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Record 32 of 155
First Detection of a Foreground Damped Ly-Alpha Absorber Along a GRB Line of Sight?
Author and Affiliation:
Vreeswijk, P. M.(Amsterdam Univ., Astronomical Inst. 'Anton Pannekoek', Netherlands)
Fruchter, A. S.(Space Telescope Science Inst., Baltimore, MD United States)
Pian, E.(Consiglio Nazionale delle Ricerche, Bologna, Italy)
Rol, E.(Amsterdam Univ., Astronomical Inst. 'Anton Pannekoek', Netherlands)
Wijers, R. A. M. J.(State Univ. of New York, Dept. of Physics and Astronomy, Stony Brook, NY United States)
Kouveliotou, C.(NASA Marshall Space Flight Center, Huntsville, AL United States)
Kaper, L.(Amsterdam Univ., Astronomical Inst. 'Anton Pannekoek', Netherlands)
Palazzi, E.(Consiglio Nazionale delle Ricerche, Bologna, Italy)
Masetti, N.(Consiglio Nazionale delle Ricerche, Bologna, Italy)
Frontera, F.(Consiglio Nazionale delle Ricerche, Bologna, Italy) Show more authors
Abstract: We present a VLT spectrum of the optical afterglow of GRB 991216, taken 1.5 days after the burst, and HST (Hubble Space Telescope) imaging of the host galaxy, obtained four months later. The spectrum contains three metal absorption-line systems with redshifts z = 1.024, z = 0.803, and z = 0.771, where the highest redshift most likely reflects the distance to the host galaxy. For the z = 1.024 and z = 0.803 systems we tentatively detect MgI which suggests a dense environment at these redshifts. This and the strength of the z = 0.803 Fe lines indicate that this system very likely is a damped Ly-alpha absorber (DLA), which would be the first foreground DLA to be detected along a GRB afterglow sight line. The HST images are consistent with these findings: they show two blobs of light, one underneath the projected OT position, the presumed host galaxy, and the other 0.6" away, which is probably responsible for the absorption lines at z = 0.803. The lowest redshift system can be explained by either one of the two galaxies that are located roughly 2" away from the transient. Including these newly found systems, the total number of DLAS and Lyman limit systems along GRB afterglow sight lines is consistent with the number expected from QSO (quasi-stellar object) absorption line studies. We expect early spectroscopy of GRB afterglows to significantly increase the number of detected foreground absorption systems, and we discuss some advantages over QSO lines of sight.
Publication Date: Jan 01, 2001
Document ID:
20010039411
(Acquired May 14, 2001)
Subject Category: ASTRONOMY
Document Type: Preprint
Financial Sponsor: NASA Marshall Space Flight Center; Huntsville, AL United States
Organization Source: NASA Marshall Space Flight Center; Huntsville, AL United States
Description: 2p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: AFTERGLOWS; LINE OF SIGHT; RED SHIFT; QUASARS; HUBBLE SPACE TELESCOPE; SPECTRA; GALAXIES
Availability Source: Other Sources
Availability Notes: Abstract Only
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