[{"status":"public","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/2102.07779"}],"oa":1,"publication_identifier":{"eissn":["1365-2966"],"issn":["0035-8711"]},"type":"journal_article","date_published":"2021-07-01T00:00:00Z","keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: formation","galaxies: ISM","galaxies: starburst","dark ages","reionization","first stars"],"language":[{"iso":"eng"}],"month":"07","oa_version":"Preprint","publication":"Monthly Notices of the Royal Astronomical Society","extern":"1","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).","volume":505,"abstract":[{"lang":"eng","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⊙."}],"day":"01","doi":"10.1093/mnras/stab1304","arxiv":1,"external_id":{"arxiv":["2102.07779"]},"year":"2021","citation":{"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.","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>.","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.","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>.","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.","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>","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>"},"date_updated":"2022-08-18T10:49:00Z","article_type":"original","publisher":"Oxford University Press","quality_controlled":"1","page":"1382-1412","intvolume":"       505","title":"The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: What makes a galaxy a Lyman α emitter?","article_processing_charge":"No","date_created":"2022-07-07T09:33:39Z","publication_status":"published","issue":"1","author":[{"last_name":"Matthee","first_name":"Jorryt J","full_name":"Matthee, Jorryt J","orcid":"0000-0003-2871-127X","id":"7439a258-f3c0-11ec-9501-9df22fe06720"},{"first_name":"David","last_name":"Sobral","full_name":"Sobral, David"},{"last_name":"Hayes","first_name":"Matthew","full_name":"Hayes, Matthew"},{"full_name":"Pezzulli, Gabriele","first_name":"Gabriele","last_name":"Pezzulli"},{"last_name":"Gronke","first_name":"Max","full_name":"Gronke, Max"},{"last_name":"Schaerer","first_name":"Daniel","full_name":"Schaerer, Daniel"},{"full_name":"Naidu, Rohan P","last_name":"Naidu","first_name":"Rohan P"},{"full_name":"Röttgering, Huub","last_name":"Röttgering","first_name":"Huub"},{"last_name":"Calhau","first_name":"João","full_name":"Calhau, João"},{"full_name":"Paulino-Afonso, Ana","first_name":"Ana","last_name":"Paulino-Afonso"},{"full_name":"Santos, Sérgio","first_name":"Sérgio","last_name":"Santos"},{"first_name":"Ricardo","last_name":"Amorín","full_name":"Amorín, Ricardo"}],"scopus_import":"1","_id":"11523"},{"oa":1,"publication_identifier":{"eissn":["1365-2966"],"issn":["0035-8711"]},"type":"journal_article","date_published":"2018-06-01T00:00:00Z","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","status":"public","main_file_link":[{"url":"https://arxiv.org/abs/1802.10102","open_access":"1"}],"month":"06","oa_version":"Preprint","publication":"Monthly Notices of the Royal Astronomical Society","keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: active","galaxies: evolution","galaxies: high-redshift","galaxies: ISM","galaxies: starburst","cosmology: observations"],"language":[{"iso":"eng"}],"abstract":[{"lang":"eng","text":"Deep narrow-band surveys have revealed a large population of faint Ly α emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources (⁠LLyα≳1042.7 erg s−1; LLyα≳L∗Lyα⁠). Here we present the spectroscopic follow-up of 21 luminous LAEs at z ∼ 2–3 found with panoramic narrow-band surveys over five independent extragalactic fields (≈4 × 106 Mpc3 surveyed at z ∼ 2.2 and z ∼ 3.1). We use WHT/ISIS, Keck/DEIMOS, and VLT/X-SHOOTER