The ultra-high energy cosmic neutrinos, which usually perambulate gigantic scales in the extragalactic universe, are expected to play a pivotal role in determining the origin of cosmic rays as well as probing new physics extending even up to the Planck scale. This epitomizes the selling point of several currently running or planned neutrino telescopes. These neutrinos can have magnetic moment owing to quantum loop corrections which can lead to the phenomenon of spin flavor oscillation rendering sterile neutrinos.
Using the current upper bounds on the neutrino magnetic moment, in Phys. Lett. B 839, 137791 (2023), we show that the flux of cosmic neutrinos will get reduced by half if they traverse a few megaparsecs through the intergalactic magnetic field in the range of micro to nano-Gauss. However, achieving a reduction in flux is not attainable for neutrinos generated near the center of the Milky Way, as the distances they cover are not extensive enough to satisfy the condition for the averaging out of probabilities. Moreover, one can safely neglect the effect of neutrino magnetic moment if the current upper bound is improved by a few orders of magnitude even if the neutrinos embark on epic journeys spanning the entire size of the visible universe.