[{"keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: high-redshift / galaxies: star formation / galaxies: statistics / galaxies: evolution / galaxies: formation / galaxies: ISM"],"publication_identifier":{"eissn":["1432-0746"],"issn":["0004-6361"]},"arxiv":1,"title":"Predicting Lyα escape fractions with a simple observable: Lyα in emission as an empirically calibrated star formation rate indicator","date_created":"2022-07-06T11:08:16Z","oa_version":"Published Version","publication_status":"published","article_processing_charge":"No","publisher":"EDP Sciences","extern":"1","oa":1,"doi":"10.1051/0004-6361/201833075","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.","author":[{"first_name":"David","last_name":"Sobral","full_name":"Sobral, David"},{"full_name":"Matthee, Jorryt J","last_name":"Matthee","id":"7439a258-f3c0-11ec-9501-9df22fe06720","first_name":"Jorryt J","orcid":"0000-0003-2871-127X"}],"volume":623,"month":"03","article_type":"original","article_number":"A157","intvolume":"       623","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","year":"2019","date_published":"2019-03-26T00:00:00Z","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1803.08923"}],"external_id":{"arxiv":["1803.08923"]},"_id":"11507","language":[{"iso":"eng"}],"abstract":[{"lang":"eng","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."}],"quality_controlled":"1","type":"journal_article","citation":{"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.","short":"D. Sobral, J.J. Matthee, Astronomy &#38; Astrophysics 623 (2019).","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>.","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>.","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.","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>"},"day":"26","status":"public","scopus_import":"1","publication":"Astronomy & Astrophysics","date_updated":"2022-07-19T09:37:20Z"},{"extern":"1","article_processing_charge":"No","publisher":"Oxford University Press","volume":476,"author":[{"last_name":"Sobral","full_name":"Sobral, David","first_name":"David"},{"last_name":"Santos","full_name":"Santos, Sérgio","first_name":"Sérgio"},{"last_name":"Matthee","full_name":"Matthee, Jorryt J","first_name":"Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720","orcid":"0000-0003-2871-127X"},{"first_name":"Ana","full_name":"Paulino-Afonso, Ana","last_name":"Paulino-Afonso"},{"full_name":"Ribeiro, Bruno","last_name":"Ribeiro","first_name":"Bruno"},{"first_name":"João","last_name":"Calhau","full_name":"Calhau, João"},{"first_name":"Ali A","last_name":"Khostovan","full_name":"Khostovan, Ali A"}],"article_type":"original","month":"06","acknowledgement":"We thank the anonymous referee for their constructive comments that helped us improve the manuscript. DS acknowledges the hospitality of the IAC and a Severo Ochoa visiting grant. SS and JC acknowledge studentships from the Lancaster University. JM acknowledges a Huygens PhD fellowship from Leiden University. APA acknowledges financial support from the Science and Technology Foundation (FCT, Portugal) through research grants UID/FIS/04434/2013 and fellowship PD/BD/52706/2014. The authors thank Alyssa Drake, Kimihiko Nakajima, Yuichi Harikane, Max Gronke, Irene Shivaei, Helmut Dannerbauer, Huub Rottgering, ¨ Marius Eide, and Masami Ouchi for many engaging and stimulating discussions. We also thank Sara Perez, Alex Bennett, and Tom Rose for their involvement in the early stages of this project. Based on data products from observations made with European Southern Observatory (ESO) Telescopes at the La Silla Paranal Observatory under ESO programme IDs 294.A-5018, 097.A 0943,\r\n098.A-0819, 099.A-0254, and 179.A-2005 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. Based on observations using the WFC on the 2.5 m INT, as part of programmes 2013AN002, 2013BN008, 2014AC88, 2014AN002, 2014BN006, 2014BC118, and 2016AN001. The INT is 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. This work is based in part on data products produced at TERAPIX available at the Canadian Astronomy Data Centre as part of the Canada–France– Hawaii Telescope Legacy Survey (CFHTLS), a collaborative project of NRC and CNRS.