Massive Star Formation in a Gravitationally Lensed H II Galaxy at z = 3.357
Publication date: 21 October 2003
Authors: Fosbury, R.A.E., et al.
Journal: Astrophysical Journal
Volume: 596
Issue: 2
Page: 797-809
Year: 2003
Copyright: The American Astronomical Society
The Lynx arc, with a redshift of 3.357, was discovered during spectroscopic follow-up of the z=0.570 cluster RX J0848+4456 from the ROSAT Deep Cluster Survey. The arc is characterized by a very red R-K color and strong, narrow emission lines. Analysis of HST WFPC2 imaging and Keck optical and infrared spectroscopy shows that the arc is an H II galaxy magnified by a factor of ~10 by a complex cluster environment. The high intrinsic luminosity, the emission-line spectrum, the absorption components seen in Lyalpha and C IV, and the rest-frame ultraviolet continuum are all consistent with a simple H II region model containing ~106 hot O stars. The best-fit parameters for this model imply a very hot ionizing continuum (TBB~= 80 000 K), a high ionization parameter (logU~=-1), and a low nebular metallicity (Z/Zsolar~=0.05). The narrowness of the emission lines requires a low mass-to-light ratio for the ionizing stars, suggestive of an extremely low metallicity stellar cluster. The apparent overabundance of silicon in the nebula could indicate enrichment by past pair-instability supernovae, requiring stars more massive than ~140 Msolar.
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