http://arxiv.org/abs/1707.07697
GRB 020903 is a long-duration gamma ray burst (LGRB) with a host galaxy close enough and extended enough for spatially-resolved observations, making it one of less than a dozen GRBs where such host studies are possible. GRB 020903 lies in a galaxy host complex that appears to consist of four interacting components. Here we present the results of spatially-resolved spectroscopic observations of the GRB 020903 host. By taking observations at two different position angles we were able to obtain optical spectra (3600-9000{\AA}) of multiple regions in the host complex. After examining the data we conclude that the GRB 020903 host is not, as previously believed, composed of four interacting regions – two are star-forming regions at the same redshift as the GRB explosion site (z=0.251), while two others appear to comprise a background star-forming galaxy at z=0.662. We also measure the metallicities of the two regions at the redshift of GRB 020903, and find that the explosion site and the nearby star-forming region both have metallicities of log(O/H)+12 ~ 8.1 +/- 0.2. We conclude that, in agreement with past spatially-resolved studies of GRBs, the GRB explosion site is representative of the host galaxy as a whole rather than localized in a metal-poor region of the galaxy.
M. Thorp and E. Levesque
Wed, 26 Jul 17
18/68
Comments: 6 pages, 4 figures, to be submitted to AJ