\r\nWe are grateful to the CFHTLS, COSMOS-UltraVISTA, and COSMOS survey teams. We are also unmeasurably thankful to the pioneering and continuous work from previous Ly α surveys’ teams. Without these previous Ly α and the wider reach legacy surveys, this research would have been impossible. We also thank the VUDS team for making available spectroscopic redshifts from data obtained with VIMOS at the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Programme 185.A-0791. Finally, the authors acknowledge the unique value of the publicly available programming language PYTHON, including the NUMPY and 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 2005). We publicly release a catalogue with all LAEs used in this paper (SC4K), so it can be freely explored by the community (see five example entries in Table A1).","oa":1,"doi":"10.1093/mnras/sty378","title":"Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6","date_created":"2022-07-12T10:41:08Z","oa_version":"Preprint","publication_identifier":{"issn":["0035-8711"],"eissn":["1365-2966"]},"arxiv":1,"keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: evolution","galaxies: formation","galaxies: high-redshift","galaxies: luminosity function","mass function","galaxies: statistics"],"publication_status":"published","issue":"4","scopus_import":"1","status":"public","page":"4725-4752","date_updated":"2022-08-19T07:04:45Z","publication":"Monthly Notices of the Royal Astronomical Society","date_published":"2018-06-01T00:00:00Z","main_file_link":[{"url":"https://arxiv.org/abs/1712.04451","open_access":"1"}],"intvolume":"       476","year":"2018","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","citation":{"mla":"Sobral, David, et al. “Slicing COSMOS with SC4K: The Evolution of Typical Ly α Emitters and the Ly α Escape Fraction from z ∼ 2 to 6.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 476, no. 4, Oxford University Press, 2018, pp. 4725–52, doi:<a href=\"https://doi.org/10.1093/mnras/sty378\">10.1093/mnras/sty378</a>.","ieee":"D. Sobral <i>et al.</i>, “Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 476, no. 4. Oxford University Press, pp. 4725–4752, 2018.","short":"D. Sobral, S. Santos, J.J. Matthee, A. Paulino-Afonso, B. Ribeiro, J. Calhau, A.A. Khostovan, Monthly Notices of the Royal Astronomical Society 476 (2018) 4725–4752.","apa":"Sobral, D., Santos, S., Matthee, J. J., Paulino-Afonso, A., Ribeiro, B., Calhau, J., &#38; Khostovan, A. A. (2018). Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href=\"https://doi.org/10.1093/mnras/sty378\">https://doi.org/10.1093/mnras/sty378</a>","ama":"Sobral D, Santos S, Matthee JJ, et al. Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6. <i>Monthly Notices of the Royal Astronomical Society</i>. 2018;476(4):4725-4752. doi:<a href=\"https://doi.org/10.1093/mnras/sty378\">10.1093/mnras/sty378</a>","ista":"Sobral D, Santos S, Matthee JJ, Paulino-Afonso A, Ribeiro B, Calhau J, Khostovan AA. 2018. Slicing COSMOS with SC4K: The evolution of typical Ly α emitters and the Ly α escape fraction from z ∼ 2 to 6. Monthly Notices of the Royal Astronomical Society. 476(4), 4725–4752.","chicago":"Sobral, David, Sérgio Santos, Jorryt J Matthee, Ana Paulino-Afonso, Bruno Ribeiro, João Calhau, and Ali A Khostovan. “Slicing COSMOS with SC4K: The Evolution of Typical Ly α Emitters and the Ly α Escape Fraction from z ∼ 2 to 6.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2018. <a href=\"https://doi.org/10.1093/mnras/sty378\">https://doi.org/10.1093/mnras/sty378</a>."},"day":"01","_id":"11558","language":[{"iso":"eng"}],"abstract":[{"text":"We present and explore deep narrow- and medium-band data obtained with the Subaru and the Isaac Newton Telescopes in the ∼2 deg2 COSMOS field. We use these data as an extremely wide, low-resolution (R ∼ 20–80) Integral Field Unit survey to slice through the COSMOS field and obtain a large sample of ∼4000 Ly α emitters (LAEs) from z ∼ 2 to 6 in 16 redshift slices (SC4K). We present new Ly α luminosity functions (LFs) covering a comoving volume of ∼108 Mpc3. SC4K extensively complements ultradeep surveys, jointly covering over 4 dex in Ly α luminosity and revealing a global (2.5 < z < 6) synergy LF with α=−1.93+0.12−0.12⁠, log10Φ∗Lyα=−3.45+0.22−0.29 Mpc−3, and log10L∗Lyα=42.93+0.15−0.11 