to study these sources using high ionization UV lines. Luminous LAEs at z ∼ 2–3 have blue UV slopes (⁠β=−2.0+0.3−0.1⁠) and high Ly α escape fractions (⁠50+20−15 per cent) and span five orders of magnitude in UV luminosity (MUV ≈ −19 to −24). Many (70 per cent) show at least one high ionization rest-frame UV line such as C IV, N V, C III], He II or O III], typically blue-shifted by ≈100–200 km s−1 relative to Ly α. Their Ly α profiles reveal a wide variety of shapes, including significant blue-shifted components and widths from 200 to 4000 km s−1. Overall, 60 ± 11  per cent appear to be active galactic nucleus (AGN) dominated, and at LLyα > 1043.3 erg s−1 and/or MUV < −21.5 virtually all LAEs are AGNs with high ionization parameters (log U = 0.6 ± 0.5) and with metallicities of ≈0.5 − 1 Z⊙. Those lacking signatures of AGNs (40 ± 11  per cent) have lower ionization parameters (⁠logU=−3.0+1.6−0.9 and log ξion = 25.4 ± 0.2) and are apparently metal-poor sources likely powered by young, dust-poor ‘maximal’ starbursts. Our results show that luminous LAEs at z ∼ 2–3 are a diverse population and that 2×L∗Lyα and 2×M∗UV mark a sharp transition in the nature of LAEs, from star formation dominated to AGN dominated."}],"day":"01","arxiv":1,"doi":"10.1093/mnras/sty782","external_id":{"arxiv":["1802.10102"]},"year":"2018","citation":{"ista":"Sobral D, Matthee JJ, Darvish B, Smail I, Best PN, Alegre L, Röttgering H, Mobasher B, Paulino-Afonso A, Stroe A, Oteo I. 2018. The nature of luminous Ly α emitters at z ∼ 2–3: Maximal dust-poor starbursts and highly ionizing AGN. Monthly Notices of the Royal Astronomical Society. 477(2), 2817–2840.","short":"D. Sobral, J.J. Matthee, B. Darvish, I. Smail, P.N. Best, L. Alegre, H. Röttgering, B. Mobasher, A. Paulino-Afonso, A. Stroe, I. Oteo, Monthly Notices of the Royal Astronomical Society 477 (2018) 2817–2840.","mla":"Sobral, David, et al. “The Nature of Luminous Ly α Emitters at z ∼ 2–3: Maximal Dust-Poor Starbursts and Highly Ionizing AGN.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 477, no. 2, Oxford University Press, 2018, pp. 2817–40, doi:<a href=\"https://doi.org/10.1093/mnras/sty782\">10.1093/mnras/sty782</a>.","chicago":"Sobral, David, Jorryt J Matthee, Behnam Darvish, Ian Smail, Philip N Best, Lara Alegre, Huub Röttgering, et al. “The Nature of Luminous Ly α Emitters at z ∼ 2–3: Maximal Dust-Poor Starbursts and Highly Ionizing AGN.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2018. <a href=\"https://doi.org/10.1093/mnras/sty782\">https://doi.org/10.1093/mnras/sty782</a>.","ieee":"D. Sobral <i>et al.</i>, “The nature of luminous Ly α emitters at z ∼ 2–3: Maximal dust-poor starbursts and highly ionizing AGN,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 477, no. 2. Oxford University Press, pp. 2817–2840, 2018.","ama":"Sobral D, Matthee JJ, Darvish B, et al. The nature of luminous Ly α emitters at z ∼ 2–3: Maximal dust-poor starbursts and highly ionizing AGN. <i>Monthly Notices of the Royal Astronomical Society</i>. 2018;477(2):2817-2840. doi:<a href=\"https://doi.org/10.1093/mnras/sty782\">10.1093/mnras/sty782</a>","apa":"Sobral, D., Matthee, J. J., Darvish, B., Smail, I., Best, P. N., Alegre, L., … Oteo, I. (2018). The nature of luminous Ly α emitters at z ∼ 2–3: Maximal dust-poor starbursts and highly ionizing AGN. