{"quality_controlled":"1","title":"The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: What makes a galaxy a Lyman α emitter?","status":"public","oa_version":"Preprint","oa":1,"date_created":"2022-07-07T09:33:39Z","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publisher":"Oxford University Press","scopus_import":"1","extern":"1","publication_status":"published","date_published":"2021-07-01T00:00:00Z","issue":"1","abstract":[{"text":"We present the first results from the X-SHOOTER Lyman α survey at z = 2 (XLS-z2). XLS-z2 is a deep spectroscopic survey of 35 Lyman α emitters (LAEs) utilizing ≈90 h of exposure time with Very Large Telescope/X-SHOOTER and covers rest-frame Ly α to H α emission with R ≈ 4000. We present the sample selection, the observations, and the data reduction. Systemic redshifts are measured from rest-frame optical lines for 33/35 sources. In the stacked spectrum, our LAEs are characterized by an interstellar medium with little dust, a low metallicity, and a high ionization state. The ionizing sources are young hot stars that power strong emission lines in the optical and high-ionization lines in the ultraviolet (UV). The LAEs exhibit clumpy UV morphologies and have outflowing kinematics with blueshifted Si II absorption, a broad [O III] component, and a red-skewed Ly α line. Typically, 30 per cent of the Ly α photons escape, of which one quarter on the blue side of the systemic velocity. A fraction of Ly α photons escape directly at the systemic suggesting clear channels enabling an ≈10 per cent escape of ionizing photons, consistent with an inference based on Mg II. A combination of a low effective H I column density, a low dust content, and young starburst determines whether a star-forming galaxy is observed as an LAE. The first is possibly related to outflows and/or a fortunate viewing angle, while we find that the latter two in LAEs are typical for their stellar mass of 109 M⊙.","lang":"eng"}],"main_file_link":[{"url":"https://arxiv.org/abs/2102.07779","open_access":"1"}],"type":"journal_article","day":"01","month":"07","article_processing_charge":"No","date_updated":"2022-08-18T10:49:00Z","keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: formation","galaxies: ISM","galaxies: starburst","dark ages","reionization","first stars"],"acknowledgement":"We thank the referee for constructive comments and suggestions. We thank Dawn Erb, Ruari Mackenzie, Ivan Oteo, Ryan Sanders, and Johannes Zabl for useful discussions and suggestions. It is a pleasure to thank the ESO User Support, in particular Giacomo Beccari, Carlo Manara, John Pritchard, Marina Rejkuba, and Lowell Tacconi-Garman for assistance in the preparation and execution of the observations. Based on observations obtained with the VLT, programs 084.A-0303, 088.A-0672, 091.A-0413, 091.A-0546, 092.A0774, 097.A-0153, 098.A-0819, 099.A-0758, 099.A-0254, 101.B0779, and 102.A-0652. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme ID 179.A-2005 and on data products produced by CALET and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. Based on observations made with the NASA/ESA HST through programs 9133, 9367, 11694, and 12471, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA), and the Canadian Astronomy Data Centre (CADC/NRC/CSA). This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. MG was supported by NASA through the NASA Hubble Fellowship grant HST-HF2-51409 and acknowledges support from HST grants\r\nHST-GO-15643.017-A, HST-AR-15039.003-A, and XSEDE grant TG-AST180036. GP acknowledges support from the Netherlands Research School for Astronomy (NOVA). RA acknowledges the support of ANID FONDECYT Regular Grant 1202007. We gratefully acknowledge the PYTHON programming language, its NUMPY, MATPLOTLIB, SCIPY, LMFIT (Jones et al. 2001; Hunter 2007; van der Walt, Colbert & Varoquaux 2011), PANDAS (McKinney 2010), and ASTROPY (Astropy Collaboration 2013) packages, and the TOPCAT analysis tool (Taylor 2013). Dedicated to the memory of A. C. J.Matthee (1953–2020).","intvolume":"       505","volume":505,"year":"2021","citation":{"mla":"Matthee, Jorryt J., et al. “The X-SHOOTER Lyman α Survey at z = 2 (XLS-Z2) I: What Makes a Galaxy a Lyman α Emitter?” