[{"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/2007.01878"}],"article_number":"A118","year":"2020","doi":"10.1051/0004-6361/202038133","external_id":{"arxiv":["2007.01878"]},"title":"The MUSE Hubble Ultra Deep Field Survey: XV. The mean rest-UV spectra of Lyα emitters at z > 3","volume":641,"date_updated":"2022-07-19T09:35:43Z","oa":1,"article_processing_charge":"No","arxiv":1,"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","acknowledgement":"We thank Margherita Talia, Stéphane Charlot, Adele Plat and Alba Vidal-García for helpful discussions. This work is supported by the ERC advanced grant 339659-MUSICOS (R. Bacon). AF acknowledges the support from grant PRIN MIUR 2017 20173ML3WW. MVM and JP would like to thank the Leiden/ESA Astrophysics Program for Summer Students (LEAPS) for funding at the outset of this project. FL, HK, and AV acknowledge support from the ERC starting grant ERC-757258-TRIPLE. TH was supported by Leading Initiative for Excellent Young Researchers, MEXT, Japan. JB acknowledges support by FCT/MCTES through national funds by the grant UID/FIS/04434/2019, UIDB/04434/2020 and UIDP/04434/2020 and through the Investigador FCT Contract No. IF/01654/2014/CP1215/CT0003. HI acknowledges support from JSPS KAKENHI Grant Number JP19K23462. We would also like to thank the organizers and participants of the Leiden Lorentz Center workshop: Revolutionary Spectroscopy of Today as a Springboard to Webb. This work made use of several open source python packages: NUMPY (van der Walt et al. 2011), MATPLOTLIB (Hunter 2007), ASTROPY (Astropy Collaboration 2013) and MPDAF (MUSE Python Data Analysis Framework, Piqueras et al. 2019).","oa_version":"Published Version","quality_controlled":"1","_id":"11501","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"extern":"1","publication_status":"published","citation":{"ista":"Feltre A, Maseda MV, Bacon R, Pradeep J, Leclercq F, Kusakabe H, Wisotzki L, Hashimoto T, Schmidt KB, Blaizot J, Brinchmann J, Boogaard L, Cantalupo S, Carton D, Inami H, Kollatschny W, Marino RA, Matthee JJ, Nanayakkara T, Richard J, Schaye J, Tresse L, Urrutia T, Verhamme A, Weilbacher PM. 2020. The MUSE Hubble Ultra Deep Field Survey: XV. The mean rest-UV spectra of Lyα emitters at z &#62; 3. Astronomy &#38; Astrophysics. 641, A118.","short":"A. Feltre, M.V. Maseda, R. Bacon, J. Pradeep, F. Leclercq, H. Kusakabe, L. Wisotzki, T. Hashimoto, K.B. Schmidt, J. Blaizot, J. Brinchmann, L. Boogaard, S. Cantalupo, D. Carton, H. Inami, W. Kollatschny, R.A. Marino, J.J. Matthee, T. Nanayakkara, J. Richard, J. Schaye, L. Tresse, T. Urrutia, A. Verhamme, P.M. Weilbacher, Astronomy &#38; Astrophysics 641 (2020).","ama":"Feltre A, Maseda MV, Bacon R, et al. The MUSE Hubble Ultra Deep Field Survey: XV. The mean rest-UV spectra of Lyα emitters at z &#62; 3. <i>Astronomy &#38; Astrophysics</i>. 2020;641. doi:<a href=\"https://doi.org/10.1051/0004-6361/202038133\">10.1051/0004-6361/202038133</a>","mla":"Feltre, Anna, et al. “The MUSE Hubble Ultra Deep Field Survey: XV. The Mean Rest-UV Spectra of Lyα Emitters at z &#62; 3.” <i>Astronomy &#38; Astrophysics</i>, vol. 641, A118, EDP Sciences, 2020, doi:<a href=\"https://doi.org/10.1051/0004-6361/202038133\">10.1051/0004-6361/202038133</a>.","chicago":"Feltre, Anna, Michael V. Maseda, Roland Bacon, Jayadev Pradeep, Floriane Leclercq, Haruka Kusakabe, Lutz Wisotzki, et al. “The MUSE Hubble Ultra Deep Field Survey: XV. The Mean Rest-UV Spectra of Lyα Emitters at z &#62; 3.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2020. <a href=\"https://doi.org/10.1051/0004-6361/202038133\">https://doi.org/10.1051/0004-6361/202038133</a>.","apa":"Feltre, A., Maseda, M. V., Bacon, R., Pradeep, J., Leclercq, F., Kusakabe, H., … Weilbacher, P. M. (2020). The MUSE Hubble Ultra Deep Field Survey: XV. The mean rest-UV spectra of Lyα emitters at z &#62; 3. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/202038133\">https://doi.org/10.1051/0004-6361/202038133</a>","ieee":"A. Feltre <i>et al.</i>, “The MUSE Hubble Ultra Deep Field Survey: XV. The mean rest-UV spectra of Lyα emitters at z &#62; 3,” <i>Astronomy &#38; Astrophysics</i>, vol. 641. EDP Sciences, 2020."},"author":[{"first_name":"Anna","last_name":"Feltre","full_name":"Feltre, Anna"},{"first_name":"Michael V.","last_name":"Maseda","full_name":"Maseda, Michael V."},{"full_name":"Bacon, Roland","last_name":"Bacon","first_name":"Roland"},{"last_name":"Pradeep","full_name":"Pradeep, Jayadev","first_name":"Jayadev"},{"last_name":"Leclercq","full_name":"Leclercq, Floriane","first_name":"Floriane"},{"first_name":"Haruka","last_name":"Kusakabe","full_name":"Kusakabe, Haruka"},{"full_name":"Wisotzki, Lutz","last_name":"Wisotzki","first_name":"Lutz"},{"full_name":"Hashimoto, Takuya","last_name":"Hashimoto","first_name":"Takuya"},{"last_name":"Schmidt","full_name":"Schmidt, Kasper B.","first_name":"Kasper B."