{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2018:N4FAPQN66CXKVEZNI5HRG3ZIDE","short_pith_number":"pith:N4FAPQN6","canonical_record":{"source":{"id":"1803.04505","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2018-03-12T20:11:55Z","cross_cats_sorted":[],"title_canon_sha256":"df2a2525f7cd6b634c0d89b8c9a18d5e398a84b99bf9198fde4053e0dadaf357","abstract_canon_sha256":"207de0a4ed8af708b74e06eabd6315d811ce42b3b785f7df712283ab72ef6f82"},"schema_version":"1.0"},"canonical_sha256":"6f0a07c1bef0aeaa932d474f136f281918fc710e18cae3259ed51eff651c2f1c","source":{"kind":"arxiv","id":"1803.04505","version":2},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1803.04505","created_at":"2026-05-18T00:06:56Z"},{"alias_kind":"arxiv_version","alias_value":"1803.04505v2","created_at":"2026-05-18T00:06:56Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1803.04505","created_at":"2026-05-18T00:06:56Z"},{"alias_kind":"pith_short_12","alias_value":"N4FAPQN66CXK","created_at":"2026-05-18T12:32:40Z"},{"alias_kind":"pith_short_16","alias_value":"N4FAPQN66CXKVEZN","created_at":"2026-05-18T12:32:40Z"},{"alias_kind":"pith_short_8","alias_value":"N4FAPQN6","created_at":"2026-05-18T12:32:40Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2018:N4FAPQN66CXKVEZNI5HRG3ZIDE","target":"record","payload":{"canonical_record":{"source":{"id":"1803.04505","kind":"arxiv","version":2},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2018-03-12T20:11:55Z","cross_cats_sorted":[],"title_canon_sha256":"df2a2525f7cd6b634c0d89b8c9a18d5e398a84b99bf9198fde4053e0dadaf357","abstract_canon_sha256":"207de0a4ed8af708b74e06eabd6315d811ce42b3b785f7df712283ab72ef6f82"},"schema_version":"1.0"},"canonical_sha256":"6f0a07c1bef0aeaa932d474f136f281918fc710e18cae3259ed51eff651c2f1c","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:06:56.220079Z","signature_b64":"PRC0jl5FRW8OCHiP12gcCNbXSu5XzREOzBWWGmu6D6PvalzNGXRDwoNtYBn/H+6buOjVaFhUZ/CTM6fjnd3OBQ==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"6f0a07c1bef0aeaa932d474f136f281918fc710e18cae3259ed51eff651c2f1c","last_reissued_at":"2026-05-18T00:06:56.219532Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:06:56.219532Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1803.04505","source_version":2,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:06:56Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"NiySRyib1vbFaO+RheojPKBmzjHmuZ+a8xKo8bZjebJ6+K0hs6t9ekHcVXwGAupvTOptC5bFp6YasJGEx886Ag==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-25T20:40:49.114584Z"},"content_sha256":"56c65538d4fb387752d5e8f5b1f644e5f7fa35b0a7e04b739ae47f14d796143b","schema_version":"1.0","event_id":"sha256:56c65538d4fb387752d5e8f5b1f644e5f7fa35b0a7e04b739ae47f14d796143b"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2018:N4FAPQN66CXKVEZNI5HRG3ZIDE","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Exploring circular polarization in the CMB due to conventional sources of cosmic birefringence","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.CO","authors_text":"Christopher M. Hirata, Paulo Montero-Camacho","submitted_at":"2018-03-12T20:11:55Z","abstract_excerpt":"The circular polarization of the cosmic microwave background (CMB) is usually taken to be zero since it is not generated by Thomson scattering. Here we explore the actual level of circular polarization in the CMB generated by conventional cosmological sources of birefringence. We consider two classes of mechanisms for birefringence. One is alignment of the matter to produce an anisotropic susceptibility tensor: the hydrogen spins can be aligned either by density perturbations or CMB anisotropies themselves. The other is anisotropy of the radiation field coupled to the non-linear response of th"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1803.04505","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"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:06:56Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"QWa6WfTgYjcb4UgAj7EqehW4jXlk6Z0Nrj3dqvG+VAUBCazaCPwOxulsp9JJ601LT7vk7xL63ZVWWWmx1yT4Cg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-25T20:40:49.115327Z"},"content_sha256":"3d579bdf40b3efd19b6ed37efe0b5987aba37d914bf54af5757bd36245aaca2d","schema_version":"1.0","event_id":"sha256:3d579bdf40b3efd19b6ed37efe0b5987aba37d914bf54af5757bd36245aaca2d"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/N4FAPQN66CXKVEZNI5HRG3ZIDE/bundle.json","state_url":"https://pith.science