{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2018:F4MRMLAUAD5V3S6NXVYWBGYYHJ","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"adb48d2390f9baae2254100109877c2ca6ad53c59491c33961cacf684d2c4a42","cross_cats_sorted":["astro-ph.CO"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2018-08-15T18:37:10Z","title_canon_sha256":"4ac6016f775248648e35a318b0271bcb42ffb8423e6ac64b73a8dc5e6248dc33"},"schema_version":"1.0","source":{"id":"1808.05247","kind":"arxiv","version":2}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1808.05247","created_at":"2026-05-17T23:47:20Z"},{"alias_kind":"arxiv_version","alias_value":"1808.05247v2","created_at":"2026-05-17T23:47:20Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1808.05247","created_at":"2026-05-17T23:47:20Z"},{"alias_kind":"pith_short_12","alias_value":"F4MRMLAUAD5V","created_at":"2026-05-18T12:32:22Z"},{"alias_kind":"pith_short_16","alias_value":"F4MRMLAUAD5V3S6N","created_at":"2026-05-18T12:32:22Z"},{"alias_kind":"pith_short_8","alias_value":"F4MRMLAU","created_at":"2026-05-18T12:32:22Z"}],"graph_snapshots":[{"event_id":"sha256:9f88f4206d22a2f8d7403e1b02fc8f3b70a6976c7e9b0ad3ccb0facf20915eb0","target":"graph","created_at":"2026-05-17T23:47:20Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"paper":{"abstract_excerpt":"We present measurements of the large-scale (~40 comoving Mpc) effective optical depth of HeII Ly$\\alpha$ absorption, $\\tau_{\\rm eff}$, at 2.54<z<3.86 toward 16 HeII-transparent quasars observed with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), to characterize the ionization state of helium in the intergalactic medium (IGM). We provide the first statistical sample of $\\tau_{\\rm eff}$ measurements in six signal-to-noise ratio >3 HeII sightlines at z>3.5, and study the redshift evolution and sightline-to-sightline variance of $\\tau_{\\rm eff}$ in 24 HeII sightlines. W","authors_text":"Frederick B. Davies (University of California Santa Barbara), G\\'abor Worseck (Universit\\\"at Potsdam), Joseph F. Hennawi (University of California Santa Barbara), J. Xavier Prochaska (University of California Santa Cruz)","cross_cats":["astro-ph.CO"],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2018-08-15T18:37:10Z","title":"The Evolution of the HeII-Ionizing Background at Redshifts 2.3<z<3.8 Inferred from a Statistical Sample of 24 HST/COS HeII Ly$\\alpha$ Absorption Spectra"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1808.05247","kind":"arxiv","version":2},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:431c413b0393d1a9d119bb0ee86dc2cfec21000699b86aa469caf21e2dad6292","target":"record","created_at":"2026-05-17T23:47:20Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"adb48d2390f9baae2254100109877c2ca6ad53c59491c33961cacf684d2c4a42","cross_cats_sorted":["astro-ph.CO"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.GA","submitted_at":"2018-08-15T18:37:10Z","title_canon_sha256":"4ac6016f775248648e35a318b0271bcb42ffb8423e6ac64b73a8dc5e6248dc33"},"schema_version":"1.0","source":{"id":"1808.05247","kind":"arxiv","version":2}},"canonical_sha256":"2f19162c1400fb5dcbcdbd71609b183a6591ea59725f77d33fd5f40d7e37c5c1","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"2f19162c1400fb5dcbcdbd71609b183a6591ea59725f77d33fd5f40d7e37c5c1","first_computed_at":"2026-05-17T23:47:20.653300Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-17T23:47:20.653300Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"PbzAIgzaePtnhQpEJbWhdNGexMKbx81wkNp2Vot+HxqgLuyooegj0tnIG59xyfmWJmJc55bCtfXbITFi1HebDQ==","signature_status":"signed_v1","signed_at":"2026-05-17T23:47:20.653775Z","signed_message":"canonical_sha256_bytes"},"source_id":"1808.05247","source_kind":"arxiv","source_version":2}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:431c413b0393d1a9d119bb0ee86dc2cfec21000699b86aa469caf21e2dad6292","sha256:9f88f4206d22a2f8d7403e1b02fc8f3b70a6976c7e9b0ad3ccb0facf20915eb0"],"state_sha256":"671bd8161ad5ed47305d5f141fdae2f17406a67dff71b7ee6a6a84e1c6ae42ed"}