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@ARTICLE{Peil:644519,
      author       = {Peñil, Pablo and Torres-Albà, Nuria and Rico, Alba and
                      Ajello, Marco and Buson, Sara and Adhikari, Sagar},
      title        = {{D}istortions in periodicity analysis of blazars: the
                      impact of flares},
      journal      = {Monthly notices of the Royal Astronomical Society},
      volume       = {539},
      number       = {2},
      issn         = {0035-8711},
      address      = {Oxford},
      publisher    = {Oxford Univ. Press},
      reportid     = {PUBDB-2026-00378, arXiv:2504.05092},
      pages        = {993 - 1014},
      year         = {2025},
      note         = {2 tables, 8 figures},
      abstract     = {Blazars, a unique class of active galactic nuclei, exhibit
                      highly variable emission across the electromagnetic
                      spectrum. This variability frequently manifests as intense
                      flaring events, sparking an ongoing debate in recent
                      literature about whether these flares exhibit periodic
                      behaviour in certain sources. However, many blazars also
                      show clear signs of stochastic, uncorrelated flares that do
                      not follow a regular pattern. This paper explores how the
                      presence of one such of these stochastic flares can distort
                      an intrinsically periodic pattern of emission in blazars.
                      Our results demonstrate that, depending on the specific
                      circumstances, the deviations in significance and periods
                      can exceed 100 per cent. Sometimes, these deviations can be
                      so severe that they eliminate any evidence of a periodic
                      pattern. These findings highlight the dramatic impact that
                      flares can have on periodicity searches. To confront this
                      challenge, we propose an innovative approach, the Singular
                      Spectrum Analysis method, which appears more robust against
                      the effects of flares. As an alternative solution, we also
                      propose the sigma clipping technique to mitigate the impact
                      of flares. This framework offers a valuable foundation for
                      analysing periodicity in similar astrophysical sources that
                      are also subject to stochastic flaring events.},
      keywords     = {BL Lacertae objects: general (autogen) / methods: data
                      analysis (autogen) / galaxies: active (autogen)},
      cin          = {$Z_GA$},
      ddc          = {520},
      cid          = {$I:(DE-H253)Z_GA-20210408$},
      pnm          = {613 - Matter and Radiation from the Universe (POF4-613) /
                      DFG project G:(GEPRIS)443220636 - FOR 5195: Relativistische
                      Jets in Aktiven Galaxien (443220636)},
      pid          = {G:(DE-HGF)POF4-613 / G:(GEPRIS)443220636},
      experiment   = {EXP:(DE-MLZ)NOSPEC-20140101},
      typ          = {PUB:(DE-HGF)16},
      eprint       = {2504.05092},
      howpublished = {arXiv:2504.05092},
      archivePrefix = {arXiv},
      SLACcitation = {$\%\%CITATION$ = $arXiv:2504.05092;\%\%$},
      doi          = {10.1093/mnras/staf482},
      url          = {https://bib-pubdb1.desy.de/record/644519},
}