Speaker
Description
The majority of multi-messenger observations that combine X-rays and neutrinos to target transient objects have been restricted to reporting flux upper limits, yielding minimal physical insights. We hereby propose a novel analytical method that integrates a generic cosmic-ray and neutrino emission model with unspecified physical parameters and a novel data analysis approach, which enables the determination of the parameter space that a cosmic-ray origin must meet. We employed this method to conduct searches for X-ray source counterparts of neutrinos from the IceCube experiment. The X-ray all-sky monitor MAXI and the X-ray space telescope Einstein Probe-WXT were utilized in this study. We show that representative soft X-ray transients, including low-luminosity gamma-ray bursts and jetted TDEs, are not significant contributors to high-energy neutrino emission. In addition, the unified model in which ultra-high-energy cosmic rays and high-energy neutrinos share a common transient source origin is stringently constrained, thereby nearly ruling out any X-ray transients with the jet bulk Lorentz factor larger than 4. The potential for further developing this analytical method and applying it to steady sources, such as active galactic nuclei, is also discussed.