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Physical properties of two low-luminosity z ~ 1.9 galaxies behind the lensing cluster AC 114

Lemoine-Busserolle, M. and Contini, T. and Pelló, R. and Le Borgne, J.-F. and Kneib, J.-P. and Lidman, C. (2003) Physical properties of two low-luminosity z ~ 1.9 galaxies behind the lensing cluster AC 114. Astronomy & Astrophysics, 397 (3). pp. 839-849. ISSN 0004-6361. doi:10.1051/0004-6361:20021564.

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We present VLT/ISAAC near-infrared spectroscopy of two gravitationally-lensed z ~ 1.9 galaxies, A2 and S2, located behind the cluster AC 114. Thanks to large magnification factors, we have been successful in detecting rest-frame optical emission lines (from [O ii]λ3727 to Hα +[N ii]λ6584) in star-forming galaxies 1 to 2 mag fainter than in previous studies of Lyman break galaxies (LBGs) at z ~ 3. From the Hα luminosity, we estimate star formation rates (SFRs) of 30 and 15 M_⊙ yr^(-1) for S2 and A2 respectively. These values are 7 to 15 times higher than those inferred from the UV continuum flux at 1500 Å without dust extinction correction. In setting SFR_(Hα) ~ SFR_(UV), one derives extinction coefficients E(B - V) ~ 0.3 for S2 and E(B - V) ~ 0.4 for A2. The behavior of S2 and A2 in terms of O/H and N/O abundance ratios are very different, and they are also different from typical LBGs at z ~ 3. S2 is a low-metallicity object (Z ~ 0.03^(Z_⊙)) with a low N/O ratio, similar to those derived in the most metal-poor nearby Hiigalaxies. In contrast, A2 is a high-metallicity galaxy (Z ~ 1.3^(Z_⊙)) with a high N/O abundance ratio, similar to those derived in the most metal-rich starburst nucleus galaxies. The line-of-sight velocity dispersions, derived from emission line widths, are 55 and 105 km s^(-1), yielding a virial mass of 0.5 and 2.4 x 10^(10) M_⊙, for S2 and A2 respectively. Thanks to the gravitational amplification, the line profiles of S2 are spatially resolved, leading to a velocity gradient of ±240 km s^(-1), which yields a dynamical mass of ~ 1.3 x 10^(10) M_⊙ within the inner 1 kpc radius. Combining these new data with the sample of LBGs at z ~ 3, including the lensed galaxy MS 1512-cB58, which is the only LBG for which physical properties have been determined with similar accuracy, we conclude that these three galaxies exhibit different physical properties in terms of abundance ratios, SFRs, M/L_B and reddening. High-redshift galaxies of different luminosities could thus have quite different star formation histories.

Item Type:Article
Related URLs:
URLURL TypeDescription
Kneib, J.-P.0000-0002-4616-4989
Lidman, C.0000-0003-1731-0497
Additional Information:© 2003 ESO.. Received: 4 September 2002. Accepted: 22 October 2002. We are grateful to G. Bruzual, F. Courbin, G. Golse, H. A. Kobulnicky, M. Pettini, D. Schaerer, J. Richard and J. Gallego for useful discussions on this particular program. Part of this work was supported by the French Conseil Régional de la Martinique, by the French Centre National de la Recherche Scientifique, the TMR Lensnet ERBFMRXCT97-0172 ( and the ECOS SUD Program (ECOS/CONICYT CU00U05).
Funding AgencyGrant Number
Conseil Régional de la MartiniqueUNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
TMR LensnetERBFMRXCT97-0172
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)UNSPECIFIED
Subject Keywords:galaxies: evolution - galaxies: starburst - galaxies: abundances - galaxies: kinematics and dynamics - infrared: galaxies
Issue or Number:3
Record Number:CaltechAUTHORS:20180228-102143884
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Official Citation:Physical properties of two low-luminosity Formula galaxies behind the lensing cluster AC 114 M. Lemoine-Busserolle, T. Contini, R. Pelló, J.-F. Le Borgne, J.-P. Kneib and C. Lidman A&A, 397 3 (2003) 839-849 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85005
Deposited By: Ruth Sustaita
Deposited On:28 Feb 2018 20:07
Last Modified:15 Nov 2021 20:24

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