{"paper":{"title":"Significant or Not? The Impact of Randomisation During Data Reduction on Confirming a New Pulsating Ultraluminous X-ray Source Candidate in Centaurus A","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Randomisation during XMM-Newton data reduction introduces considerable uncertainty in confirming marginal pulsations from a new ultraluminous X-ray source candidate in Centaurus A.","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"Alistair T. Pagan, Amy H. Knight, Callum Potter, Dominic J. Walton, Timothy P. Roberts","submitted_at":"2026-05-14T17:43:03Z","abstract_excerpt":"We report the discovery of a new candidate pulsating ultraluminous X-ray source (PULX) in NGC 5128 (Centaurus A). The candidate, 4XMM J132542.2-425943, is a transient source, identifiable as a clear X-ray point source for $\\sim 8$ months in 2014, during its only major recorded outburst. The source flux exceeded $10^{-12}$ erg cm$^{-2}$ s$^{-1}$ at the peak of the outburst. The long-term light curve of 4XMM J132542.2-425943 shows two further, less luminous detections in 2017 and 2024, but was otherwise in quiescence. This behaviour is similar to the class of pulsating transients with outbursts "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"the intrinsic randomisation employed by XMM-Newton's Science Analysis Software, XMM-SAS, during the data reduction procedure introduces considerable uncertainty in the strength of our marginal pulsations, which varies significantly between consecutive data reduction iterations.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That the observed variation in pulsation significance across repeated reductions is caused solely by the documented randomisation step in XMM-SAS rather than by other unexamined aspects of the data or analysis pipeline.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"A soft-spectrum PULX candidate is reported in Cen A but XMM-SAS randomisation during data reduction renders the marginal 1.27 Hz pulsation detection unreliable across repeated reductions.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Randomisation during XMM-Newton data reduction introduces considerable uncertainty in confirming marginal pulsations from a new ultraluminous X-ray source candidate in Centaurus A.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"c59474d135fd8bca119e4ef86d638428886460f75dd110267da09bc65ff76105"},"source":{"id":"2605.15137","kind":"arxiv","version":1},"verdict":{"id":"d47ef062-8386-4e45-ae73-baf6def58bf4","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-15T03:03:51.499449Z","strongest_claim":"the intrinsic randomisation employed by XMM-Newton's Science Analysis Software, XMM-SAS, during the data reduction procedure introduces considerable uncertainty in the strength of our marginal pulsations, which varies significantly between consecutive data reduction iterations.","one_line_summary":"A soft-spectrum PULX candidate is reported in Cen A but XMM-SAS randomisation during data reduction renders the marginal 1.27 Hz pulsation detection unreliable across repeated reductions.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That the observed variation in pulsation significance across repeated reductions is caused solely by the documented randomisation step in XMM-SAS rather than by other unexamined aspects of the data or analysis pipeline.","pith_extraction_headline":"Randomisation during XMM-Newton data reduction introduces considerable uncertainty in confirming marginal pulsations from a new ultraluminous X-ray source candidate in Centaurus A."},"references":{"count":99,"sample":[{"doi":"","year":2018,"title":"Bachetti M., 2018, HENDRICS: High ENergy Data Reduction Interface from the Command Shell , Astrophysics Source Code Library, record ascl:1805.019","work_id":"55b0e83d-24e6-44e1-b52c-21153e7d7800","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2004,"title":"G., Egret D., eds, Astronomical Society of the Pacific Conference Series Vol","work_id":"96d30c22-62ec-4f7d-9b4e-668793ce5ee3","ref_index":24,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":1973,"title":"Shakura N. I., Sunyaev R. A., 1973, , https://ui.adsabs.harvard.edu/abs/1973A&A....24..337S 24, 337","work_id":"e2ae7be5-e980-4b2c-9a0a-2e21f7a70221","ref_index":63,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2025,"title":"XMM-Newton-SOC 2025, Users Guide to the XMM-Newton Science Analysis System, Issue 19.0. ESA, https://xmm-tools.cosmos.esa.int/external/xmm_user_support/documentation/sas_usg/USG/","work_id":"84d28c3a-399f-4e08-9180-c75b163cc2dd","ref_index":80,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"10.1086/307356","year":null,"title":"The Nature of Accreting Black Holes in Nearby Galaxy Nuclei","work_id":"d080f276-1e27-4c3a-92ae-d3ec608d93fb","ref_index":83,"cited_arxiv_id":"astro-ph/9901023","is_internal_anchor":true}],"resolved_work":99,"snapshot_sha256":"9df4c882acf9ee280fe63b362eb4b8d32621fe69a4f742639f7b42ec41b26ad6","internal_anchors":46},"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"}