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N.A. Bond, C.W. Churchill, J.C. Charlton (Penn State)
We present high-resolution profiles of four extremely strong (Wr > 1.8 Å) Mg II absorbers at 1 < z < 2. The profiles display a common kinematic structure, having a sharp drop in optical depth near the center of the profile and strong absorption on either side. This symmetric double-structure, with a velocity spread of several hundred km/s, is suggestive of superwinds arising in actively star-forming galaxies. Low-ionization absorption of similar strength has been observed in local star-forming galaxies (e.g. Heckman et al. 2000). Norman et al. (1996) see absorption out to ~20 kpc.
Mg II absorbers with Wr > 1 Åevolve away from z = 2 to the present. We propose that a large fraction of these absorbers are due to superwinds and that their evolution is related to the evolution of star-forming galaxies over that redshift interval. Based on the observed number density of Wr > 1.8 ÅMg II absorbers per unit redshift (Steidel and Sargent 1992), we explore whether it is realistic that superwinds in the star-forming population at 1 < z < 2 could give rise to these absorbers.
The author(s) of this abstract have provided an email address for comments about the abstract: bond@astro.psu.edu