},{"first_name":"Jeremy","full_name":"Blaizot, Jeremy","last_name":"Blaizot"},{"first_name":"Jarle","full_name":"Brinchmann, Jarle","last_name":"Brinchmann"},{"last_name":"Boogaard","full_name":"Boogaard, Leindert","first_name":"Leindert"},{"last_name":"Cantalupo","full_name":"Cantalupo, Sebastiano","first_name":"Sebastiano"},{"first_name":"David","last_name":"Carton","full_name":"Carton, David"},{"first_name":"Hanae","full_name":"Inami, Hanae","last_name":"Inami"},{"full_name":"Kollatschny, Wolfram","last_name":"Kollatschny","first_name":"Wolfram"},{"first_name":"Raffaella A.","last_name":"Marino","full_name":"Marino, Raffaella A."},{"id":"7439a258-f3c0-11ec-9501-9df22fe06720","orcid":"0000-0003-2871-127X","full_name":"Matthee, Jorryt J","last_name":"Matthee","first_name":"Jorryt J"},{"first_name":"Themiya","last_name":"Nanayakkara","full_name":"Nanayakkara, Themiya"},{"first_name":"Johan","last_name":"Richard","full_name":"Richard, Johan"},{"first_name":"Joop","last_name":"Schaye","full_name":"Schaye, Joop"},{"first_name":"Laurence","full_name":"Tresse, Laurence","last_name":"Tresse"},{"first_name":"Tanya","last_name":"Urrutia","full_name":"Urrutia, Tanya"},{"full_name":"Verhamme, Anne","last_name":"Verhamme","first_name":"Anne"},{"first_name":"Peter M.","full_name":"Weilbacher, Peter M.","last_name":"Weilbacher"}],"keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: evolution / galaxies: high-redshift / ISM: lines and bands / ultraviolet: ISM / ultraviolet: galaxies"],"abstract":[{"text":"We investigated the ultraviolet (UV) spectral properties of faint Lyman-α emitters (LAEs) in the redshift range 2.9 ≤ z ≤ 4.6, and we provide material to prepare future observations of the faint Universe. We used data from the MUSE Hubble Ultra Deep Survey to construct mean rest-frame spectra of continuum-faint (median MUV of −18 and down to MUV of −16), low stellar mass (median value of 108.4 M⊙ and down to 107 M⊙) LAEs at redshift z ≳ 3. We computed various averaged spectra of LAEs, subsampled on the basis of their observational (e.g., Lyα strength, UV magnitude and spectral slope) and physical (e.g., stellar mass and star-formation rate) properties. We searched for UV spectral features other than Lyα, such as higher ionization nebular emission lines and absorption features. We successfully observed the O III]λ1666 and [C III]λ1907+C III]λ1909 collisionally excited emission lines and the He IIλ1640 recombination feature, as well as the resonant C IVλλ1548,1551 doublet either in emission or P-Cygni. We compared the observed spectral properties of the different mean spectra and find the emission lines to vary with the observational and physical properties of the LAEs. In particular, the mean spectra of LAEs with larger Lyα equivalent widths, fainter UV magnitudes, bluer UV spectral slopes, and lower stellar masses show the strongest nebular emission. The line ratios of these lines are similar to those measured in the spectra of local metal-poor galaxies, while their equivalent widths are weaker compared to the handful of extreme values detected in individual spectra of z >  2 galaxies. This suggests that weak UV features are likely ubiquitous in high z, low-mass, and faint LAEs. We publicly released the stacked spectra, as they can serve as empirical templates for the design of future observations, such as those with the James Webb Space Telescope and the Extremely Large Telescope.","lang":"eng"}],"date_created":"2022-07-06T09:38:16Z","date_published":"2020-09-18T00:00:00Z","article_type":"original","month":"09","language":[{"iso":"eng"}],"publisher":"EDP Sciences","scopus_import":"1","publication":"Astronomy & Astrophysics","type":"journal_article","day":"18","status":"public","intvolume":"       641"},{"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/2003.12083"}],"article_number":"A12","title":"The MUSE Hubble Ultra Deep Field Survey: XIV. Evolution of the Lyα emitter fraction from z = 3 to z = 6","external_id":{"arxiv":["2003.12083"]},"year":"2020","doi":"10.1051/0004-6361/201937340","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","acknowledgement":"We thank the anonymous referee for constructive comments and suggestions. We would like to express our gratitude to Stephane De Barros and Pablo Arrabal Haro for kindly providing their data plotted in Figs. 1, 2, and 8. We are grateful to Kazuhiro Shimasaku, Masami Ouchi, Rieko Momose, Daniel Schaerer, Hidenobu Yajima, Taku Okamura, Makoto Ando, and Hinako Goto for giving insightful comments and suggestions. This work is based on observations taken by VLT, which is operated by European Southern Observatory. This research made use of Astropy (http://www.astropy.org), which is a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018), MARZ, MPDAF, and matplotlib (Hunter 2007). H.K. acknowledges support from Japan Society for the Promotion of Science (JSPS) through the JSPS Research Fellowship for Young Scientists and Overseas Challenge Program for Young Researchers. AV