erg s−1. The Schechter component of the Ly α LF reveals a factor ∼5 rise in L∗Lyα and a ∼7 × decline in Φ∗Lyα from z ∼ 2 to 6. The data reveal an extra power-law (or Schechter) component above LLy α ≈ 1043.3 erg s−1 at z ∼ 2.2–3.5 and we show that it is partially driven by X-ray and radio active galactic nucleus (AGN), as their Ly α LF resembles the excess. The power-law component vanishes and/or is below our detection limits above z > 3.5, likely linked with the evolution of the AGN population. The Ly α luminosity density rises by a factor ∼2 from z ∼ 2 to 3 but is then found to be roughly constant (⁠1.1+0.2−0.2×1040 erg s−1 Mpc−3) to z ∼ 6, despite the ∼0.7 dex drop in ultraviolet (UV) luminosity density. The Ly α/UV luminosity density ratio rises from 4 ± 1 per cent to 30 ± 6 per cent from z ∼ 2.2 to 6. Our results imply a rise of a factor of ≈2 in the global ionization efficiency (ξion) and a factor ≈4 ± 1 in the Ly α escape fraction from z ∼ 2 to 6, hinting for evolution in both the typical burstiness/stellar populations and even more so in the typical interstellar medium conditions allowing Ly α photons to escape.","lang":"eng"}],"external_id":{"arxiv":["1712.04451"]},"type":"journal_article","quality_controlled":"1"},{"publication_status":"published","keyword":["Space and Planetary Science","Astronomy and Astrophysics","galaxies: evolution","galaxies: haloes","galaxies: high-redshift","galaxies: luminosity function","mass function","galaxies: statistics","cosmology: observations"],"publication_identifier":{"issn":["0035-8711"],"eissn":["1365-2966"]},"arxiv":1,"oa_version":"Preprint","title":"The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23","date_created":"2022-07-12T12:04:16Z","doi":"10.1093/mnras/stw3090","oa":1,"acknowledgement":"We thank the reviewer for his/her helpful comments and suggestions that have greatly improved this work. DS and JM acknowledge financial support from the Netherlands Organisation for Scientific research (NWO) through a Veni fellowship. DS also acknowledges funding from FCT through an FCT Investigator Starting Grant and Start-up Grant (IF/01154/2012/CP0189/CT0010). PNB is grateful for support from the UK STFC via grant ST/M001229/1. IRS acknowledges support from STFC (ST/L00075X/1), the ERC Advanced Investigator programme DUSTYGAL 321334 and a Royal Society/Wolfson merit award. We thank Matthew Hayes, Ryan Trainor, Kimihiko Nakajima and Anne Verhamme for many helpful discussions and Ana Sobral, Carolina Duarte and Miguel Domingos for taking part in observations with the NB392 filter. We also thank Sergio Santos for helpful comments. This research is based on observations obtained on the Isaac Newton Telescope (INT), programs: I13AN002, I14AN002, 088-INT7/14A, I14BN006, 118-INT13/14B & I15AN008. The authors acknowledge the award of time from programmes: I13AN002, I14AN002, 088-INT7/14A, I14BN006, 118-INT13/14B, I15AN008 on the INT. INT is 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 ESO Telescopes at the La Silla Paranal Observatory under programme ID 098.A 0819. We have benefited greatly from the publicly available programming language PYTHON, including the NUMPY, MATPLOTLIB, PYFITS, SCIPY and ASTROPY packages, the astronomical imaging tools SEXTRACTOR, SWARP (Bertin & Arnouts 1996; Bertin 2010), SCAMP (Bertin 2006) and TOPCAT (Taylor 2005). Dedicated to the memory of M. L. Nicolau and M. C. Serrano.","month":"04","article_type":"original","volume":466,"author":[{"first_name":"David","full_name":"Sobral, David","last_name":"Sobral"},{"first_name":"Jorryt J","id":"7439a258-f3c0-11ec-9501-9df22fe06720","orcid":"0000-0003-2871-127X","full_name":"Matthee, Jorryt J","last_name":"Matthee"},{"first_name":"Philip","last_name":"Best","full_name":"Best, Philip"},{"first_name":"Andra","last_name":"Stroe","full_name":"Stroe, Andra"},{"last_name":"Röttgering","full_name":"Röttgering, Huub","first_name":"Huub"},{"last_name":"Oteo","full_name":"Oteo, Iván","first_name":"Iván"},{"last_name":"Smail","full_name":"Smail, Ian","first_name":"Ian"},{"last_name":"Morabito","full_name":"Morabito, Leah","first_name":"Leah"},{"last_name":"Paulino-Afonso","full_name":"Paulino-Afonso, Ana","first_name":"Ana"}],"publisher":"Oxford University