{"paper":{"title":"Chandra Detection of OVIII Ly-alpha Absorption from an Overdense Region in the Intergalactic Medium","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"C. R. Canizares (MIT), D. S. Davis, H. L. Marshall, J. C. Lee, T. Fang","submitted_at":"2002-06-16T19:04:05Z","abstract_excerpt":"We report the first detection of an OVIII Ly-alpha absorption line associated with an overdense region in the intergalactic medium (IGM) along the sightline towards PKS 2155-304 with the Chandra Low Energy Transmission Grating Spectrometer (LETGS). The absorption line is detected at 4.5 sigma level with cz~16,600 km/s. At the same velocity Shull et al.(1998) detected a small group of spiral galaxies (with an overdensity of delta_gal ~ 100) and low metallicity HI Ly-alpha clouds. We constrain the intragroup gas that gives rise to the OVIII Ly-alpha line to a baryon density in the range 1e-5 < n"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0206264","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"}