{"paper":{"title":"A deep ROSAT Survey - XII. The X-ray spectra of faint ROSAT sources","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"Brian J. Boyle, Gordon C. Stewart, Ioannis Georgantopoulos, Nathan Roche, Omar Almaini, Richard E. Griffiths, Tom Shanks","submitted_at":"1996-05-17T16:14:02Z","abstract_excerpt":"Optical spectroscopy has enabled us to identify the optical counterparts to over 200 faint X-ray sources to a flux limit of S_(0.5-2keV)=4x10^-15 erg s^-1 cm^-2 on 5 deep ROSAT fields. Here we present a spectral analysis of all the X-ray sources to investigate claims that the average source spectra harden at faint X-ray flux. From a hardness ratio analysis we confirm that the average spectra from 0.5-2 keV harden from an equivalent photon index of $\\Gamma=2.2$ at S_(0.5-2keV)=1x10^-13 erg s^-1 cm^-2 to $\\Gamma=1.7$ below 1x10^-14 erg s^-1 cm^-2. These spectral changes are due to the emergence "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/9605106","kind":"arxiv","version":2},"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"}