Identification of the brightest Lyα emitters at z = 6.6: implications for the evolution of the luminosity function in the reionization era
Matthee JJ, Sobral D, Santos S, Röttgering H, Darvish B, Mobasher B. 2015. Identification of the brightest Lyα emitters at z = 6.6: implications for the evolution of the luminosity function in the reionization era. Monthly Notices of the Royal Astronomical Society. 451(1), 400–417.
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Author
Matthee, Jorryt JISTA 
;
Sobral, David;
Santos, Sérgio;
Röttgering, Huub;
Darvish, Behnam;
Mobasher, Bahram
;
Sobral, David;
Santos, Sérgio;
Röttgering, Huub;
Darvish, Behnam;
Mobasher, BahramAbstract
Using wide-field narrow-band surveys, we provide a new measurement of the z = 6.6 Lymanα emitter (LAE) luminosity function (LF), which constraints the bright end for the first time. We use a combination of archival narrow-band NB921 data in UDS and new NB921 measurements in SA22 and COSMOS/UltraVISTA, all observed with the Subaru telescope, with a total area of ∼5 deg2. We exclude lower redshift interlopers by using broad-band optical and near-infrared photometry and also exclude three supernovae with data split over multiple epochs. Combining the UDS and COSMOS samples, we find no evolution of the bright end of the Lyα LF between z = 5.7 and 6.6, which is supported by spectroscopic follow-up, and conclude that sources with Himiko-like luminosity are not as rare as previously thought, with number densities of ∼1.5 × 10−5 Mpc−3. Combined with our wide-field SA22 measurements, our results indicate a non-Schechter-like bright end of the LF at z = 6.6 and a different evolution of observed faint and bright LAEs, overcoming cosmic variance. This differential evolution is also seen in the spectroscopic follow-up of UV-selected galaxies and is now also confirmed for LAEs, and we argue that it may be an effect of reionization. Using a toy model, we show that such differential evolution of the LF is expected, since brighter sources are able to ionize their surroundings earlier, such that Lyα photons are able to escape. Our targets are excellent candidates for detailed follow-up studies and provide the possibility to give a unique view on the earliest stages in the formation of galaxies and reionization process.
Publishing Year
Date Published
2015-07-21
Journal Title
Monthly Notices of the Royal Astronomical Society
Acknowledgement
We thank the anonymous referee for the comments and suggestions which have improved the quality of this work. We thank Masami Ouchi for his useful comments on an earlier version of this paper. JM acknowledges the support of a Huygens PhD fellowship from Leiden University and is thankful for the hospitality of the Center for Astronomy and Astrophysics of the University of Lisbon where part of this research has been done. DS acknowledges financial support from the Netherlands Organization for Scientific research (NWO) through a Veni fellowship, from FCT through a FCT Investigator Starting Grant and Start-up Grant (IF/01154/2012/CP0189/CT0010) and from FCT grant PEstOE/FIS/UI2751/2014. HR acknowledges support from the ERC Advanced Investigator programme NewClusters 321271. We acknowledge the award of ESO DDT time (294.A-5018) for providing the possibility of a timely publication of this work.
Based on observations with the Subaru Telescope (Programme IDs: our observations: S14A-086; archival: S05B-027, S06A-025, S06B-010, S07A-013, S07B-008, S08B-008 and S09A-017) and the W.M. Keck Observatory. The Subaru telescope is operated by the National Astronomical Observatory of Japan. The W.M. Keck Observatory is operated as a scientific partnership among 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 ID 294.A-5018. Based on observations obtained with MegaPrime/Megacam, a joint project of CFHT and CEA/IRFU, at the Canada–France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at Terapix available at the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS. 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 TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium.
In addition to the CFHT-LS and COSMOS-UltraVISTA surveys, we are grateful for the excellent data sets from the UKIRT-DXS, SXDF and S-COSMOS survey teams, without these legacy surveys, this research would have been impossible. We have benefited greatly 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 indispensable TOPCAT analysis tool (Taylor 2013)
Volume
451
Issue
1
Page
400-417
ISSN
eISSN
IST-REx-ID
Cite this
Matthee JJ, Sobral D, Santos S, Röttgering H, Darvish B, Mobasher B. Identification of the brightest Lyα emitters at z = 6.6: implications for the evolution of the luminosity function in the reionization era. Monthly Notices of the Royal Astronomical Society. 2015;451(1):400-417. doi:10.1093/mnras/stv947
Matthee, J. J., Sobral, D., Santos, S., Röttgering, H., Darvish, B., & Mobasher, B. (2015). Identification of the brightest Lyα emitters at z = 6.6: implications for the evolution of the luminosity function in the reionization era. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/stv947
Matthee, Jorryt J, David Sobral, Sérgio Santos, Huub Röttgering, Behnam Darvish, and Bahram Mobasher. “Identification of the Brightest Lyα Emitters at z = 6.6: Implications for the Evolution of the Luminosity Function in the Reionization Era.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2015. https://doi.org/10.1093/mnras/stv947.
J. J. Matthee, D. Sobral, S. Santos, H. Röttgering, B. Darvish, and B. Mobasher, “Identification of the brightest Lyα emitters at z = 6.6: implications for the evolution of the luminosity function in the reionization era,” Monthly Notices of the Royal Astronomical Society, vol. 451, no. 1. Oxford University Press, pp. 400–417, 2015.
Matthee JJ, Sobral D, Santos S, Röttgering H, Darvish B, Mobasher B. 2015. Identification of the brightest Lyα emitters at z = 6.6: implications for the evolution of the luminosity function in the reionization era. Monthly Notices of the Royal Astronomical Society. 451(1), 400–417.
Matthee, Jorryt J., et al. “Identification of the Brightest Lyα Emitters at z = 6.6: Implications for the Evolution of the Luminosity Function in the Reionization Era.” Monthly Notices of the Royal Astronomical Society, vol. 451, no. 1, Oxford University Press, 2015, pp. 400–17, doi:10.1093/mnras/stv947.
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