Recent Results of Point Source Searches with the IceCube Neutrino Telescope Lake Louise Winter Institute 2009 Erik Strahler University of Wisconsin-Madison For the IceCube Collaboration 2/17/2009

Outline Motivation Astrophysical Neutrinos Detection Steady Sources Transients Outlook

Why look for Neutrinos? Neutrinos from GRBs

The Cosmic Ray Connection Sources of the highest energy cosmic rays are unknown. Need either very large B fields or spatial extent in order for acceleration mechanisms to work. GRBs are one of the few source candidates.

Astrophysical Neutrinos Assume hadronic acceleration with equal energy injection as electrons Protons interact with Syncrotron and IC photons Typical energy spectrum: E-2

Neutrino Detection in IceCube -Cherenkov radiation emitted by muon -Optical sensors record arrival time of photons for track reconstruction

Detector IceTop 19 strings 677 optical modules Operated 2000-2007 Now integrated with IceCube 59 dfasdfsadf

Reconstruction Tracks / Cascades reconstructed based on Cherenkov photon arrival times and intensities. 1.5 – 2.5 degrees. ~x2 in energy .3-.4 in log(E) vs. .1-.2 in log(E) Better Pointing Resolution Better Energy Resolution Better Background Rejection

IceCube Analyses Cosmic Ray Composition Supernovae Neutrinos Atmospheric Neutrinos Indirect Dark Matter Searches Diffuse Astrophysical Neutrinos GZK Neutrinos Time Integrated Point Sources Transient Point Sources

Detection Challenges Down-going muons from CR showers misreconstructed as up-going Particularly coincident muons from independent showers Must reject with tight quality cuts Up-going atmospheric neutrinos from CR showers on other side of Earth Softer energy spectrum than signal Isotropically distributed Downgoing Muons Atmospheric Neutrinos Signal Neutrinos Signal Neutrinos Atmospheric Neutrinos Downgoing Muons

Shadow of the Moon Important verification of timing and angular reconstruction Structure can reveal anisotropies in resolution

Background PDF from data Likelihood Method Partial PDF: Likelihood function: Null hypothesis: Likelihood Ratio: Background PDF from data Maximize LLH ratio by varying ns

Point Source Sensitivity

Point Source Results Hottest spot found at r.a. 153º , dec. 11º preliminary Hottest spot found at r.a. 153º , dec. 11º est. nSrcEvents = 7.7 est. gamma = 1.65 est. pre-trial p-value: -log10(p): 6.14 (4.8 sigma) Post-trials p-value of analysis is ~ 1.34% (2.2 sigma) ...

Fraction of Experiments Multiples of Predicted Flux GRB Search Fraction of Experiments Multiples of Predicted Flux Use measured quantities of all GRBs to model the neutrino emission Discovery Potential: 2.6 * Prediction

GRB Result Value of the likelihood ratio test is consistant with the null hypothesis Preliminary Limit: 4.6 * Predicted Flux Measured

UHE Point Source Sensitivity

UHE Point Source Results preliminary Coordinates: Dec. 1.00°, RA 103.5° (6.9 h) Bin content: 8 events for 1.19 expected (109 in dec. band) P-value: 2.9*10-5 (pre-trial prob.), 0.345 post trial equivalent sigma: 4.02316 (pre-trial), insignificant post-trial

Conclusions and Outlook No astrophysical neutrinos yet, but sensitivities improving rapidly 40 string IceCube configuration online from April 2008 Already as large as full detector on long axis Data run complete in April 2009 19 additional strings deployed this season. Fermi Satellite adds significant observation opportunities for GRBs 80 string IceCube only a few years away. Expect factor 6-10 increase in sensitivity Hopefully see signal neutrinos very soon!