acknowledges support from the ERC starting grant 757258-TRIPLE and the SNF Professorship 176808-TRIPLE. This work was supported by the project FOGHAR (Agence Nationale de la Recherche, ANR-13-BS05-0010-02). JB acknowledges support from the ORAGE project from the Agence Nationale de la Recherche under grant ANR-14-CE33-0016-03. JR acknowledges support from the ERC starting grant 336736-CALENDS. T. H. acknowledges supports by the Grant-inAid for Scientic Research 19J01620.","quality_controlled":"1","oa_version":"Published Version","_id":"11503","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"extern":"1","volume":638,"date_updated":"2022-07-19T09:35:20Z","oa":1,"article_processing_charge":"No","arxiv":1,"author":[{"first_name":"Haruka","last_name":"Kusakabe","full_name":"Kusakabe, Haruka"},{"first_name":"Jérémy","full_name":"Blaizot, Jérémy","last_name":"Blaizot"},{"first_name":"Thibault","full_name":"Garel, Thibault","last_name":"Garel"},{"first_name":"Anne","last_name":"Verhamme","full_name":"Verhamme, Anne"},{"last_name":"Bacon","full_name":"Bacon, Roland","first_name":"Roland"},{"full_name":"Richard, Johan","last_name":"Richard","first_name":"Johan"},{"first_name":"Takuya","full_name":"Hashimoto, Takuya","last_name":"Hashimoto"},{"full_name":"Inami, Hanae","last_name":"Inami","first_name":"Hanae"},{"last_name":"Conseil","full_name":"Conseil, Simon","first_name":"Simon"},{"last_name":"Guiderdoni","full_name":"Guiderdoni, Bruno","first_name":"Bruno"},{"full_name":"Drake, Alyssa B.","last_name":"Drake","first_name":"Alyssa B."},{"first_name":"Edmund","full_name":"Christian Herenz, Edmund","last_name":"Christian Herenz"},{"full_name":"Schaye, Joop","last_name":"Schaye","first_name":"Joop"},{"last_name":"Oesch","full_name":"Oesch, Pascal","first_name":"Pascal"},{"orcid":"0000-0003-2871-127X","full_name":"Matthee, Jorryt J","last_name":"Matthee","first_name":"Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720"},{"first_name":"Raffaella","full_name":"Anna Marino, Raffaella","last_name":"Anna Marino"},{"first_name":"Kasper","full_name":"Borello Schmidt, Kasper","last_name":"Borello Schmidt"},{"last_name":"Pelló","full_name":"Pelló, Roser","first_name":"Roser"},{"last_name":"Maseda","full_name":"Maseda, Michael","first_name":"Michael"},{"first_name":"Floriane","full_name":"Leclercq, Floriane","last_name":"Leclercq"},{"first_name":"Josephine","full_name":"Kerutt, Josephine","last_name":"Kerutt"},{"last_name":"Mahler","full_name":"Mahler, Guillaume","first_name":"Guillaume"}],"keyword":["Space and Planetary Science","Astronomy and Astrophysics","dark ages / reionization / first stars / early Universe / cosmology: observations / galaxies: evolution / galaxies: high-redshift / intergalactic medium"],"abstract":[{"text":"Context. The Lyα emitter (LAE) fraction, XLAE, is a potentially powerful probe of the evolution of the intergalactic neutral hydrogen gas fraction. However, uncertainties in the measurement of XLAE are still under debate.\r\nAims. Thanks to deep data obtained with the integral field spectrograph Multi Unit Spectroscopic Explorer (MUSE), we can measure the evolution of the LAE fraction homogeneously over a wide redshift range of z ≈ 3–6 for UV-faint galaxies (down to UV magnitudes of M1500 ≈ −17.75). This is a significantly fainter range than in former studies (M1500 ≤ −18.75) and it allows us to probe the bulk of the population of high-redshift star-forming galaxies.\r\nMethods. We constructed a UV-complete photometric-redshift sample following UV luminosity functions and measured the Lyα emission with MUSE using the latest (second) data release from the MUSE Hubble Ultra Deep Field Survey.\r\nResults. We derived the redshift evolution of XLAE for M1500 ∈ [ − 21.75; −17.75] for the first time with a equivalent width range EW(Lyα) ≥ 65 Å and found low values of XLAE ≲ 30% at z ≲ 6. The best-fit linear relation is XLAE = 0.07+0.06−0.03z − 0.22+0.12−0.24. For M1500 ∈ [ − 20.25; −18.75] and EW(Lyα) ≥ 25 Å, our XLAE values are consistent with those in the literature within 1σ at z ≲ 5, but our median values are systematically lower than reported values over the whole redshift range. In addition, we do not find a significant dependence of XLAE on M1500 for EW(Lyα) ≥ 50 Å at z ≈ 3–4, in contrast with previous work. The differences in XLAE mainly arise from selection biases for Lyman Break Galaxies (LBGs) in the literature: UV-faint LBGs are more easily selected if they have strong Lyα emission, hence XLAE is biased towards higher values when those samples are used.