1. The IceCube Neutrino Observatory is a cubic kilometer detector currently under construction at the geographic South Pole. We will give an overview of searches for neutrino point-sources and outline how we utilize data from Fermi for neutrino flare searches. Neutrino Point Source Searches with IceCube M. Baker, J. Dumm, J.A. Aguilar, C. Finley and T. Montaruli for the IceCube Collaboration mfbaker@icecube.wisc.edu IceTop InIce Air shower detector threshold ~ 300 TeV 86 Strings, 60 Optical Modules Per String AMANDA 19 Strings 677 Modules Total The IceCube Detector IceCube is a high-energy neutrino observatory currently under construction at the geographic South Pole. The full detector will be composed of 86 strings of 60 Digital Optical Modules (DOMs) each, deployed between 1500 and 2500m below the glacier surface. A six string Deep Core with higher quantum efficiency photomultipliers and closer DOM spacing in the lower detector will enhance sensitivity to low energy neutrinos. Muons passing through the detector emit Cherenkov light allowing reconstruction with <1º angular resolution in the full detector. Point Source Search with the 40 String Configuration Detector Threshold Time-Dependent Point Source Search with Fermi LAT Lightcurves We are interested in using a multi-messenger approach to search for neutrino sources. Fermi is particularly interesting for this approach, since neutral pions decay to gamma rays and charged pions to neutrinos and muons. In high energy pp and pγ interactions we would expect roughly equal numbers of charged and neutral pions will be created. Information from high-energy astronomy experiments can be used to search for neutrinos in coincidence with high photon flux states, enhancing the potential for source discovery and over a time- integrated search. Candidate sources such as blazars exhibit variability on the timescale of hours, and the comprehensive sky coverage of Fermi opens up new approaches for our analyses. Blazars flares are interesting since they correspond to clumps of material moving into the jet, possibly meaning more inteactions. We have developed a method of incorporating this multi-messenger information into the maximum likelihood method, using the Maximum Likelihood Block [4][5] method to denoise 1-day binned LAT light curves. We explored the possibility of leaving the time lag and threshold for emission as free parameters in the likelihood fit. This allows us to simultaneously search over a wide range of these parameters, keeping sensitivity to a wide range of physical models without substantially hurting the sensitivity to any particular model. Using this new information dramatically lowers the amount of signal required for discovery compared to the time-integrated search in the case where neutrino emission occurs during flares. An example of the Fermi LAT lightcurve, the Maximum Likelihood Block reconstruction and threshold parameter for PKS1510-089. On the right is the shape of the time-dependent Pdf for this particular threshold. The discovery of a source of high-energy astrophysical neutrinos would be evidence of hadronic acceleration, and give insight on the origins of cosmic rays. To this end we have six months of 40-string data (July to December 2008) unblinded. The event selection has been pushed to a high-energy sample in the southern hemisphere, where the back- ground for astrophysical neutrinos is from down-going atmospheric muons, as opposed to the north where the background is from atmospheric neutrinos. We find a spot with equal or greater significance than the most significant spot on this skymap in 61% of trials with scrambled Right Ascension [3]. We also tested a list of 39 a priori sources including the hottest spot from the IceCube 22-string all-sky analysis, we also found that 62% of scrambled trials have a source with higher significance than the most significant source in data. The livetime of the final 40-string configuration of IceCube will be approximately 390 days. Pretrial significance map (celestial coordinates) of the 6-month sample of 40-string configuration data. The data sample is 17777 events, of which 6797 are up-going neutrino candidates from the northern hemisphere. The black line marks the Galactic Plane. Above are E^-2 flux sensitivity estimates for different IceCube detector configurations, as well as the ANATRES detector. Below are curves for the fraction of simulated events reconstructed within an angle of the true track for different energy ranges and configurations of the IceCube detector. We use the angular and energy distribution of events as information to characterize the signal with respect to the background using a maximum- likelihood ratio method [1]. In the analysis of the 22- string data [2] we use the number of hit DOMs in an event as an energy estimator, while for the 40-string configuration we use an energy estimator based on the photon density along the muon track [3]. The analysis method returns a best-fit number of signal events and spectral index.Method Where σ is the angular uncertainty of the track direction, x i and x s the neutrino and source direction,respectively, E i the energy parameter of the event and γ the fit energy spectrum and T i is the time-dependent source term developed in this work. In the northern sky, the background for astrophysical neutrino searches are atmospheric neutrinos produced by cosmic ray air showers. In the southern sky the background is atmospheric muons, whose rate follow temperature variations at the South Pole. These backgrounds have known distributions in time, so if an astrophysical neutrino source has time- dependent behavior, that information can be used to enhance the potential for discovery. Below we show the 1-day binned distribution of upgoing neutrino candidates from the 22-string detector. Time-Dependent Motivation References Above we use simulated neutrino detector data to show the improvement on the average number of E^-2 spectrum events required to achieve a 5-sigma significance in 50% of trials. We plot this as a function of the threshold emission of the PKS1510-089 lightcurve (above far right) and as the amount of time above emission threshold. Sources we plan to use Fermi LAT lightcurves for analysis include: 3C279 3C66A/B 3C454.3 J123939+044409 PKS 0454-234 PKS 1454-354 PKS 1502+106 PKS 1510-089 PRELIMINARY [1] Braun. J. et al., Astropart. Phys. 29, 299 (2008). [2] Abbasi, R. et al.,.arXiv:0905.2253. [3] Dumm, J. et al., “All-Sky Point-Source Search with 40 Strings of IceCube” ICRC Lodz 2009. Abstract 0653 [4] Scargle, J. D. 1998, ApJ, 504, 405 (S98) [5] Resconi, E. et al,. A&A 502, 499-504 (2009)