{"paper":{"title":"Dramatic X-ray spectral variability of a Compton-thick type-1 QSO at $z\\sim 1$","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.HE"],"primary_cat":"astro-ph.GA","authors_text":"(2) Pontificia Universidad Catolica de Chile, 3), (3) Excellence Cluster Universe, (4) Department of Astronomy, (5) Argelander-Institut f\\\"ur Astronomie, (6) Center for Astrophysics, (7) Steward Observatory, (8) Department of Astronomy, 9) ((1) Max Planck Institute for Extraterrestrial Physics, (9) Institute for Gravitation, Alison L. Coil (6), Andrea Merloni (1), Astrophysics, Bonn, Chile, Christopher N. A. Willmer (7), Donald P. Schneider (8, Dpt. of Physics, Garching, Germany, Instituto de Astrofisica, Johannes Buchner (2, Kirpal Nandra (1), Santiago, Space Sciences, the Cosmos, The Pennsylvania State University, Thomas Erben (5), Torben Simm (1), Tucson, University of Arizona, University of Illinois at Urbana-Champaign, Univ. of California San Diego, USA, USA), Yue Shen (4)","submitted_at":"2018-08-15T17:56:39Z","abstract_excerpt":"We report on the discovery of a dramatic X-ray spectral variability event observed in a $z\\sim 1$ broad line type-1 QSO. The XMM-Newton spectrum from the year 2000 is characterized by an unobscured power-law spectrum with photon index of $\\Gamma\\sim 2$, a column density of $N_{\\mathrm{H}}\\sim 5\\times 10^{20}\\,\\mathrm{cm^{-2}}$, and no prominent reflection component. Five years later, Chandra captured the source in a heavily-obscured, reflection-dominated state. The observed X-ray spectral variability could be caused by a Compton-thick cloud with $N_{\\mathrm{H}}\\sim 2\\times 10^{24}\\,\\mathrm{cm^"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1808.05207","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"}