\r\nConclusions. Our results suggest either a lower increase of XLAE towards z ≈ 6 than previously suggested, or even a turnover of XLAE at z ≈ 5.5, which may be the signature of a late or patchy reionization process. We compared our results with predictions from a cosmological galaxy evolution model. We find that a model with a bursty star formation (SF) can reproduce our observed LAE fractions much better than models where SF is a smooth function of time.","lang":"eng"}],"publication_status":"published","citation":{"mla":"Kusakabe, Haruka, et al. “The MUSE Hubble Ultra Deep Field Survey: XIV. Evolution of the Lyα Emitter Fraction from z = 3 to z = 6.” <i>Astronomy &#38; Astrophysics</i>, vol. 638, A12, EDP Sciences, 2020, doi:<a href=\"https://doi.org/10.1051/0004-6361/201937340\">10.1051/0004-6361/201937340</a>.","ama":"Kusakabe H, Blaizot J, Garel T, et al. The MUSE Hubble Ultra Deep Field Survey: XIV. Evolution of the Lyα emitter fraction from z = 3 to z = 6. <i>Astronomy &#38; Astrophysics</i>. 2020;638. doi:<a href=\"https://doi.org/10.1051/0004-6361/201937340\">10.1051/0004-6361/201937340</a>","ista":"Kusakabe H, Blaizot J, Garel T, Verhamme A, Bacon R, Richard J, Hashimoto T, Inami H, Conseil S, Guiderdoni B, Drake AB, Christian Herenz E, Schaye J, Oesch P, Matthee JJ, Anna Marino R, Borello Schmidt K, Pelló R, Maseda M, Leclercq F, Kerutt J, Mahler G. 2020. The MUSE Hubble Ultra Deep Field Survey: XIV. Evolution of the Lyα emitter fraction from z = 3 to z = 6. Astronomy &#38; Astrophysics. 638, A12.","short":"H. Kusakabe, J. Blaizot, T. Garel, A. Verhamme, R. Bacon, J. Richard, T. Hashimoto, H. Inami, S. Conseil, B. Guiderdoni, A.B. Drake, E. Christian Herenz, J. Schaye, P. Oesch, J.J. Matthee, R. Anna Marino, K. Borello Schmidt, R. Pelló, M. Maseda, F. Leclercq, J. Kerutt, G. Mahler, Astronomy &#38; Astrophysics 638 (2020).","apa":"Kusakabe, H., Blaizot, J., Garel, T., Verhamme, A., Bacon, R., Richard, J., … Mahler, G. (2020). The MUSE Hubble Ultra Deep Field Survey: XIV. Evolution of the Lyα emitter fraction from z = 3 to z = 6. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/201937340\">https://doi.org/10.1051/0004-6361/201937340</a>","ieee":"H. Kusakabe <i>et al.</i>, “The MUSE Hubble Ultra Deep Field Survey: XIV. Evolution of the Lyα emitter fraction from z = 3 to z = 6,” <i>Astronomy &#38; Astrophysics</i>, vol. 638. EDP Sciences, 2020.","chicago":"Kusakabe, Haruka, Jérémy Blaizot, Thibault Garel, Anne Verhamme, Roland Bacon, Johan Richard, Takuya Hashimoto, et al. “The MUSE Hubble Ultra Deep Field Survey: XIV. Evolution of the Lyα Emitter Fraction from z = 3 to z = 6.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2020. <a href=\"https://doi.org/10.1051/0004-6361/201937340\">https://doi.org/10.1051/0004-6361/201937340</a>."},"date_created":"2022-07-06T09:50:48Z","language":[{"iso":"eng"}],"publisher":"EDP Sciences","scopus_import":"1","article_type":"original","date_published":"2020-06-03T00:00:00Z","month":"06","publication":"Astronomy & Astrophysics","status":"public","intvolume":"       638","type":"journal_article","day":"03"},{"date_created":"2022-07-06T09:07:06Z","language":[{"iso":"eng"}],"publisher":"EDP Sciences","scopus_import":"1","date_published":"2019-04-16T00:00:00Z","article_type":"original","month":"04","publication":"Astronomy & Astrophysics","status":"public","intvolume":"       648","type":"journal_article","day":"16","related_material":{"link":[{"url":"https://doi.org/10.1051/0004-6361/201834565e","relation":"erratum"}]},"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1902.05960"}],"article_number":"A89","title":"Exploring He II λ1640 emission line properties at z ∼2−4","external_id":{"arxiv":["1902.05960"]},"year":"2019","doi":"10.1051/0004-6361/201834565","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","acknowledgement":"The authors wish to thank the referee for constructive comments that improved the paper substantially. We thank the BPASS team for making the stellar population models available. We thank Elizabeth Stanway, Claus Leitherer, Daniel Schaerer, Jorick Vink, and Nell Byler for insightful discussions. We thank the Lorentz Centre and the scientific organizers of the Characterizing galaxies with spectroscopy with a view for JWST workshop held at the Lorentz Centre in 2017 October, which promoted useful discussions in the wider community. TN, JB, and RB acknowledges the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) top grant TOP1.16.057. AF acknowledges support from the ERC via an Advanced Grant under grant agreement no. 339659-MUSICOS. JB acknowledges support by Fundação para a Ciência e a Tecnologia (FCT) through national funds (UID/FIS/04434/2013) and Investigador FCT contract IF/01654/2014/CP1215/CT0003, and by FEDER through COMPETE2020 (POCI-01-0145-FEDER-007672). JR acknowledges support from the ERC Starting grant 336736 (CALENDS). This research made use of astropy (http://www.astropy.org) a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018) and pandas (McKinney 2010). Figures were generated using matplotlib (Hunter 2007) and seaborn (https://seaborn.pydata.org). Facilities: VLT (MUSE).","oa_version":"Published