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 505, no. 1, Oxford University Press, 2021, pp. 1382–412, doi:<a href=\"https://doi.org/10.1093/mnras/stab1304\">10.1093/mnras/stab1304</a>.","ieee":"J. J. Matthee <i>et al.</i>, “The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: What makes a galaxy a Lyman α emitter?,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 505, no. 1. Oxford University Press, pp. 1382–1412, 2021.","ista":"Matthee JJ, Sobral D, Hayes M, Pezzulli G, Gronke M, Schaerer D, Naidu RP, Röttgering H, Calhau J, Paulino-Afonso A, Santos S, Amorín R. 2021. The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: What makes a galaxy a Lyman α emitter? Monthly Notices of the Royal Astronomical Society. 505(1), 1382–1412.","apa":"Matthee, J. J., Sobral, D., Hayes, M., Pezzulli, G., Gronke, M., Schaerer, D., … Amorín, R. (2021). The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: What makes a galaxy a Lyman α emitter? <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href=\"https://doi.org/10.1093/mnras/stab1304\">https://doi.org/10.1093/mnras/stab1304</a>","chicago":"Matthee, Jorryt J, David Sobral, Matthew Hayes, Gabriele Pezzulli, Max Gronke, Daniel Schaerer, Rohan P Naidu, et al. “The X-SHOOTER Lyman α Survey at z = 2 (XLS-Z2) I: What Makes a Galaxy a Lyman α Emitter?” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2021. <a href=\"https://doi.org/10.1093/mnras/stab1304\">https://doi.org/10.1093/mnras/stab1304</a>.","ama":"Matthee JJ, Sobral D, Hayes M, et al. The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: What makes a galaxy a Lyman α emitter? <i>Monthly Notices of the Royal Astronomical Society</i>. 2021;505(1):1382-1412. doi:<a href=\"https://doi.org/10.1093/mnras/stab1304\">10.1093/mnras/stab1304</a>","short":"J.J. Matthee, D. Sobral, M. Hayes, G. Pezzulli, M. Gronke, D. Schaerer, R.P. Naidu, H. Röttgering, J. Calhau, A. Paulino-Afonso, S. Santos, R. Amorín, Monthly Notices of the Royal Astronomical Society 505 (2021) 1382–1412."},"article_type":"original","_id":"11523","language":[{"iso":"eng"}],"publication":"Monthly Notices of the Royal Astronomical Society","author":[{"orcid":"0000-0003-2871-127X","id":"7439a258-f3c0-11ec-9501-9df22fe06720","full_name":"Matthee, Jorryt J","first_name":"Jorryt J","last_name":"Matthee"},{"full_name":"Sobral, David","first_name":"David","last_name":"Sobral"},{"full_name":"Hayes, Matthew","first_name":"Matthew","last_name":"Hayes"},{"full_name":"Pezzulli, Gabriele","last_name":"Pezzulli","first_name":"Gabriele"},{"full_name":"Gronke, Max","first_name":"Max","last_name":"Gronke"},{"full_name":"Schaerer, Daniel","last_name":"Schaerer","first_name":"Daniel"},{"full_name":"Naidu, Rohan P","first_name":"Rohan P","last_name":"Naidu"},{"last_name":"Röttgering","first_name":"Huub","full_name":"Röttgering, Huub"},{"full_name":"Calhau, João","first_name":"João","last_name":"Calhau"},{"last_name":"Paulino-Afonso","first_name":"Ana","full_name":"Paulino-Afonso, Ana"},{"full_name":"Santos, Sérgio","first_name":"Sérgio","last_name":"Santos"},{"full_name":"Amorín, Ricardo","last_name":"Amorín","first_name":"Ricardo"}],"page":"1382-1412","doi":"10.1093/mnras/stab1304","external_id":{"arxiv":["2102.07779"]},"publication_identifier":{"issn":["0035-8711"],"eissn":["1365-2966"]}}