Theoretical astrophysics and plasma physics at RPC

Abstract:

Ultraluminous infrared galaxies (ULIRGs) have infrared luminosities LIR ≥ 1012L⊙, making them the most luminous objects in the infrared sky. These dusty objects are generally powered by starbursts with star formation rates that exceed 100 M⊙ yr−1, possibly combined with a contribution from an active galactic nucleus. Such environments make ULIRGs plausible sources of astrophysical high-energy neutrinos, which can be observed by the IceCube Neutrino Observatory at the South Pole. We present a stacking search for high-energy neutrinos from a representative sample of 75 ULIRGs with redshift z ≤ 0.13 using 7.5 yr of IceCube data. The results are consistent with a background-only observation, yielding upper limits on the neutrino flux from these 75 ULIRGs. For an unbroken E−2.5 power-law spectrum, we report an upper limit on the stacked flux ${{\rm{\Phi }}}_{{\nu }_{\mu }+{\bar{\nu }}_{\mu }}^{90 \% }=3.24\times {10}^{-14}\,{\mathrm{TeV}}^{-1}\,{\mathrm{cm}}^{-2}\,{{\rm{s}}}^{-1}\,{(E/10\,\mathrm{TeV})}^{-2.5}$ at 90% confidence level. In addition, we constrain the contribution of the ULIRG source population to the observed diffuse astrophysical neutrino flux as well as model predictions.