Version","quality_controlled":"1","_id":"11499","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"extern":"1","date_updated":"2022-07-19T09:36:08Z","volume":648,"oa":1,"article_processing_charge":"No","arxiv":1,"author":[{"full_name":"Nanayakkara, Themiya","last_name":"Nanayakkara","first_name":"Themiya"},{"first_name":"Jarle","last_name":"Brinchmann","full_name":"Brinchmann, Jarle"},{"last_name":"Boogaard","full_name":"Boogaard, Leindert","first_name":"Leindert"},{"first_name":"Rychard","full_name":"Bouwens, Rychard","last_name":"Bouwens"},{"full_name":"Cantalupo, Sebastiano","last_name":"Cantalupo","first_name":"Sebastiano"},{"first_name":"Anna","full_name":"Feltre, Anna","last_name":"Feltre"},{"first_name":"Wolfram","full_name":"Kollatschny, Wolfram","last_name":"Kollatschny"},{"first_name":"Raffaella Anna","full_name":"Marino, Raffaella Anna","last_name":"Marino"},{"last_name":"Maseda","full_name":"Maseda, Michael","first_name":"Michael"},{"first_name":"Jorryt J","last_name":"Matthee","full_name":"Matthee, Jorryt J","orcid":"0000-0003-2871-127X","id":"7439a258-f3c0-11ec-9501-9df22fe06720"},{"full_name":"Paalvast, Mieke","last_name":"Paalvast","first_name":"Mieke"},{"last_name":"Richard","full_name":"Richard, Johan","first_name":"Johan"},{"first_name":"Anne","full_name":"Verhamme, Anne","last_name":"Verhamme"}],"keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: ISM / galaxies: star formation / galaxies: evolution / galaxies: high-redshift"],"abstract":[{"text":"Deep optical spectroscopic surveys of galaxies provide a unique opportunity to investigate rest-frame ultra-violet (UV) emission line properties of galaxies at z ∼ 2 − 4.5. Here we combine VLT/MUSE Guaranteed Time Observations of the Hubble Deep Field South, Ultra Deep Field, COSMOS, and several quasar fields with other publicly available data from VLT/VIMOS and VLT/FORS2 to construct a catalogue of He II λ1640 emitters at z ≳ 2. The deepest areas of our MUSE pointings reach a 3σ line flux limit of 3.1 × 10−19 erg s−1 cm−2. After discarding broad-line active galactic nuclei, we find 13 He II λ1640 detections from MUSE with a median MUV = −20.1 and 21 tentative He II λ1640 detections from other public surveys. Excluding Lyα, all except two galaxies in our sample show at least one other rest-UV emission line, with C III] λ1907, λ1909 being the most prominent. We use multi-wavelength data available in the Hubble legacy fields to derive basic galaxy properties of our sample through spectral energy distribution fitting techniques. Taking advantage of the high-quality spectra obtained by MUSE (∼10 − 30 h of exposure time per pointing), we use photo-ionisation models to study the rest-UV emission line diagnostics of the He II λ1640 emitters. Line ratios of our sample can be reproduced by moderately sub-solar photo-ionisation models, however, we find that including effects of binary stars lead to degeneracies in most free parameters. Even after considering extra ionising photons produced by extreme sub-solar metallicity binary stellar models, photo-ionisation models are unable to reproduce rest-frame He II λ1640 equivalent widths (∼0.2 − 10 Å), thus additional mechanisms are necessary in models to match the observed He II λ1640 properties.","lang":"eng"}],"publication_status":"published","citation":{"ama":"Nanayakkara T, Brinchmann J, Boogaard L, et al. Exploring He II λ1640 emission line properties at z ∼2−4. <i>Astronomy &#38; Astrophysics</i>. 2019;648. doi:<a href=\"https://doi.org/10.1051/0004-6361/201834565\">10.1051/0004-6361/201834565</a>","mla":"Nanayakkara, Themiya, et al. “Exploring He II Λ1640 Emission Line Properties at z ∼2−4.” <i>Astronomy &#38; Astrophysics</i>, vol. 648, A89, EDP Sciences, 2019, doi:<a href=\"https://doi.org/10.1051/0004-6361/201834565\">10.1051/0004-6361/201834565</a>.","ista":"Nanayakkara T, Brinchmann J, Boogaard L, Bouwens R, Cantalupo S, Feltre A, Kollatschny W, Marino RA, Maseda M, Matthee JJ, Paalvast M, Richard J, Verhamme A. 2019. Exploring He II λ1640 emission line properties at z ∼2−4. Astronomy &#38; Astrophysics. 648, A89.","short":"T. Nanayakkara, J. Brinchmann, L. Boogaard, R. Bouwens, S. Cantalupo, A. Feltre, W. Kollatschny, R.A. Marino, M. Maseda, J.J. Matthee, M. Paalvast, J. Richard, A. Verhamme, Astronomy &#38; Astrophysics 648 (2019).","apa":"Nanayakkara, T., Brinchmann, J., Boogaard, L., Bouwens, R., Cantalupo, S., Feltre, A., … Verhamme, A. (2019). Exploring He II λ1640 emission line properties at z ∼2−4. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/201834565\">https://doi.org/10.1051/0004-6361/201834565</a>","ieee":"T. Nanayakkara <i>et al.</i>, “Exploring He II λ1640 emission line properties at z ∼2−4,” <i>Astronomy &#38; Astrophysics</i>, vol. 648. EDP Sciences, 2019.","chicago":"Nanayakkara, Themiya, Jarle Brinchmann, Leindert Boogaard, Rychard Bouwens, Sebastiano Cantalupo, Anna Feltre, Wolfram Kollatschny, et al. “Exploring He II Λ1640 Emission Line Properties at z ∼2−4.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2019. <a href=\"https://doi.org/10.1051/0004-6361/201834565\">https://doi.org/10.1051/0004-6361/201834565</a>."