{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2004:HVVEBW7N2ECXFW5FWLEIJ6YLOP","short_pith_number":"pith:HVVEBW7N","canonical_record":{"source":{"id":"astro-ph/0403693","kind":"arxiv","version":1},"metadata":{"license":"","primary_cat":"astro-ph","submitted_at":"2004-03-30T21:01:22Z","cross_cats_sorted":[],"title_canon_sha256":"f6094eeae458de796266d6b0ff2241942d3f9cf28133ccd40693feca2ed30957","abstract_canon_sha256":"a928aaf5408106cb32bcf4cc6604407e00a477bafe9be5348dea2102eef587ae"},"schema_version":"1.0"},"canonical_sha256":"3d6a40dbedd10572dba5b2c884fb0b73f51c4cb06f56aa85330f75b5f0aa648a","source":{"kind":"arxiv","id":"astro-ph/0403693","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"astro-ph/0403693","created_at":"2026-05-18T01:21:50Z"},{"alias_kind":"arxiv_version","alias_value":"astro-ph/0403693v1","created_at":"2026-05-18T01:21:50Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.astro-ph/0403693","created_at":"2026-05-18T01:21:50Z"},{"alias_kind":"pith_short_12","alias_value":"HVVEBW7N2ECX","created_at":"2026-05-18T12:25:52Z"},{"alias_kind":"pith_short_16","alias_value":"HVVEBW7N2ECXFW5F","created_at":"2026-05-18T12:25:52Z"},{"alias_kind":"pith_short_8","alias_value":"HVVEBW7N","created_at":"2026-05-18T12:25:52Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2004:HVVEBW7N2ECXFW5FWLEIJ6YLOP","target":"record","payload":{"canonical_record":{"source":{"id":"astro-ph/0403693","kind":"arxiv","version":1},"metadata":{"license":"","primary_cat":"astro-ph","submitted_at":"2004-03-30T21:01:22Z","cross_cats_sorted":[],"title_canon_sha256":"f6094eeae458de796266d6b0ff2241942d3f9cf28133ccd40693feca2ed30957","abstract_canon_sha256":"a928aaf5408106cb32bcf4cc6604407e00a477bafe9be5348dea2102eef587ae"},"schema_version":"1.0"},"canonical_sha256":"3d6a40dbedd10572dba5b2c884fb0b73f51c4cb06f56aa85330f75b5f0aa648a","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T01:21:50.241909Z","signature_b64":"hL0UuP5GsTOP1krM4jIm/ayC3t+fTCVglnzNpFhvuFC76R68dLgcYsegwTxycvE6LJNDIb6uTDklKAR2Kc9ZCw==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"3d6a40dbedd10572dba5b2c884fb0b73f51c4cb06f56aa85330f75b5f0aa648a","last_reissued_at":"2026-05-18T01:21:50.241221Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T01:21:50.241221Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"astro-ph/0403693","source_version":1,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:21:50Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"VCHJLZFA3h2ow45FyR8Bo+/tTCMl+klEpR7t+bC0DT7CPE6hW4cyVH0KSP56IzbwdzHz/HGe7M5Ke5iYLy5IDg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-26T15:46:55.830089Z"},"content_sha256":"417c3a2332850495006e03028fcdb871e3896e65d81401ce298be559b55c895c","schema_version":"1.0","event_id":"sha256:417c3a2332850495006e03028fcdb871e3896e65d81401ce298be559b55c895c"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2004:HVVEBW7N2ECXFW5FWLEIJ6YLOP","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Compton Thick AGN: the dark side of the X-ray background","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"Andrea Comastri (INAF-Osservatorio Astronomico di Bologna)","submitted_at":"2004-03-30T21:01:22Z","abstract_excerpt":"The spectrum of the hard X-ray background records the history of accretion processes integrated over the cosmic time. Several pieces of observational and theoretical evidence indicate that a significant fraction of the energy density is obscured by large columns of gas and dust. The absorbing matter is often very thick, with column densities exceeding N_H > 1.5 10^24 cm-2, the value corresponding to unity optical depth for Compton scattering. These sources are called ``Compton thick'' and appear to be very numerous, at least in the nearby universe. Although Compton thick Active Galactic Nuclei"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0403693","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"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:21:50Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"zp+KFAz3bJNnfgR4B2KxzuXYtMAzREjNJ5JLluhmMDklZ+bUDR1QL0taodCc1Un1UE9QUm3FWcD9iJp5z5QJDg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-26T15:46:55.830456Z"},"content_sha256":"f16626735508f8dc4dc911efc6459b4abe3d4a6955d0ed98d289d1bb9046d924","schema_version":"1.0","event_id":"sha256:f16626735508f8dc4dc911efc6459b4abe3d4a6955d0ed98d289d1bb9046d924"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/HVVEBW7N2ECXFW5FWLEIJ6YLOP/bundle.json","state_url":"https://pith.science/pith/HVVEBW7N2ECXFW5FWLEIJ6YLOP/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/HVVEBW7N2ECXFW5FWLEIJ6YLOP/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-05-26T15:46:55Z","links":{"resolver":"https://pith.science/pith/HVVEBW7N2ECXFW5FWLEIJ6YLOP","bundle":"https://pith.science/pith/HVVEBW7N2ECXFW5FWLEIJ6YLOP/bundle.json","state":"https://pith.science/pith/HVVEBW7N2ECXFW5FWLEIJ6YLOP/state.json","well_known_bundle":"https://pith.science/.well-known/pith/HVVEBW7N2ECXFW5FWLEIJ6YLOP/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2004:HVVEBW7N2ECXFW5FWLEIJ6YLOP","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":"a928aaf5408106cb32bcf4cc6604407e00a477bafe9be5348dea2102eef587ae","cross_cats_sorted":[],"license":"","primary_cat":"astro-ph","submitted_at":"2004-03-30T21:01:22Z","title_canon_sha256":"f6094eeae458de796266d6b0ff2241942d3f9cf28133ccd40693feca2ed30957"},"schema_version":"1.0","source":{"id":"astro-ph/0403693","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"astro-ph/0403693","created_at":"2026-05-18T01:21:50Z"},{"alias_kind":"arxiv_version","alias_value":"astro-ph/0403693v1","created_at":"2026-05-18T01:21:50Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.astro-ph/0403693","created_at":"2026-05-18T01:21:50Z"},{"alias_kind":"pith_short_12","alias_value":"HVVEBW7N2ECX","created_at":"2026-05-18T12:25:52Z"},{"alias_kind":"pith_short_16","alias_value":"HVVEBW7N2ECXFW5F","created_at":"2026-05-18T12:25:52Z"},{"alias_kind":"pith_short_8","alias_value":"HVVEBW7N","created_at":"2026-05-18T12:25:52Z"}],"graph_snapshots":[{"event_id":"sha256:f16626735508f8dc4dc911efc6459b4abe3d4a6955d0ed98d289d1bb9046d924","target":"graph","created_at":"2026-05-18T01:21:50Z","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":"The spectrum of the hard X-ray background records the history of accretion processes integrated over the cosmic time. Several pieces of observational and theoretical evidence indicate that a significant fraction of the energy density is obscured by large columns of gas and dust. The absorbing matter is often very thick, with column densities exceeding N_H > 1.5 10^24 cm-2, the value corresponding to unity optical depth for Compton scattering. These sources are called ``Compton thick'' and appear to be very numerous, at least in the nearby universe. Although Compton thick Active Galactic Nuclei","authors_text":"Andrea Comastri (INAF-Osservatorio Astronomico di Bologna)","cross_cats":[],"headline":"","license":"","primary_cat":"astro-ph","submitted_at":"2004-03-30T21:01:22Z","title":"Compton Thick AGN: the dark side of the X-ray background"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0403693","kind":"arxiv","version":1},"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":"sha256:417c3a2332850495006e03028fcdb871e3896e65d81401ce298be559b55c895c","target":"record","created_at":"2026-05-18T01:21:50Z","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":"a928aaf5408106cb32bcf4cc6604407e00a477bafe9be5348dea2102eef587ae","cross_cats_sorted":[],"license":"","primary_cat":"astro-ph","submitted_at":"2004-03-30T21:01:22Z","title_canon_sha256":"f6094eeae458de796266d6b0ff2241942d3f9cf28133ccd40693feca2ed30957"},"schema_version":"1.0","source":{"id":"astro-ph/0403693","kind":"arxiv","version":1}},"canonical_sha256":"3d6a40dbedd10572dba5b2c884fb0b73f51c4cb06f56aa85330f75b5f0aa648a","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"3d6a40dbedd10572dba5b2c884fb0b73f51c4cb06f56aa85330f75b5f0aa648a","first_computed_at":"2026-05-18T01:21:50.241221Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T01:21:50.241221Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"hL0UuP5GsTOP1krM4jIm/ayC3t+fTCVglnzNpFhvuFC76R68dLgcYsegwTxycvE6LJNDIb6uTDklKAR2Kc9ZCw==","signature_status":"signed_v1","signed_at":"2026-05-18T01:21:50.241909Z","signed_message":"canonical_sha256_bytes"},"source_id":"astro-ph/0403693","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:417c3a2332850495006e03028fcdb871e3896e65d81401ce298be559b55c895c","sha256:f16626735508f8dc4dc911efc6459b4abe3d4a6955d0ed98d289d1bb9046d924"],"state_sha256":"f7cf03eb1c5fb51e4bc1debc538eee6ca6ed559afa0b0937508bdd0ee3d70641"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"R+HAsFgFM6PQ9QEvqQ7pTyiyrq8UK7rG4x3yz1Bt9H1bQAtGANMt40nx79o8clVM3Y1lRH/r9zMvyuxiMXK3CA==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-26T15:46:55.832819Z","bundle_sha256":"ea5640d91b1ca40fec745654f9d8adab9ea3983d03420e40b7777f1c582fc211"}}