/pith/N4FAPQN66CXKVEZNI5HRG3ZIDE/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/N4FAPQN66CXKVEZNI5HRG3ZIDE/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":"2026-05-25T20:40:49Z","links":{"resolver":"https://pith.science/pith/N4FAPQN66CXKVEZNI5HRG3ZIDE","bundle":"https://pith.science/pith/N4FAPQN66CXKVEZNI5HRG3ZIDE/bundle.json","state":"https://pith.science/pith/N4FAPQN66CXKVEZNI5HRG3ZIDE/state.json","well_known_bundle":"https://pith.science/.well-known/pith/N4FAPQN66CXKVEZNI5HRG3ZIDE/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2018:N4FAPQN66CXKVEZNI5HRG3ZIDE","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":"207de0a4ed8af708b74e06eabd6315d811ce42b3b785f7df712283ab72ef6f82","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2018-03-12T20:11:55Z","title_canon_sha256":"df2a2525f7cd6b634c0d89b8c9a18d5e398a84b99bf9198fde4053e0dadaf357"},"schema_version":"1.0","source":{"id":"1803.04505","kind":"arxiv","version":2}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1803.04505","created_at":"2026-05-18T00:06:56Z"},{"alias_kind":"arxiv_version","alias_value":"1803.04505v2","created_at":"2026-05-18T00:06:56Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1803.04505","created_at":"2026-05-18T00:06:56Z"},{"alias_kind":"pith_short_12","alias_value":"N4FAPQN66CXK","created_at":"2026-05-18T12:32:40Z"},{"alias_kind":"pith_short_16","alias_value":"N4FAPQN66CXKVEZN","created_at":"2026-05-18T12:32:40Z"},{"alias_kind":"pith_short_8","alias_value":"N4FAPQN6","created_at":"2026-05-18T12:32:40Z"}],"graph_snapshots":[{"event_id":"sha256:3d579bdf40b3efd19b6ed37efe0b5987aba37d914bf54af5757bd36245aaca2d","target":"graph","created_at":"2026-05-18T00:06:56Z","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 circular polarization of the cosmic microwave background (CMB) is usually taken to be zero since it is not generated by Thomson scattering. Here we explore the actual level of circular polarization in the CMB generated by conventional cosmological sources of birefringence. We consider two classes of mechanisms for birefringence. One is alignment of the matter to produce an anisotropic susceptibility tensor: the hydrogen spins can be aligned either by density perturbations or CMB anisotropies themselves. The other is anisotropy of the radiation field coupled to the non-linear response of th","authors_text":"Christopher M. Hirata, Paulo Montero-Camacho","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2018-03-12T20:11:55Z","title":"Exploring circular polarization in the CMB due to conventional sources of cosmic birefringence"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1803.04505","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":"sha256:56c65538d4fb387752d5e8f5b1f644e5f7fa35b0a7e04b739ae47f14d796143b","target":"record","created_at":"2026-05-18T00:06:56Z","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":"207de0a4ed8af708b74e06eabd6315d811ce42b3b785f7df712283ab72ef6f82","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.CO","submitted_at":"2018-03-12T20:11:55Z","title_canon_sha256":"df2a2525f7cd6b634c0d89b8c9a18d5e398a84b99bf9198fde4053e0dadaf357"},"schema_version":"1.0","source":{"id":"1803.04505","kind":"arxiv","version":2}},"canonical_sha256":"6f0a07c1bef0aeaa932d474f136f281918fc710e18cae3259ed51eff651c2f1c","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"6f0a07c1bef0aeaa932d474f136f281918fc710e18cae3259ed51eff651c2f1c","first_computed_at":"2026-05-18T00:06:56.219532Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:06:56.219532Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"PRC0jl5FRW8OCHiP12gcCNbXSu5XzREOzBWWGmu6D6PvalzNGXRDwoNtYBn/H+6buOjVaFhUZ/CTM6fjnd3OBQ==","signature_status":"signed_v1","signed_at":"2026-05-18T00:06:56.220079Z","signed_message":"canonical_sha256_bytes"},"source_id":"1803.04505","source_kind":"arxiv","source_version":2}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:56c65538d4fb387752d5e8f5b1f644e5f7fa35b0a7e04b739ae47f14d796143b","sha256:3d579bdf40b3efd19b6ed37efe0b5987aba37d914bf54af5757bd36245aaca2d"],"state_sha256":"e7e3c3b7af4676249df518550e57902130c1acb16b5372c46645a27053589cbb"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"3AfWiA7cgql5TPcaZ2kxOVqyHLmdcAJBAjI3HLMA0+2XkMiEZbZEfbiai0bFEYeLM+0brOpo3hu0LZNSwRQxCA==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-25T20:40:49.119136Z","bundle_sha256":"2a4ca50019d0658374bcbec719c5198e87ef27dda073a35df1b464f9c0ae60e6"}}