}},{"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1803.08923"}],"article_number":"A157","doi":"10.1051/0004-6361/201833075","year":"2019","title":"Predicting Lyα escape fractions with a simple observable: Lyα in emission as an empirically calibrated star formation rate indicator","external_id":{"arxiv":["1803.08923"]},"oa":1,"volume":623,"date_updated":"2022-07-19T09:37:20Z","article_processing_charge":"No","arxiv":1,"acknowledgement":"We thank the anonymous referees for multiple comments and suggestions which have improved the manuscript. JM acknowledges the support of a Huygens PhD fellowship from Leiden University. We have benefited greatly from the publicly available programming language PYTHON, including the NUMPY & SCIPY (Van Der Walt et al. 2011; Jones et al. 2001), MATPLOTLIB (Hunter 2007) and ASTROPY (Astropy Collaboration 2013) packages, and the TOPCAT analysis program (Taylor 2013). The results and samples of LAEs used for this paper are publicly available (see e.g. Sobral et al. 2017, 2018a) and we also provide the toy model used as a PYTHON script.","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","oa_version":"Published Version","quality_controlled":"1","_id":"11507","extern":"1","publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"publication_status":"published","citation":{"mla":"Sobral, David, and Jorryt J. Matthee. “Predicting Lyα Escape Fractions with a Simple Observable: Lyα in Emission as an Empirically Calibrated Star Formation Rate Indicator.” <i>Astronomy &#38; Astrophysics</i>, vol. 623, A157, EDP Sciences, 2019, doi:<a href=\"https://doi.org/10.1051/0004-6361/201833075\">10.1051/0004-6361/201833075</a>.","ama":"Sobral D, Matthee JJ. Predicting Lyα escape fractions with a simple observable: Lyα in emission as an empirically calibrated star formation rate indicator. <i>Astronomy &#38; Astrophysics</i>. 2019;623. doi:<a href=\"https://doi.org/10.1051/0004-6361/201833075\">10.1051/0004-6361/201833075</a>","ista":"Sobral D, Matthee JJ. 2019. Predicting Lyα escape fractions with a simple observable: Lyα in emission as an empirically calibrated star formation rate indicator. Astronomy &#38; Astrophysics. 623, A157.","short":"D. Sobral, J.J. Matthee, Astronomy &#38; Astrophysics 623 (2019).","apa":"Sobral, D., &#38; Matthee, J. J. (2019). Predicting Lyα escape fractions with a simple observable: Lyα in emission as an empirically calibrated star formation rate indicator. <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href=\"https://doi.org/10.1051/0004-6361/201833075\">https://doi.org/10.1051/0004-6361/201833075</a>","ieee":"D. Sobral and J. J. Matthee, “Predicting Lyα escape fractions with a simple observable: Lyα in emission as an empirically calibrated star formation rate indicator,” <i>Astronomy &#38; Astrophysics</i>, vol. 623. EDP Sciences, 2019.","chicago":"Sobral, David, and Jorryt J Matthee. “Predicting Lyα Escape Fractions with a Simple Observable: Lyα in Emission as an Empirically Calibrated Star Formation Rate Indicator.” <i>Astronomy &#38; Astrophysics</i>. EDP Sciences, 2019. <a href=\"https://doi.org/10.1051/0004-6361/201833075\">https://doi.org/10.1051/0004-6361/201833075</a>."},"keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: high-redshift / galaxies: star formation / galaxies: statistics / galaxies: evolution / galaxies: formation / galaxies: ISM"],"author":[{"last_name":"Sobral","full_name":"Sobral, David","first_name":"David"},{"first_name":"Jorryt J","orcid":"0000-0003-2871-127X","last_name":"Matthee","full_name":"Matthee, Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720"}],"abstract":[{"text":"Lyman-α (Lyα) is intrinsically the brightest line emitted from active galaxies. While it originates from many physical processes, for star-forming galaxies the intrinsic Lyα luminosity is a direct tracer of the Lyman-continuum (LyC) radiation produced by the most massive O- and early-type B-stars (M⋆ ≳ 10 M⊙) with lifetimes of a few Myrs. As such, Lyα luminosity should be an excellent instantaneous star formation rate (SFR) indicator. However, its resonant nature and susceptibility to dust as a rest-frame UV photon makes Lyα very hard to interpret due to the uncertain Lyα escape fraction, fesc, Lyα. Here we explore results from the CAlibrating LYMan-α with Hα (CALYMHA) survey at z = 2.2, follow-up of Lyα emitters (LAEs) at z = 2.2 − 2.6 and a z ∼ 0−0.3 compilation of LAEs to directly measure fesc, Lyα with Hα. We derive a simple empirical relation that robustly retrieves fesc, Lyα as a function of Lyα rest-frame EW (EW0): fesc,Lyα = 0.0048 EW0[Å] ± 0.05 and we show that it constrains a well-defined anti-correlation between ionisation efficiency (ξion) and dust extinction in LAEs. Observed Lyα luminosities and EW0 are easy measurable quantities at high redshift, thus making our relation a practical tool to estimate intrinsic Lyα and LyC luminosities under well controlled