{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2013:2PSP577UYRC3NUQQKIQXI5MMDE","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":"4c9987f0f3eb3398fed52b92fd25a9f7d3a81f6b315370b206ada5253733aa23","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2013-04-15T20:00:04Z","title_canon_sha256":"8fe0ab4544808cf18e2df7b1f753cfd66004f95aac89ac6705b4f0dccaef8086"},"schema_version":"1.0","source":{"id":"1304.4235","kind":"arxiv","version":2}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1304.4235","created_at":"2026-05-18T03:17:46Z"},{"alias_kind":"arxiv_version","alias_value":"1304.4235v2","created_at":"2026-05-18T03:17:46Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1304.4235","created_at":"2026-05-18T03:17:46Z"},{"alias_kind":"pith_short_12","alias_value":"2PSP577UYRC3","created_at":"2026-05-18T12:27:32Z"},{"alias_kind":"pith_short_16","alias_value":"2PSP577UYRC3NUQQ","created_at":"2026-05-18T12:27:32Z"},{"alias_kind":"pith_short_8","alias_value":"2PSP577U","created_at":"2026-05-18T12:27:32Z"}],"graph_snapshots":[{"event_id":"sha256:b66700aa666eb6bfc7c52aa035d5089b48118cb8341bee4d324628f0cd2e57c0","target":"graph","created_at":"2026-05-18T03:17:46Z","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 describe URCHIN, a reverse ray tracing radiative transfer scheme optimised to model self-shielding from the post-reionisation ultraviolet (UV) background in cosmological simulations. The reverse ray tracing strategy provides several benefits over forward ray tracing codes including: (1) the preservation of adaptive density field resolution (2) completely uniform sampling of gas elements by rays; (3) the preservation of galilean invariance; (4) the ability to sample the UV background spectrum with hundreds of frequency bins; and (5) exact preservation of the input UV background spectrum and ","authors_text":"Gabriel Altay, Tom Theuns","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2013-04-15T20:00:04Z","title":"Urchin: A Reverse Ray Tracer for Astrophysical Applications"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1304.4235","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:d4e56e60b46f99064aa042b06a44f962322316160f5c464e9c39b2314ed1fd17","target":"record","created_at":"2026-05-18T03:17:46Z","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":"4c9987f0f3eb3398fed52b92fd25a9f7d3a81f6b315370b206ada5253733aa23","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2013-04-15T20:00:04Z","title_canon_sha256":"8fe0ab4544808cf18e2df7b1f753cfd66004f95aac89ac6705b4f0dccaef8086"},"schema_version":"1.0","source":{"id":"1304.4235","kind":"arxiv","version":2}},"canonical_sha256":"d3e4fefff4c445b6d210522174758c1906219e3f53d9165503c748e8adb07832","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"d3e4fefff4c445b6d210522174758c1906219e3f53d9165503c748e8adb07832","first_computed_at":"2026-05-18T03:17:46.439424Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T03:17:46.439424Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"QhrC12QG0k5Cko6Ko5HqYYjeT0ZseWEuJ90h8B6lHJ1QxQl2G5kmZYeZsyKe1RWpSrhLLEmBwWtWlO2PW96bCA==","signature_status":"signed_v1","signed_at":"2026-05-18T03:17:46.440160Z","signed_message":"canonical_sha256_bytes"},"source_id":"1304.4235","source_kind":"arxiv","source_version":2}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:d4e56e60b46f99064aa042b06a44f962322316160f5c464e9c39b2314ed1fd17","sha256:b66700aa666eb6bfc7c52aa035d5089b48118cb8341bee4d324628f0cd2e57c0"],"state_sha256":"9371ce3c7d3f910bfaf2c9fbaa90dc91ebcda19d76fe56285ad412fd46b499ba"}