19T08:05:37Z","type":"journal_article","extern":"1","publication_identifier":{"issn":["0035-8711"],"eissn":["1365-2966"]},"page":"772-787","status":"public","external_id":{"arxiv":["1706.06591"]},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","oa":1,"article_processing_charge":"No","acknowledgement":"We thank the referee for a constructive report that has improved the quality and clarity of this work. The authors thank Grecco Oyarzún for discussions. JM acknowledges the support of a Huygens PhD fellowship from Leiden University. DS acknowledges financial support from the Netherlands Organisation for Scientific research (NWO) through a Veni fellowship and from Lancaster University through an Early Career Internal Grant A100679. BD acknowledges financial support from NASA through the Astrophysics Data Analysis Program (ADAP), grant number NNX12AE20G. We thank Kasper Schmidt for providing measurements. Based on observations with the W.M. Keck Observatory through programme C267D. The W.M. Keck Observatory is operated as a scientific partnership amongst the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 097.A-0943, 294.A 5018 and 098.A-0819 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. The authors acknowledge the award of observing time (W16AN004) and of service time (SW2014b20) on the William Herschel Telescope (WHT). WHT and its service programme are operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Based on observations made with the NASA/ESA HST, obtained (from the Data Archive) at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programme #14699. We are grateful for the excellent data sets from the COSMOS, UltraVISTA, SXDS, UDS and CFHTLS survey teams; without these legacy surveys, this research would have been impossible. We have benefited from the public available programming language PYTHON, including the NUMPY, MATPLOTLIB, PYFITS, SCIPY and ASTROPY packages, the astronomical imaging tools SEXTRACTOR, SWARP and SCAMP and the TOPCAT analysis tool (Taylor 2013).","citation":{"apa":"Matthee, J. J., Sobral, D., Darvish, B., Santos, S., Mobasher, B., Paulino-Afonso, A., … Alegre, L. (2017). Spectroscopic properties of luminous Ly α emitters at z ≈ 6–7 and comparison to the Lyman-break population. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href=\"https://doi.org/10.1093/mnras/stx2061\">https://doi.org/10.1093/mnras/stx2061</a>","ista":"Matthee JJ, Sobral D, Darvish B, Santos S, Mobasher B, Paulino-Afonso A, Röttgering H, Alegre L. 2017. Spectroscopic properties of luminous Ly α emitters at z ≈ 6–7 and comparison to the Lyman-break population. Monthly Notices of the Royal Astronomical Society. 472(1), 772–787.","chicago":"Matthee, Jorryt J, David Sobral, Behnam Darvish, Sérgio Santos, Bahram Mobasher, Ana Paulino-Afonso, Huub Röttgering, and Lara Alegre. “Spectroscopic Properties of Luminous Ly α Emitters at z ≈ 6–7 and Comparison to the Lyman-Break Population.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2017. <a href=\"https://doi.org/10.1093/mnras/stx2061\">https://doi.org/10.1093/mnras/stx2061</a>.","ieee":"J. J. Matthee <i>et al.</i>, “Spectroscopic properties of luminous Ly α emitters at z ≈ 6–7 and comparison to the Lyman-break population,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 472, no. 1. Oxford University Press, pp. 772–787, 2017.","mla":"Matthee, Jorryt J., et al. “Spectroscopic Properties of Luminous Ly α Emitters at z ≈ 6–7 and Comparison to the Lyman-Break Population.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 472, no. 1, Oxford University Press, 2017, pp. 772–87, doi:<a href=\"https://doi.org/10.1093/mnras/stx2061\">10.1093/mnras/stx2061</a>.","ama":"Matthee JJ, Sobral D, Darvish B, et al. Spectroscopic properties of luminous Ly α emitters at z ≈ 6–7 and comparison to the Lyman-break population. <i>Monthly Notices of the Royal Astronomical Society</i>. 2017;472(1):772-787. doi:<a href=\"https://doi.org/10.1093/mnras/stx2061\">10.1093/mnras/stx2061</a>","short":"J.J. Matthee, D. Sobral, B. Darvish, S. Santos, B. Mobasher, A. Paulino-Afonso, H. Röttgering, L. Alegre, Monthly Notices of the Royal Astronomical Society 472 (2017) 772–787."},"date_created":"2022-07-13T09:47:39Z","month":"11","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1706.06591"}],"title":"Spectroscopic properties of luminous Ly α emitters at z ≈ 6–7 and comparison to the Lyman-break population","scopus_import":"1","quality_controlled":"1","issue":"1","oa_version":"Preprint","intvolume":"       472","language":[{"iso":"eng"}],"article_type":"original","year":"2017","publisher":"Oxford University Press","day":"01","date_published":"2017-11-01T00:00:00Z","keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: evolution – galaxies: high-redshift","dark ages","reionization","first stars","cosmology: observations"]}