and simple assumptions. Our results allow observed Lyα luminosities to be used to compute SFRs for LAEs at z ∼ 0−2.6 within ±0.2 dex of the Hα dust corrected SFRs. We apply our empirical SFR(Lyα,EW0) calibration to several sources at z ≥ 2.6 to find that star-forming LAEs have SFRs typically ranging from 0.1 to 20 M⊙ yr−1 and that our calibration might be even applicable for the most luminous LAEs within the epoch of re-ionisation. Our results imply high ionisation efficiencies (log10[ξion/Hz erg−1] = 25.4−25.6) and low dust content in LAEs across cosmic time, and will be easily tested with future observations with JWST which can obtain Hα and Hβ measurements for high-redshift LAEs.","lang":"eng"}],"date_created":"2022-07-06T11:08:16Z","date_published":"2019-03-26T00:00:00Z","article_type":"original","month":"03","language":[{"iso":"eng"}],"publisher":"EDP Sciences","scopus_import":"1","publication":"Astronomy & Astrophysics","type":"journal_article","day":"26","status":"public","intvolume":"       623"},{"intvolume":"       472","status":"public","day":"01","type":"journal_article","issue":"1","publication":"Monthly Notices of the Royal Astronomical Society","page":"772-787","publisher":"Oxford University Press","scopus_import":"1","language":[{"iso":"eng"}],"month":"11","date_published":"2017-11-01T00:00:00Z","article_type":"original","date_created":"2022-07-13T09:47:39Z","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."}],"keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: evolution – galaxies: high-redshift","dark ages","reionization","first stars","cosmology: observations"],"author":[{"orcid":"0000-0003-2871-127X","last_name":"Matthee","full_name":"Matthee, Jorryt J","first_name":"Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720"},{"first_name":"David","last_name":"Sobral","full_name":"Sobral, David"},{"first_name":"Behnam","last_name":"Darvish","full_name":"Darvish, Behnam"},{"last_name":"Santos","full_name":"Santos, Sérgio","first_name":"Sérgio"},{"full_name":"Mobasher, Bahram","last_name":"Mobasher","first_name":"Bahram"},{"first_name":"Ana","last_name":"Paulino-Afonso","full_name":"Paulino-Afonso, Ana"},{"first_name":"Huub","full_name":"Röttgering, Huub","last_name":"Röttgering"},{"last_name":"Alegre","full_name":"Alegre, Lara","first_name":"Lara"}],"publication_status":"published","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>","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.","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>.","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>","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>.","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.","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."},"_id":"11572","extern":"1","publication_identifier":{"eissn":["1365-2966"],"issn":["0035-8711"]},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","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).","oa_version":"Preprint","quality_controlled":"1","arxiv":1,"date_updated":"2022-08-19T08:05:37Z","volume":472,"oa":1,"article_processing_charge":"No","title":"Spectroscopic properties of luminous Ly α emitters at z ≈ 6–7 and comparison to the Lyman-break population","external_id":{"arxiv":["1706.06591"]},"year":"2017","doi":"10.1093/mnras/stx2061","main_file_link":[{"url":"https://arxiv.org/abs/1706.06591","open_access":"1"}]},{"month":"12","article_type":"original","date_published":"2013-12-03T00:00:00Z","publisher":"IOP Publishing","scopus_import":"1","language":[{"iso":"eng"}],"date_created":"2022-07-07T09:14:48Z","day":"03","type":"journal_article","intvolume":"       779","status":"public","issue":"2","publication":"The Astrophysical Journal","doi":"10.1088/0004-637x/779/2/139","year":"2013","title":"The dynamics of z=0.8 H-alpha-selected star-forming galaxies from KMOS/CF-HiZELS","external_id":{"arxiv":["1310.3822"]},"article_number":"139","main_file_link":[{"url":"https://arxiv.org/abs/1310.3822","open_access":"1"}],"publication_status":"published","citation":{"mla":"Sobral, D., et al. “The Dynamics of Z=0.8 H-Alpha-Selected Star-Forming Galaxies from KMOS/CF-HiZELS.” <i>The Astrophysical Journal</i>, vol. 779, no. 2, 139, IOP Publishing, 2013, doi:<a href=\"https://doi.org/10.1088/0004-637x/779/2/139\">10.1088/0004-637x/779/2/139</a>.","ama":"Sobral D, Swinbank AM, Stott JP, et al. The dynamics of z=0.8 H-alpha-selected star-forming galaxies from KMOS/CF-HiZELS. <i>The Astrophysical Journal</i>. 2013;779(2). doi:<a href=\"https://doi.org/10.1088/0004-637x/779/2/139\">10.1088/0004-637x/779/2/139</a>","ista":"Sobral D, Swinbank AM, Stott JP, Matthee JJ, Bower RG, Smail I, Best P, Geach JE, Sharples RM. 2013. The dynamics of z=0.8 H-alpha-selected star-forming galaxies from KMOS/CF-HiZELS. The Astrophysical Journal. 779(2), 139.","short":"D. Sobral, A.M. Swinbank, J.P. Stott, J.J. Matthee, R.G. Bower, I. Smail, P. Best, J.E. Geach, R.M. Sharples, The Astrophysical Journal 779 (2013).","ieee":"D. Sobral <i>et al.