{"paper":{"title":"The X-ray Variability of the Ultraluminous X-ray Sources in the NGC 4631 galaxy","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"Jianfeng Wu, Jiashun Chen, Zikun Lin","submitted_at":"2026-07-07T11:33:19Z","abstract_excerpt":"We perform a systematic study on the long-term X-ray variability for the five ultraluminous X-ray sources (ULXs) in the NGC 4631 galaxy (X1-X5), using Chandra, XMM-Newton, and Swift observations covering a 24-year span. Light curves for the five ULXs are presented, while X-ray spectra were modeled for observations with sufficient counts. The normalized excess variance and structure function are utilized to study the X-ray variability behavior of the ULXs. The normalized excess variance is anti-correlated with average X-ray luminosity for three ULXs, indicating that objects with higher average "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2607.06156","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/2607.06156/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"}