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Article Dans Une Revue The Astrophysical Journal Année : 2007

A Detailed Study of Gas and Star Formation in a Highly Magnified Lyman Break Galaxy at z = 3.07

K. E. K. Coppin
  • Fonction : Auteur
A. M. Swinbank
  • Fonction : Auteur
R. Neri
P. Cox
Ian Smail
J. E. Geach
  • Fonction : Auteur
B. Siana
  • Fonction : Auteur
H. Teplitz
S. Dye
  • Fonction : Auteur
A. C. Edge
  • Fonction : Auteur

Résumé

We report the detection of CO(3-2) emission from a bright, gravitationally lensed Lyman Break galaxy, LBG J213512.73-010143 (the ``Cosmic Eye''), at z=3.07, using the Plateau de Bure Interferometer. This is only the second detection of molecular gas emission from an LBG and yields an intrinsic molecular gas mass of (2.4+/-0.4)×109 Msolar. The lens reconstruction of the UV morphology of the LBG indicates that it comprises two components separated by ~2 kpc. The CO emission is unresolved, ?<~3'', and appears to be centered on the intrinsically fainter (and also less highly magnified) of the two UV components. The width of the CO line indicates a dynamical mass of (8+/-2)×109csc2i Msolar within the central 2 kpc. Employing mid-infrared observations from Spitzer, we infer a stellar mass of M*~(6+/-2)×109 Msolar and a star formation rate of ~60 Msolar yr-1, indicating that the molecular gas will be consumed in <~40 Myr. The gas fractions, star formation efficiencies, and line widths suggests that LBG J213512 is a high-redshift, gas-rich analog of a local luminous infrared galaxy. This galaxy has a similar gas-to-dynamical mass fraction as observed in the submillimeter-selected population, although the gas surface density and star formation efficiency is a factor of 3 times less, suggesting less vigorous activity. We discuss the uncertainties in our conclusions arising from adopting a CO-to-H2 conversion factor appropriate for either the Milky Way or local luminous infrared galaxies. These observations demonstrate that current facilities, when aided by fortuitous gravitational magnification, can study ``ordinary'' galaxies at high redshift and so act as pathfinders for ALMA.

Dates et versions

hal-00193519 , version 1 (03-12-2007)

Identifiants

Citer

K. E. K. Coppin, A. M. Swinbank, R. Neri, P. Cox, Ian Smail, et al.. A Detailed Study of Gas and Star Formation in a Highly Magnified Lyman Break Galaxy at z = 3.07. The Astrophysical Journal, 2007, 665, pp.936-943. ⟨10.1086/519789⟩. ⟨hal-00193519⟩
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