{"paper":{"title":"X-ray spectral and optical properties of a ULX in NGC 4258 (M106)","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"Aysun Akyuz, Hasan Avdan, Inci Akkaya Oralhan, Nazim Aksaker, Senay Avdan, Solen Balman","submitted_at":"2016-07-11T10:02:09Z","abstract_excerpt":"We study the X-ray and optical properties of the ultraluminous X-ray source (ULX) X-6 in the nearby galaxy NGC 4258 (M106) based on the archival {\\it XMM-Newton}, {\\it Chandra}, {\\it Swift}, and {\\it Hubble Space Telescope} ({\\it HST}) observations. The source has a peak luminosity of $L_{\\mathrm{X}} \\sim 2 \\times 10^{39}$ erg s$^{-1}$ in the {\\it XMM-Newton} observation of 2004 June. Consideration of the hardness ratios and spectral model parameters shows that the source seems to exhibit possible spectral variations throughout the X-ray observations. In the images from the {\\it HST}/Advanced "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1607.02881","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"}