Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-02-27
Astron.J.131:2755-2762,2006
Astronomy and Astrophysics
Astrophysics
Astron J., in press (June 2006)
Scientific paper
10.1086/503705
FUSE spectra of star-forming regions in nearby galaxies are compared to composite spectra of Lyman-break galaxies (LBGs), binned by strength of Lyman alpha emission and by mid-UV luminosity. Several far-UV spectral features, including lines dominated by stellar wind and by photospheric components, are very sensitive to stellar abundances. Their measurement in Lyman-break galaxies is compromised by the strong interstellar absorption features, allowing in some cases only upper limits. The derived C and N abundances in the LBGs are no higher than half solar (scaled to oxygen abundance for comparison with emission-line analyses), independent of the strength of Lyman alpha emission. P V absorption indicates abundances as low as 0.1 solar, with an upper limit near 0.4 solar in the reddest and weakest-emission galaxies. Unresolved interstellar absorption components would further lower the derived abundances. Trends of line strength, and derived abundances, are stronger with mid-UV luminosity than with Lyman-alpha strength. H2 absorption in the Lyman and Werner bands is very weak in the LBGs. Template H2 absorption spectra convolved to appropriate resolution show that strict upper limits N(H2)< 10^18 cm^-2 apply in all cases, with more stringent values appropriate for the stronger-emission composites and for mixes of H2 level populations like those on Milky Way sight lines. Since the UV-bright regions are likely to be widespread in these galaxies, these results rule out massive diffuse reservoirs of H2, and suggest that the dust/gas ratio is already fairly large at z~3.
No associations
LandOfFree
Stellar abundances and molecular hydrogen in high-redshift galaxies -the far-ultraviolet view does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Stellar abundances and molecular hydrogen in high-redshift galaxies -the far-ultraviolet view, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stellar abundances and molecular hydrogen in high-redshift galaxies -the far-ultraviolet view will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-387561