{
  "abstract": "Recurrent structure in supernova (SN) light curves may reveal physical clocks associated with central-engine dynamics, binary orbital motion, or interaction with structured circumstellar material (CSM). We present a multiband photometric reanalysis of the nearby hydrogen-poor superluminous SN (SLSN-I) 2018bsz (z=0.0267), using Swift/UVOT and GROND observations spanning approximately 110 rest-frame days after maximum light. After independently modelling and subtracting the smooth decline in each band, Generalized Lomb-Scargle periodograms reveal recurrent residual variations at broadly consistent phases across ten bands from u to Ks. The strongest individual-band detections, in the g, r, i, z, and J bands, yield periods of 31.5-31.8 days, while the joint multiband analysis gives a rest-frame period of P=31.61 (+/-0.03) days. The modulation is traced over approximately three cycles and is therefore described as quasi-periodic. The signal is robust to the adopted detrending procedure, while comparison-star and lunar-cycle tests disfavour an observational systematic. The modulation is broadly phase-coherent from the optical to the near-infrared, but its amplitude increases towards shorter wavelengths; lower-significance bands also show possible wavelength-dependent shifts in the best-fitting period. The present observations do not uniquely determine the physical origin. Lense-Thirring precession, interaction with CSM structured before the explosion, and post-SN interaction with a surviving companion remain possible. SN 2018bsz provides one of the clearest examples of coherent, month-scale photometric modulation in an SLSN-I.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.19984",
  "author_total": 11,
  "authors": [
    {
      "name": "Aiswarya Sankar. K"
    },
    {
      "name": "Ting-Wan Chen"
    },
    {
      "name": "Seán J. Brennan"
    },
    {
      "name": "Morgan Fraser"
    },
    {
      "name": "Keiichi Maeda"
    },
    {
      "name": "Thomas Moore"
    },
    {
      "name": "Sheng Yang"
    },
    {
      "name": "Amar Aryan"
    },
    {
      "name": "Dietrich Baade"
    },
    {
      "name": "Ping Chen"
    },
    {
      "name": "Chow-Choong Ngeow"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ayp3qpmgv2499.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.19984",
  "fulltext_url": null,
  "id": "ayp3qpmgv2499",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.19984",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.HE"
    ],
    [
      "openalex",
      "3103|Gamma-ray bursts and supernovae"
    ]
  ],
  "openalex": "W7213594834",
  "pdf_url": "https://arxiv.org/pdf/2609.19984",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ayp3qpmgv2499.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:19Z",
      "native_id": "2609.19984",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.19984"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    }
  ],
  "title": "A 32-day Quasi-periodic Modulation in the Post-peak Light Curve of the Superluminous Supernova SN 2018bsz",
  "title_text": "A 32-day Quasi-periodic Modulation in the Post-peak Light Curve of the Superluminous Supernova SN 2018bsz",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:19Z",
  "url": "https://research.draconitic.com/paper/ayp3qpmgv2499",
  "venue": "arXiv",
  "versions": []
}