{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2021:6NSVCIH6K2X34X4SXDGEGJ6PF4","short_pith_number":"pith:6NSVCIH6","canonical_record":{"source":{"id":"2109.11831","kind":"arxiv","version":1},"metadata":{"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-09-24T09:20:37Z","cross_cats_sorted":["hep-ph","hep-th"],"title_canon_sha256":"69910ece7e1092e3062f2bfff2212e17b818c733d4bd2a77a2000cfababe3ebb","abstract_canon_sha256":"bd3cdb0dfcfb7c6aa751f0a49bc5d4b027ac09287f998c2cf5837f7898b5b5a9"},"schema_version":"1.0"},"canonical_sha256":"f3655120fe56afbe5f92b8cc4327cf2f006bc4ff67ca7a8e91f9297bf227c3af","source":{"kind":"arxiv","id":"2109.11831","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"2109.11831","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"arxiv_version","alias_value":"2109.11831v1","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2109.11831","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"pith_short_12","alias_value":"6NSVCIH6K2X3","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"pith_short_16","alias_value":"6NSVCIH6K2X34X4S","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"pith_short_8","alias_value":"6NSVCIH6","created_at":"2026-07-05T03:17:33Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2021:6NSVCIH6K2X34X4SXDGEGJ6PF4","target":"record","payload":{"canonical_record":{"source":{"id":"2109.11831","kind":"arxiv","version":1},"metadata":{"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-09-24T09:20:37Z","cross_cats_sorted":["hep-ph","hep-th"],"title_canon_sha256":"69910ece7e1092e3062f2bfff2212e17b818c733d4bd2a77a2000cfababe3ebb","abstract_canon_sha256":"bd3cdb0dfcfb7c6aa751f0a49bc5d4b027ac09287f998c2cf5837f7898b5b5a9"},"schema_version":"1.0"},"canonical_sha256":"f3655120fe56afbe5f92b8cc4327cf2f006bc4ff67ca7a8e91f9297bf227c3af","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-07-05T03:17:33.996519Z","signature_b64":"jgZZmPVMYYLVkjxUHNaqNJ0mOvQrZuwmFKD5v5kQ3HTMuUrzI3ZACsEISY5ZUsHRRK6zMUrZtH6Yw7SiX06NDw==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"f3655120fe56afbe5f92b8cc4327cf2f006bc4ff67ca7a8e91f9297bf227c3af","last_reissued_at":"2026-07-05T03:17:33.996140Z","signature_status":"signed_v1","first_computed_at":"2026-07-05T03:17:33.996140Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"2109.11831","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":"2026-07-05T03:17:33Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"CdTLnC/hOF40xAGTEV+YmzEKg5NJ5KCw/iNy6Cq15Yos1AUy2lfKiT2rOEOZUO0wgq5BbWbY1vYs6qLaxwhUDg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-08-11T21:56:14.083686Z"},"content_sha256":"2041e18f8268dee39929e2b75ef0aa8f3e8b283e3284a6f14308ae4befccb3d2","schema_version":"1.0","event_id":"sha256:2041e18f8268dee39929e2b75ef0aa8f3e8b283e3284a6f14308ae4befccb3d2"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2021:6NSVCIH6K2X34X4SXDGEGJ6PF4","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Phonon emission by acoustic black holes","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["hep-ph","hep-th"],"primary_cat":"gr-qc","authors_text":"Dario Grasso, Maria Luisa Chiofalo, Massimo Mannarelli, Silvia Trabucco","submitted_at":"2021-09-24T09:20:37Z","abstract_excerpt":"We present a novel interpretation of the Hawking temperature of acoustic holes, the hydrodynamic analogue of standard black holes, by connecting the geometrical properties of the horizon with the distribution function of the spontaneously generated phonons. Using covariant kinetic theory to describe the phonon gas emitted by the acoustic hole, we obtain the correct expression of the Hawking temperature by equating the entropy loss of the acoustic horizon with the entropy gain of the phonon gas. In doing this, we assume that the entropy of the acoustic hole is proportional to the area of the ho"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2109.11831","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":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2109.11831/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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":"2026-07-05T03:17:33Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"rAqH68FZFXPOTs6bTV2nccZ4wX2GQanNNjag/Q1nDv/NWaVrO0i+k3TYBfzBtsfvQu0GMqIjmm/931TFA0wsCg==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-08-11T21:56:14.084984Z"},"content_sha256":"2b70fd32a180d8440f5141e0a41d7da8d73a2a8aeaaf6461ff6bed8ead4fd354","schema_version":"1.0","event_id":"sha256:2b70fd32a180d8440f5141e0a41d7da8d73a2a8aeaaf6461ff6bed8ead4fd354"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/6NSVCIH6K2X34X4SXDGEGJ6PF4/bundle.json","state_url":"https://pith.science/pith/6NSVCIH6K2X34X4SXDGEGJ6PF4/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/6NSVCIH6K2X34X4SXDGEGJ6PF4/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":"2026-08-11T21:56:14Z","links":{"resolver":"https://pith.science/pith/6NSVCIH6K2X34X4SXDGEGJ6PF4","bundle":"https://pith.science/pith/6NSVCIH6K2X34X4SXDGEGJ6PF4/bundle.json","state":"https://pith.science/pith/6NSVCIH6K2X34X4SXDGEGJ6PF4/state.json","well_known_bundle":"https://pith.science/.well-known/pith/6NSVCIH6K2X34X4SXDGEGJ6PF4/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2021:6NSVCIH6K2X34X4SXDGEGJ6PF4","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":"bd3cdb0dfcfb7c6aa751f0a49bc5d4b027ac09287f998c2cf5837f7898b5b5a9","cross_cats_sorted":["hep-ph","hep-th"],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-09-24T09:20:37Z","title_canon_sha256":"69910ece7e1092e3062f2bfff2212e17b818c733d4bd2a77a2000cfababe3ebb"},"schema_version":"1.0","source":{"id":"2109.11831","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"2109.11831","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"arxiv_version","alias_value":"2109.11831v1","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2109.11831","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"pith_short_12","alias_value":"6NSVCIH6K2X3","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"pith_short_16","alias_value":"6NSVCIH6K2X34X4S","created_at":"2026-07-05T03:17:33Z"},{"alias_kind":"pith_short_8","alias_value":"6NSVCIH6","created_at":"2026-07-05T03:17:33Z"}],"graph_snapshots":[{"event_id":"sha256:2b70fd32a180d8440f5141e0a41d7da8d73a2a8aeaaf6461ff6bed8ead4fd354","target":"graph","created_at":"2026-07-05T03:17:33Z","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"},"integrity":{"available":true,"clean":true,"detectors_run":[],"endpoint":"/pith/2109.11831/integrity.json","findings":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938","summary":{"advisory":0,"by_detector":{},"critical":0,"informational":0}},"paper":{"abstract_excerpt":"We present a novel interpretation of the Hawking temperature of acoustic holes, the hydrodynamic analogue of standard black holes, by connecting the geometrical properties of the horizon with the distribution function of the spontaneously generated phonons. Using covariant kinetic theory to describe the phonon gas emitted by the acoustic hole, we obtain the correct expression of the Hawking temperature by equating the entropy loss of the acoustic horizon with the entropy gain of the phonon gas. In doing this, we assume that the entropy of the acoustic hole is proportional to the area of the ho","authors_text":"Dario Grasso, Maria Luisa Chiofalo, Massimo Mannarelli, Silvia Trabucco","cross_cats":["hep-ph","hep-th"],"headline":"","license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-09-24T09:20:37Z","title":"Phonon emission by acoustic black holes"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2109.11831","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":"sha256:2041e18f8268dee39929e2b75ef0aa8f3e8b283e3284a6f14308ae4befccb3d2","target":"record","created_at":"2026-07-05T03:17:33Z","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":"bd3cdb0dfcfb7c6aa751f0a49bc5d4b027ac09287f998c2cf5837f7898b5b5a9","cross_cats_sorted":["hep-ph","hep-th"],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-09-24T09:20:37Z","title_canon_sha256":"69910ece7e1092e3062f2bfff2212e17b818c733d4bd2a77a2000cfababe3ebb"},"schema_version":"1.0","source":{"id":"2109.11831","kind":"arxiv","version":1}},"canonical_sha256":"f3655120fe56afbe5f92b8cc4327cf2f006bc4ff67ca7a8e91f9297bf227c3af","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"f3655120fe56afbe5f92b8cc4327cf2f006bc4ff67ca7a8e91f9297bf227c3af","first_computed_at":"2026-07-05T03:17:33.996140Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-07-05T03:17:33.996140Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"jgZZmPVMYYLVkjxUHNaqNJ0mOvQrZuwmFKD5v5kQ3HTMuUrzI3ZACsEISY5ZUsHRRK6zMUrZtH6Yw7SiX06NDw==","signature_status":"signed_v1","signed_at":"2026-07-05T03:17:33.996519Z","signed_message":"canonical_sha256_bytes"},"source_id":"2109.11831","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:2041e18f8268dee39929e2b75ef0aa8f3e8b283e3284a6f14308ae4befccb3d2","sha256:2b70fd32a180d8440f5141e0a41d7da8d73a2a8aeaaf6461ff6bed8ead4fd354"],"state_sha256":"b04a56ab6acda63a5ef71a02ddf8d856647c6bf33e107730b462796c3c0d21f8"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"9chj+xRa9iMchk+BIdt+LubZ9+a1Q68AMRl5MwpG7GhFQBmEOpXAuSU3n0DNT74qfaQqXdj9/DjCi7ZrPop2AA==","signed_message":"bundle_sha256_bytes","signed_at":"2026-08-11T21:56:14.106473Z","bundle_sha256":"7dc6f5e38366f051d4457e121def0b9ca32c3ebdf03510b42c1513a6e4c0b5eb"}}