NBIA Seminar: Shin’ichiro Ando

Origin of the high-energy neutrinos detected with IceCube is still to be uncovered. Promising source populations are considered to be blazars, star-forming and starburst galaxies, radio galaxies, etc. After going over these potential sources, I will discuss two approaches to constrain the origin by using the anisotropies of the current/future data. (1) Since a power-law flux distribution is a generic feature of any astrophysical sources, one can constrain the flux of the brightest neutrino source using its variance (i.e., Poisson angular power spectrum). This will constrain less abundant but brighter source populations such as blazars. (2) If the neutrinos are produced by pp interactions, one can also use the diffuse gamma-ray background to constrain neutrino sources. I will show that recent measurement of cross correlations between the gamma-ray background and nearby galaxy catalogs is very powerful in constraining contributions from spectrally soft sources with mild redshift evolution.