{"paper":{"title":"A log N(HI) = 22.6 DLA in a dark gamma-ray burst: the environment of GRB 050401","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"(2) ESO, A. C. Andersen (1), A. Levan, A. P. Beardmore, A. Pozanenko, A. Smette (2), B. L. Jensen, Chile), C. Ledoux (2), Copenhagen, D. Bersier, D. Diaz-Fraile, D. Sharapov, D. Watson (1), G. Kosugi, J. Gorosabel, J. Hjorth (1), J. Masegosa, J. M. Castro Cer\\'on, J. N\\\"ar\\\"anen, J. N. Reeves, J. P. U. Fynbo (1), J. Sollerman, K. Aoki, K. L. Page, K. Pedersen, K. Torstensson, K. Wiersema ((1) DARK, N. Kawai, N. Tanvir, P. D'Avanzo, P. Hirst, P. Jakobsson, P. Laursen, P. Vreeswijk (2), R. L. C. Starling, T. Augusteijn, T. Shahbaz, V. Rumyantsev","submitted_at":"2005-10-12T20:01:50Z","abstract_excerpt":"The optical afterglow spectrum of GRB050401 (at z=2.8992+/-0.0004) shows the presence of a DLA, with log(nHI)=22.6+/-0.3. This is the highest column density ever observed in a DLA, and is about five times larger than the strongest DLA detected so far in any QSO spectrum. From the optical spectrum, we also find a very large Zn column density, allowing us to infer an abundance of [Zn/H]=-1.0+/-0.4. These large columns are supported by the X-ray spectrum from Swift-XRT which shows a column density (in excess of Galactic) of log(nH)=22.21^{+0.06}_{-0.08} assuming solar abundances (at z=2.9). The c"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0510368","kind":"arxiv","version":4},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}