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OATS-DAUT SEMINAR
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Speaker: Matteo Viel (INAF/Oss. Astron. di Trieste)

Title: Strong MgII systems in quasar and gamma-ray burst spectra

Date: Wednesday, November 8th, 2006
Time: 12:00 noon
Venue: Villa Bazzoni

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Abstract:
Strong MgII absorption (with equivalent width W>0.3 Angstrom) is produced in patchy gaseous envelopes, up to impact parameters of 80 kpc/h, surrounding galaxies of different morphological types. The incidence of these systems in gamma-ray bursts (GRB) and BL Lac spectra is a few times higher than in quasar (QSO) spectra. I investigate several possible explanations for this effect including: dust obscuration bias, clustering of the absorbers, different beam sizes of the sources, magnification bias of GRBs (i.e. microlensing events), association of the absorbers with the GRB event or the circumburst environment.
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