{"paper":{"title":"Variability of Sagittarius A* at 3 GHz on minute-scale with MeerKAT","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Sgr A* shows flux variations on tens-of-minute timescales at 2.79 GHz with 6.11% modulation.","cross_cats":["astro-ph.HE"],"primary_cat":"astro-ph.GA","authors_text":"A. Basu, A. Brunthaler, C. K\\\"onig, D.J. Champion, E.D. Barr, G. Witzel, H.-R. Kl\\\"ockner, I. Rammala-Zitha, J.D. Wagenveld, K. Kaur, M. Hoeft, M. Kramer, M. Wielgus, O. Wucknitz, P.V. Padmanabh, R.S. Wharton, S.A. Mao, S. Buchner, S. Khan, S. Ranchod, S.S. Sridhar, V. Balakrishnan, V. Venkatraman Krishnan, Y.K. Ma","submitted_at":"2026-04-24T15:13:57Z","abstract_excerpt":"The supermassive black hole Sagittarius A* (Sgr A*) exhibits temporal and spectral variability across the electromagnetic spectrum. However, variability at radio frequencies below ~ 5 GHz for timescales shorter than a day remains largely unexplored. We investigate the variability of Sgr A* at 2.79 GHz on short timescales (1 min), to probe an under-explored regime of its emission process. Through point-source model fitting in the uv-domain, we analyse the flux density variation of Sgr A* over an 8 h observation. We detect flux variation on a few tens of minute timescale with a modulation index "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"We detect flux variation on a few tens of minute timescale with a modulation index of 6.11 %, a mean flux density of (827 ± 0.1_stat ± 33_sys) mJy, and a mean spectral slope of 0.08±0.03. Furthermore, we measure the slope of the structure function of the observed light curve as 0.81 ± 0.05 with a characteristic timescale of about 120 min.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The point-source model fitting in the uv-domain fully isolates intrinsic Sgr A* variability without significant contamination from interstellar scintillation, residual calibration errors, or nearby source confusion.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Sgr A* shows 6.11% flux modulation on ~30-minute scales at 3 GHz with structure function slope 0.81 and ~120 min characteristic timescale.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Sgr A* shows flux variations on tens-of-minute timescales at 2.79 GHz with 6.11% modulation.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"f447d334db9090604bcaef107e5545b913ef5fe0fda088ace74f2b24084bc41e"},"source":{"id":"2604.22638","kind":"arxiv","version":1},"verdict":{"id":"d9f4c139-2d60-4ff9-8b7b-8e0b851d9c5e","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-08T10:57:50.031676Z","strongest_claim":"We detect flux variation on a few tens of minute timescale with a modulation index of 6.11 %, a mean flux density of (827 ± 0.1_stat ± 33_sys) mJy, and a mean spectral slope of 0.08±0.03. Furthermore, we measure the slope of the structure function of the observed light curve as 0.81 ± 0.05 with a characteristic timescale of about 120 min.","one_line_summary":"Sgr A* shows 6.11% flux modulation on ~30-minute scales at 3 GHz with structure function slope 0.81 and ~120 min characteristic timescale.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The point-source model fitting in the uv-domain fully isolates intrinsic Sgr A* variability without significant contamination from interstellar scintillation, residual calibration errors, or nearby source confusion.","pith_extraction_headline":"Sgr A* shows flux variations on tens-of-minute timescales at 2.79 GHz with 6.11% modulation."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2604.22638/integrity.json","findings":[],"available":true,"detectors_run":[{"name":"ai_meta_artifact","ran_at":"2026-05-21T10:36:20.021200Z","status":"completed","version":"1.0.0","findings_count":0},{"name":"doi_compliance","ran_at":"2026-05-19T23:46:54.124654Z","status":"completed","version":"1.0.0","findings_count":0}],"snapshot_sha256":"b6ddadc884b699ee806aa4accd6109738f29ed246e3a131959244ebc48112640"},"references":{"count":2,"sample":[{"doi":"","year":1997,"title":"1997, in Astrophysics and Space Science Library, V ol","work_id":"a156d4b2-4d04-427f-8cf9-811db9b81fb4","ref_index":1,"cited_arxiv_id":"1805.01242","is_internal_anchor":false},{"doi":"","year":2021,"title":"in CASA to perform a single-component model fitting to theuv- data, estimating the flux density of the source. A.4. Source Isolation and Primary Beam Correction Given the complexity of the GC environm","work_id":"ab1ce80c-fc6e-46aa-b8c4-846d0cebe8b1","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":2,"snapshot_sha256":"0940eb0a50ae8b6d49b06b0dcb1dab49775e9c2a6d0086348b4100374929554d","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"}