2005/03/01 by Sebastián López, S. Lopez, D. Reimers +6 · 41 citations
Physics and Astronomy · #Abundance (ecology) #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Galaxies: Formation, Evolution, Phenomena #Galaxy #Hubble space telescope #Line (geometry) #Line-of-sight #Physics #Redshift #Space Telescope Imaging Spectrograph #Spectral line #Spectral resolution #Spectrograph #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/429956
published in The Astrophysical Journal 626(2), 767-775 (IOP Publishing) · In press at ApJ
arxiv created 2005/03/01 · openalex publication_date 2005/06/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study metal abundances in the z = 0.9313 damped Lyα system observed along the two lines of sight, A and B, toward the gravitationally lensed double QSO HE 0512-3329. Spatially resolved Space Telescope Imaging Spectrograph spectra constrain the neutral-gas column density to be N (H ) = 10 20.5 cm -2 in both A and B. UV-visual Echelle Spectrograph spectra (spectral resolution FWHM = 9.8 km s -1 ) show, in contrast, significant line-of-sight differences in the column densities of Mn II and Fe II; these are not due to observational systematics. We find that [Mn/H] = -1.44 and [Fe/H] = -1.52 in damped Lyα system A, while [Mn/H] = -0.98 and [Fe/H] > -1.32, and possibly as high as [Fe/H] ≈ -1, in damped Lyα system B. A careful assessment of possible systematic errors leads us to conclude that these transverse differences are significant at a 5 σ level or greater. Although nucleosynthesis effects may also be at play, we favor differential dust depletion as the main mechanism producing the observed abundance gradient. The transverse separation is 5 h kpc at the redshift of the absorber, which is also likely to be the lensing galaxy. The derived abundances therefore probe two opposite sides of a single galaxy hosting both damped Lyα systems. This is the first time firm abundance constraints have been obtained for a single damped system probed by two lines of sight. The significance of this finding for the cosmic evolution of metals is discussed.