{
  "id": "2412.13804",
  "version": "v1",
  "published": "2024-12-18T12:52:53.000Z",
  "updated": "2024-12-18T12:52:53.000Z",
  "title": "An improved method to search for flares from point sources of ultra-high-energy photons",
  "authors": [
    "J. Stasielak",
    "N. Borodai",
    "D. Góra",
    "M. Niechciol"
  ],
  "comment": "10 pages, 6 figures, proceedings of the 28th European Cosmic Ray Symposium (ECRS 2024), Hvar, Croatia, to be published in Central European Astrophysical Bulletin",
  "categories": [
    "astro-ph.HE"
  ],
  "abstract": "Flares produced by certain classes of astrophysical objects may be sources of some ultra-high-energy particles, which, if they are photons, would group into clusters of events correlated in space and time. Identification of such clustering in cosmic-ray data would provide important evidence for possible existence of ultra-high-energy (UHE) photons and could potentially help identify their sources. We present an analysis method to search for space-time clustering of ultra-high-energy extensive air showers, namely the stacking method, which combines a time-clustering algorithm with an unbinned likelihood study. In addition, to enhance the capability to discriminate between signal (photon-initiated events) and background (hadron-initiated) events, we apply a photon tag. This involves using relevant probability distribution functions to classify each event as more likely to be either a photon or a hadron. We demonstrate that the stacking method can effectively distinguish between events initiated by photons and those initiated by hadrons (background). The number of photon events in a data sample, as well as the flare(s) duration can also be retrieved correctly. The stacking method with a photon tag requires only a few events to identify a photon flare. This method can be used to search for the cosmic ray sources and/or improve limits on the fluxes of UHE photons.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-12-18T12:52:53.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "point sources",
      "ultra-high-energy photons",
      "stacking method",
      "relevant probability distribution functions",
      "photon tag"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 10,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}