Speaker
Description
The astrophysical origin of high-energy neutrinos detected by IceCube remains an open question. Explosive transients, such as supernovae and tidal disruption events, have been proposed as source candidates, but their contribution has not yet been firmly established. Identifying such transients as neutrino sources requires rapid and sensitive electromagnetic follow-up observations. However, most optical follow-up observations to date have relied on 1 m-class telescopes, whose sensitivity is often insufficient to detect transients at the expected distances (redshift z < 0.5-1.0). To overcome this issue, we focus on IceCube neutrino "multiplet" events, in which multiple neutrinos are detected from a consistent direction within a limited time window. Such events provide a valuable opportunity to search for nearby sources (z < 0.1-0.3). Using archival data from the Zwicky Transient Facility (ZTF), we performed a search for optical counterparts to an IceCube multiplet event. No convincing counterpart was identified, but the search allowed us to place stringent constraints on optical transients. I will discuss the lessons learned from this search, with particular emphasis on the importance of blind analysis, and robust estimates of background contamination and detection efficiency.
