Ultra-luminous infrared galaxies (ULIRGs) have infrared luminosities $L_{ \mathrm{ IR}} \geq 10^{ 12} L_{ \odot}$, making them the most luminous objects in the infrared sky. These dusty objects are generally powered by starbursts with star-formation rates that exceed $100~ M_{ \odot}~ \mathrm{ yr}^{ -1}$, 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 $z \leq 0.13$ using 7.5 years 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 $\Phi_{ \nu_\mu + \bar{ \nu}_\mu}^{ 90\%} = 3.24 \times 10^{ -14}~ \mathrm{ TeV^{ -1}~ cm^{ -2}~ s^{ -1}}~ (E/10~ \mathrm{ TeV})^{ -2.5}$ 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.
Categories: astro-ph.HE