A spatially resolved map of the kinematics, star formation and stellar mass assembly in a star-forming galaxy at z = 4.9 - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2009

A spatially resolved map of the kinematics, star formation and stellar mass assembly in a star-forming galaxy at z = 4.9

Résumé

We present a detailed study of the spatially resolved kinematics, star formation and stellar mass in a highly amplified galaxy at z = 4.92 behind the lensing cluster MS1358+62. We use the observed optical, near- and mid-infrared imaging from Hubble Space Telescope ACS & NICMOS and Spitzer IRAC to derive the stellar mass and the Gemini/NIFS IFU to investigate the velocity structure of the galaxy from the nebular [OII]λλ3726.8,3728.9 emission. Using a detailed gravitational lens model, we account for lensing amplification factor 12.5 +/- 2.0 and find that this intrinsically L* galaxy has a stellar mass of M* = 7 +/- 2 × 108Msolar, a dynamical mass of Mdyn = 3 +/- 1 × 109csc2(i)Msolar (within of 2kpc) and a star formation rate of 42 +/- 8Msolaryr-1. The source-plane UV/optical morphology of this galaxy is dominated by five discrete star-forming regions. Exploiting the dynamical information we derive masses for individual star-forming regions of Mcl ~ 108-9Msolar with sizes of ~200pc. We find that, at a fixed size, the star formation rate density within these HII regions is approximately two orders of magnitude greater than those observed in local spiral/starburst galaxies, but consistent with the most massive HII regions in the local Universe such as 30Doradus. Finally, we compare the spatially resolved nebular emission-line velocity with the Lyα and UV interstellar medium (ISM) lines and find that this galaxy is surrounded by a galactic scale outflow in which the Lyα appears redshifted by ~150kms-1 and the UV-ISM lines blueshifted by ~ -200kms-1 from the (systemic) nebular emission. The velocity structure of the outflow mirrors that of the nebular emission suggesting the outflow is young (<~15Myr), and has yet to burst out of the system. Taken together, these results suggest that this young galaxy is undergoing its first major epoch of mass assembly.

Dates et versions

hal-00660852 , version 1 (17-01-2012)

Identifiants

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A. M. Swinbank, T. M. Webb, J. Richard, R. G. Bower, R. S. Ellis, et al.. A spatially resolved map of the kinematics, star formation and stellar mass assembly in a star-forming galaxy at z = 4.9. Monthly Notices of the Royal Astronomical Society, 2009, 400, pp.1121-1131. ⟨10.1111/J.1365-2966.2009.15617.X⟩. ⟨hal-00660852⟩
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