Press","article_processing_charge":"No","extern":"1","quality_controlled":"1","type":"journal_article","external_id":{"arxiv":["1609.05897"]},"_id":"11562","language":[{"iso":"eng"}],"abstract":[{"text":"We present the CAlibrating LYMan-α with Hα (CALYMHA) pilot survey and new results on Lyman α (Lyα) selected galaxies at z ∼ 2. We use a custom-built Lyα narrow-band filter at the Isaac Newton Telescope, designed to provide a matched volume coverage to the z = 2.23 Hα HiZELS survey. Here, we present the first results for the COSMOS and UDS fields. Our survey currently reaches a 3σ line flux limit of ∼4 × 10−17 erg s−1 cm−2, and a Lyα luminosity limit of ∼1042.3 erg s−1. We find 188 Lyα emitters over 7.3 × 105 Mpc3, but also find significant numbers of other line-emitting sources corresponding to He II, C III] and C IV emission lines. These sources are important contaminants, and we carefully remove them, unlike most previous studies. We find that the Lyα luminosity function at z = 2.23 is very well described by a Schechter function up to LLy α ≈ 1043 erg s−1 with L∗=1042.59+0.16−0.08 erg s−1, ϕ∗=10−3.09+0.14−0.34 Mpc−3 and α = −1.75 ± 0.25. Above LLy α ≈ 1043 erg s−1, the Lyα luminosity function becomes power-law like, driven by X-ray AGN. We find that Lyα-selected emitters have a high escape fraction of 37 ± 7 per cent, anticorrelated with Lyα luminosity and correlated with Lyα equivalent width. Lyα emitters have ubiquitous large (≈40 kpc) Lyα haloes, ∼2 times larger than their Hα extents. By directly comparing our Lyα and Hα luminosity functions, we find that the global/overall escape fraction of Lyα photons (within a 13 kpc radius) from the full population of star-forming galaxies is 5.1 ± 0.2 per cent at the peak of the star formation history. An extra 3.3 ± 0.3 per cent of Lyα photons likely still escape, but at larger radii.","lang":"eng"}],"day":"01","citation":{"apa":"Sobral, D., Matthee, J. J., Best, P., Stroe, A., Röttgering, H., Oteo, I., … Paulino-Afonso, A. (2017). The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23. <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href=\"https://doi.org/10.1093/mnras/stw3090\">https://doi.org/10.1093/mnras/stw3090</a>","mla":"Sobral, David, et al. “The CALYMHA Survey: Lyα Luminosity Function and Global Escape Fraction of Lyα Photons at z = 2.23.” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 466, no. 1, Oxford University Press, 2017, pp. 1242–58, doi:<a href=\"https://doi.org/10.1093/mnras/stw3090\">10.1093/mnras/stw3090</a>.","ieee":"D. Sobral <i>et al.</i>, “The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23,” <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 466, no. 1. Oxford University Press, pp. 1242–1258, 2017.","short":"D. Sobral, J.J. Matthee, P. Best, A. Stroe, H. Röttgering, I. Oteo, I. Smail, L. Morabito, A. Paulino-Afonso, Monthly Notices of the Royal Astronomical Society 466 (2017) 1242–1258.","chicago":"Sobral, David, Jorryt J Matthee, Philip Best, Andra Stroe, Huub Röttgering, Iván Oteo, Ian Smail, Leah Morabito, and Ana Paulino-Afonso. “The CALYMHA Survey: Lyα Luminosity Function and Global Escape Fraction of Lyα Photons at z = 2.23.” <i>Monthly Notices of the Royal Astronomical Society</i>. Oxford University Press, 2017. <a href=\"https://doi.org/10.1093/mnras/stw3090\">https://doi.org/10.1093/mnras/stw3090</a>.","ama":"Sobral D, Matthee JJ, Best P, et al. The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23. <i>Monthly Notices of the Royal Astronomical Society</i>. 2017;466(1):1242-1258. doi:<a href=\"https://doi.org/10.1093/mnras/stw3090\">10.1093/mnras/stw3090</a>","ista":"Sobral D, Matthee JJ, Best P, Stroe A, Röttgering H, Oteo I, Smail I, Morabito L, Paulino-Afonso A. 2017. The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23. Monthly Notices of the Royal Astronomical Society. 466(1), 1242–1258."},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","year":"2017","intvolume":"       466","main_file_link":[{"url":"https://arxiv.org/abs/1609.05897","open_access":"1"}],"date_published":"2017-04-01T00:00:00Z","publication":"Monthly Notices of the Royal Astronomical Society","date_updated":"2024-10-14T11:35:37Z","status":"public","page":"1242-1258","scopus_import":"1","issue":"1"}]