SN2025cbj LAST and ZTF photometric data

Using a simple post-shock-breakout interaction model in a dense wind, we estimated the expected muon-neutrino yield for IceCube's real-time Bronze stream. Spectra of SN2025cbj obtained after the neutrino epoch show persistent narrow Balmer lines superposed on broad Lorentzian electron-scattering wings, consistent with sustained dense-CSM interaction. For the multi-messenger association, resampling simulations against the TNS catalog give a chance-coincidence probability for observing k>=1 events of p=~0.24 (and p=~0.078 against the ZTF-BTS catalog).

These values are sensitive to the size of the SNe and neutrino samples. A post-breakout interaction scenario predicts an expected N{nu}{mu}~10^-3^ events in the IceCube Bronze alert stream over 76 days per this one candidate. We discuss the implications of these numbers and possible biases that may affect these results.