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href=\"https://doi.org/10.1093/mnras/sty782\">https://doi.org/10.1093/mnras/sty782</a>"},"date_updated":"2022-08-19T07:01:08Z","extern":"1","acknowledgement":"We thank the anonymous reviewer for their timely and constructive comments that greatly helped us to improve the manuscript. DS acknowledges financial support from the Netherlands Organization for Scientific research (NWO) through a Veni fellowship and from Lancaster University through an Early Career Internal Grant A100679. JM acknowledges the support of a Huygens PhD fellowship from Leiden University. BD acknowledges financial support from NASA through the Astrophysics Data Analysis Program (ADAP), grant number NNX12AE20G, and the National Science Foundation, grant number 1716907. IRS acknowledges support from the ERC Advanced Grant DUSTYGAL (321334), STFC (ST/P000541/1), and a Royal Society/Wolfson Merit Award. PNB is grateful for support from STFC via grant ST/M001229/1. We thank Anne Verhamme, Kimihiko Nakajima, Ryan Trainor, Sangeeta Malhotra, Max Gronke, James Rhoads, Fang Xia An, Matthew Hayes, Takashi Kojima, Mark Dijkstra, and Anne Jaskot for many helpful and engaging discussions, particularly during the SnowCLAW Ly α workshop. We thank Bruno Ribeiro, Stephane Charlot, and Joseph Caruana for comments on the manuscript. The authors would also like to thank Ingrid Tengs, Meg Singleton, Ali Khostovan, and Sara Perez for participating in part of the observations. We also thank Joao Calhau, Leah Morabito, Sergio Santos, and Aayush Saxena for their assistance with the narrow-band observations which allowed to select some of the sour ces. Based on observations obtained with the William Herschel Telescope, program: W16AN004; the Very Large Telescope, programs: 098.A-0819 & 099.A-0254; and the Keck II telescope, program: C267D. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme IDs 294.A-5018, 294.A-5039, 092.A-0786, 093.A-0561, 097.A-0943, 098.A-0819, 099.A-0254 and 179.A-2005. The authors acknowledge the award of service time (SW2014b20) on the 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. The authors would also like to thank all the extremely helpful observatory staff that have greatly contributed towards our observations, particularly Fiona Riddick, Lilian Dominguez, Florencia Jimenez, and Ian Skillen. We have benefited greatly from the publicly available programming language PYTHON, including the NUMPY & SCIPY (Van Der Walt, Colbert & Varoquaux 2011; Jones et al. 2001), MATPLOTLIB (Hunter 2007), ASTROPY (Astropy Collaboration et al. 2013), and the TOPCAT analysis program (Taylor 2013). This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France.","volume":477,"intvolume":"       477","title":"The nature of luminous Ly α emitters at z ∼ 2–3: Maximal dust-poor starbursts and highly ionizing AGN","date_created":"2022-07-12T07:18:02Z","article_processing_charge":"No","publication_status":"published","issue":"2","author":[{"first_name":"David","last_name":"Sobral","full_name":"Sobral, David"},{"first_name":"Jorryt J","last_name":"Matthee","orcid":"0000-0003-2871-127X","full_name":"Matthee, Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720"},{"last_name":"Darvish","first_name":"Behnam","full_name":"Darvish, Behnam"},{"full_name":"Smail, Ian","last_name":"Smail","first_name":"Ian"},{"last_name":"Best","first_name":"Philip N","full_name":"Best, Philip N"},{"full_name":"Alegre, Lara","first_name":"Lara","last_name":"Alegre"},{"first_name":"Huub","last_name":"Röttgering","full_name":"Röttgering, Huub"},{"first_name":"Bahram","last_name":"Mobasher","full_name":"Mobasher, Bahram"},{"last_name":"Paulino-Afonso","first_name":"Ana","full_name":"Paulino-Afonso, Ana"},{"full_name":"Stroe, Andra","first_name":"Andra","last_name":"Stroe"},{"first_name":"Iván","last_name":"Oteo","full_name":"Oteo, Iván"}],"scopus_import":"1","_id":"11557","article_type":"original","publisher":"Oxford University Press","quality_controlled":"1","page":"2817-2840"}]