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Published March 4, 2004 | Published
Journal Article Open

ISAAC/VLT observations of a lensed galaxy at z = 10.0

Abstract

We report the first likely spectroscopic confirmation of a z ~ 10.0 galaxy from our ongoing search for distant galaxies with ISAAC/VLT. Galaxy candidates at z ≳ 7 are selected from ultra-deep JHKs images in the core of gravitational lensing clusters for which deep optical imaging is also available, including HST data. The object reported here, found behind Abell 1835, exhibits a faint emission line detected in the J band, leading to z = 10.0 when identified as Lyα, in excellent agreement with the photometric redshift determination. Redshifts z 〈 7 are very unlikely for various reasons we discuss. The object is located on the critical lines corresponding to z = 9 to 11. The magnification factor μ ranges from 25 to 100. For this object we estimate SFR(Lyα) ~ (0.8-2.2) M_⊙ yr^(-1) and SFR(UV) ~ (47-75) M_⊙ yr^(-1), both uncorrected for lensing. The steep UV slope indicates a young object with negligible dust extinction. SED fits with young low-metallicity stellar population models yield (adopting µ = 25) a lensing corrected stellar mass of M_★ ~ 8 x 10^6 M_⊙, and luminosities of 2 x 10^(10) L_⊙, corresponding to a dark matter halo of a mass of typically M_(tot) ≳ 5 x 10^8 M_⊙ . In general our observations show that under excellent conditions and using strong gravitational lensing direct observations of galaxies close to the "dark ages" are feasible with ground-based 8-10 m class telescopes.

Additional Information

© 2004 ESO. Received: 20 January 2004. Accepted: 13 February 2004. We are grateful to R. Behrend, B. Ciardi, T. Contini, A. Ferrara, Y. Izotov, M. Lemoine-Busserolle, D. Pfenniger, D. Valls-Gabaud, S. White and various other colleagues for useful comments and discussions. C. Charbonnel, G. Schaerer also contributed indirectly to the finalisation of this work. We thank the ESO Director General for a generous allocation of Director's Discretionary Time for ISAAC spectroscopy (DDT 271.A-5013). Also based on observations collected at the European Southern Observatory, Chile (70.A-0355), the NASA/ESA Hubble Space Telescope operated by the Association of Universities for Research in Astronomy, Inc., and the Canada-France-Hawaii Telescope operated by the National Research Council of Canada, the French Centre National de la Recherche Scientifique (CNRS) and the University of Hawaii. Part of this work was supported by the CNRS and the Swiss National Foundation. J.P.K. acknowledges support from Caltech and the CNRS.

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August 19, 2023
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October 18, 2023