Journal Article

Medium-resolution spectroscopy of FORJ0332−3557: probing the interstellar medium and stellar populations of a lensed Lyman-break galaxy at <i>z</i>= 3.77*

Rémi A. Cabanac, David Valls-Gabaud and Chris Lidman

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 386, issue 4, pages 2065-2074
Published in print June 2008 | ISSN: 0035-8711
Published online April 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13157.x
Medium-resolution spectroscopy of FORJ0332−3557: probing the interstellar medium and stellar populations of a lensed Lyman-break galaxy at z= 3.77*

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We recently reported the discovery of FORJ0332−3557, a lensed Lyman-break galaxy at z= 3.77 in a remarkable example of strong galaxy–galaxy gravitational lensing. We present here a medium-resolution rest-frame ultraviolet (UV) spectrum of the source, which appears to be similar to the well-known Lyman-break galaxy MS1512−cB58 at z= 2.73. The spectral energy distribution is consistent with a stellar population of less than 30 Ma, with an extinction of Av= 0.5 mag and an extinction-corrected star formation rate SFRUV of 200–300 h−170 M a−1. The Lyα line exhibits a damped profile in absorption produced by a column density of about NH i= (2.5 ± 1.0) × 1021cm−2, superimposed on an emission line shifted both spatially (0.5 arcsec with respect to the UV continuum source) and in velocity space (+830 km s−1 with respect to the low-ionization absorption lines from its interstellar medium), a clear signature of outflows with an expansion velocity of about 270 km s−1. A strong emission line from He iiλ164.04 nm indicates the presence of Wolf–Rayet stars and reinforces the interpretation of a very young starburst. The metallic lines indicate subsolar abundances of elements Si, Al and C in the ionized gas phase.

Keywords: gravitational lensing; galaxies: abundances; galaxies: evolution; galaxies: high-redshift; galaxies: ISM; galaxies: starburst; galaxies: stellar content

Journal Article.  6076 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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