</i>, “The dynamics of z=0.8 H-alpha-selected star-forming galaxies from KMOS/CF-HiZELS,” <i>The Astrophysical Journal</i>, vol. 779, no. 2. IOP Publishing, 2013.","apa":"Sobral, D., Swinbank, A. M., Stott, J. P., Matthee, J. J., Bower, R. G., Smail, I., … Sharples, R. M. (2013). The dynamics of z=0.8 H-alpha-selected star-forming galaxies from KMOS/CF-HiZELS. <i>The Astrophysical Journal</i>. IOP Publishing. <a href=\"https://doi.org/10.1088/0004-637x/779/2/139\">https://doi.org/10.1088/0004-637x/779/2/139</a>","chicago":"Sobral, D., A. M. Swinbank, J. P. Stott, Jorryt J Matthee, R. G. Bower, Ian Smail, P. Best, J. E. Geach, and R. M. Sharples. “The Dynamics of Z=0.8 H-Alpha-Selected Star-Forming Galaxies from KMOS/CF-HiZELS.” <i>The Astrophysical Journal</i>. IOP Publishing, 2013. <a href=\"https://doi.org/10.1088/0004-637x/779/2/139\">https://doi.org/10.1088/0004-637x/779/2/139</a>."},"abstract":[{"text":"We present the spatially resolved Hα dynamics of 16 star-forming galaxies at z ∼ 0.81 using the new KMOS multi-object integral field spectrograph on the ESO Very Large Telescope. These galaxies, selected using 1.18 μm narrowband imaging from the 10 deg2 CFHT-HiZELS survey of the SA 22 hr field, are found in a ∼4 Mpc overdensity of Hα emitters and likely reside in a group/intermediate environment, but not a cluster. We confirm and identify a rich group of star-forming galaxies at z = 0.813 ± 0.003, with 13 galaxies within 1000 km s−1 of each other, and seven within a diameter of 3 Mpc. All of our galaxies are “typical” star-forming galaxies at their redshift, 0.8 ± 0.4 SFR$^*_{z = 0.8}$, spanning a range of specific star formation rates (sSFRs) of 0.2–1.1 Gyr−1 and have a median metallicity very close to solar of 12 + log(O/H) = 8.62 ± 0.06. We measure the spatially resolved Hα dynamics of the galaxies in our sample and show that 13 out of 16 galaxies can be described by rotating disks and use the data to derive inclination corrected rotation speeds of 50–275 km s−1. The fraction of disks within our sample is 75% ± 8%, consistent with previous results based on Hubble Space Telescope morphologies of Hα-selected galaxies at z ∼ 1 and confirming that disks dominate the SFR density at z ∼ 1. Our Hα galaxies are well fitted by the z ∼ 1–2 Tully–Fisher (TF) relation, confirming the evolution seen in the zero point. Apart from having, on average, higher stellar masses and lower sSFRs, our group galaxies at z = 0.81 present the same mass–metallicity and TF relation as z ∼ 1 field galaxies and are all disk galaxies.","lang":"eng"}],"keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: evolution – galaxies","high-redshift – galaxies","starburst"],"author":[{"first_name":"D.","last_name":"Sobral","full_name":"Sobral, D."},{"full_name":"Swinbank, A. M.","last_name":"Swinbank","first_name":"A. M."},{"last_name":"Stott","full_name":"Stott, J. P.","first_name":"J. P."},{"id":"7439a258-f3c0-11ec-9501-9df22fe06720","last_name":"Matthee","full_name":"Matthee, Jorryt J","orcid":"0000-0003-2871-127X","first_name":"Jorryt J"},{"first_name":"R. G.","full_name":"Bower, R. G.","last_name":"Bower"},{"first_name":"Ian","last_name":"Smail","full_name":"Smail, Ian"},{"first_name":"P.","last_name":"Best","full_name":"Best, P."},{"first_name":"J. E.","full_name":"Geach, J. E.","last_name":"Geach"},{"first_name":"R. M.","last_name":"Sharples","full_name":"Sharples, R. M."}],"arxiv":1,"volume":779,"oa":1,"date_updated":"2022-08-18T10:43:07Z","article_processing_charge":"No","_id":"11520","extern":"1","publication_identifier":{"eissn":["1538-4357"],"issn":["0004-637X"]},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","acknowledgement":"We thank the referee for many helpful comments and suggestions which greatly improved the clarity and quality of this work. D.S. acknowledges financial support from the Netherlands Organisation for Scientific research (NWO) through a Veni fellowship and also funding from the European Community Seventh Framework Programme (FP7/2007-2013) under grant agreement number RG226604 (OPTICON) which allowed access to CFHT time (proposals: 11BO29 & 12AO19). A.M.S. gratefully acknowledges an STFC Advanced Fellowship through grant number ST/H005234/1. I.R.S., J.P.S., and R.G.B. acknowledge support from the UK Science and Technology Facilities Council (STFC) under ST/I001573/1. I.R.S. acknowledges STFC (ST/J001422/1), the ERC Advanced Investigator program DUSTYGAL and a Royal Society/Wolfson Merit Award. P.N.B. acknowledges support from STFC. R.M.S. acknowledges support from the grant ST/1001573/1. The data presented here are based on observations with the KMOS spectrograph on the ESO/VLT under program 60.A-9460 and can be accessed through the ESO data archive. The authors also wish to acknowledge the help from Michael Hilker in preparing the KMOS observations.","oa_version":"Preprint","quality_controlled":"1"}]