IceCube and searches for astrophysical sources

Understanding cosmic acceleration mechanisms, such as jet formation in black holes, star collapses or binary mergers, and the propagation of accelerated particles in the universe is still a 'work in progress' and requires a multi-messenger approach, exploiting the complementarities across all possible probes: ultra-high energy cosmic rays (UHECR), gamma-rays and neutrinos. In this report I will summarize some of the IceCube results concerning searches for astrophysical neutrino point sources and diffuse fluxes from populations of sources widely distributed in the sky or from the interactions of protons on the cosmic microwave background producing the GZK cut-off in the cosmic ray spectrum. I will compare the results to other neutrino telescopes and to astrophysical models of neutrino production in sources. Another unresolved question concerns the nature of dark matter. Indirect searches have the opportunity to observe where it is located in the universe through the observation of secondary photons, neutrinos or antiparticles such as positrons and antiprotons. The potential for the search of neutrinos from the annihilation of WIMPs in IceCube is greatly enhanced by the addition of more compact strings, the DeepCore.