{"paper":{"title":"A Compton-thick AGN at z~5 in the 4 Ms Chandra Deep Field South","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"A. Comastri, A. Fontana, A. Ptak, B. Luo, C. Norman, C. Vignali, F. Fiore, J. Su, M. Castellano, M. Stiavelli, P. Rosati, P. Tozzi, R. Gilli, V. Mainieri, W.N. Brandt, Y.Q. Xue","submitted_at":"2011-02-23T11:23:19Z","abstract_excerpt":"We report the discovery of a Compton-thick Active Galactic Nucleus (AGN) at z=4.76 in the 4 Ms Chandra Deep Field South. This object was selected as a V-band dropout in HST/ACS images and previously recognized as an AGN from optical spectroscopy. The 4 Ms Chandra observations show a significant (~4.2sigma) X-ray detection at the V-band dropout position. The X-ray source displays a hardness ratio of HR=0.23+-0.24, which, for a source at z~5, is highly suggestive of Compton-thick absorption. The source X-ray spectrum is seen above the background level in the energy range of ~0.9-4 keV, i.e., in "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1102.4714","kind":"arxiv","version":1},"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"}