Neutrino Point Source Searches with IceCube 22 String Configuration Michael Baker, for the IceCube Collaboration University of Wisconsin, Madison APS April Meeting May 2, 2009

2 Michael Baker Introduction: IceCube 22-string configuration

3 Michael Baker Neutrinos are good messengers because they aren't absorbed or deflected (unlike photons or protons) on the way from the source Detection of astrophysical neutrinos would be a “smoking gun” for high-energy proton acceleration proving which are the sources of cosmic rays Candidate neutrino sources: AGNs, SNRs, pulsars, Microquasars, GRBs,... Backgrounds: atmospheric neutrinos (all over the sky), downgoing atmospheric muons (downgoing and upgoing too, if mis- reconstructed)‏

4 Michael Baker Likelihood ratio analysis comparing Signal to signal+background hypothesis Analysis Method Time-dependent term to look for bursts of neutrinos using MWL information or periodic emission (mqso)‏ Background Signal Energy: spectrum from sources ∼ E -2, background ∼ E -3.6 PSF

5 IC22 Point Source Analysis Characteristics Michael Baker Point Spread Function Fraction of events reconstructed within a specific angle of the true direction. Confirm point spread function with moon shadow. (See talk by L. Gladstone this session)‏ Muon Neutrino Effective Area

May Apr 5: days livetime after selecting good runs. Simple set of cuts applied to data, to select good upgoing events and reject downgoing and coincident background, including:  Quality of the reconstruction  Min Number of hits from direct muon Cherenkov light  Estimated event directional uncertainty < 3 deg  log likelihood ratio of best-fit upgoing track to best-fit downgoing track 5114 Events after cuts -- ~4700 Atmospheric nu expected. Perform point source search using:  a priori list of 28 source candidates  all sky search from -5° to +85° declination Michael Baker Overview of the IC-22 dataset

7 Michael Baker IC22 Point Source Results Lowest pretrial p-value of 28 on source list: 1ES (p=0.07, not significant after trial factors are taken into account). Hottest spot found at r.a. 153º, dec. +11º est. nSrcEvents = 7.7 est. gamma = Post-Trials p-value of the hottest spot is 1.35% (2.2 σ)‏ If spot is a steady source, we can confirm it in subsequent years of data Concern that it could be due to a one-time occurrence. paper to be submitted shortly

Discovery potential for 22 strings: ~12 E^-2 spectrum events needed for 50% 5σ detection on average Sensitivities 90% CL Binned analysis including strict energy cuts extends the FoV to the Southern sky Michael Baker Sensitivities

9 Michael Baker Time Dependent analysis of the Hotspot Neither analysis finds any significant clustering of events in time. P= 0.5 using energy, p=0.3 without. We decided to perform a test to look for a clustering of signal from the hotspot, and examined the weights with and without the energy weights. Blue is the event weights Black is the raw events Red is the best-fit gaussian

10 Michael Baker Microquasars Binary stellar systems which have evidence of a non-thermal radio jet. We assumed neutrino emission is periodic with the orbit of the system. Time Integrated Time Dependent We found that the discovery potential is better than the time- integrated analysis if the sigma of the emission is less than one fifth of the period. Tested 7 northern-hemisphere microquasars, didn't see a a significant excess. : width normalized to one period arXiv:astro-ph/ v2

11 IceCube 22 String Multiwavelength Flare Search Testing for correlation between neutrino emission and multiwavelength observations of high states in astronomical objects R F GHz S Lightcurve We chose: 3C 454.3: July and Nov ES 1959: Nov and Dec Cygnus X-1: August S : September and October Michael Baker

12 Michael Baker 5 of 7 time windows returned p-value=1 (this fraction of scrambled data gives a higher test statistic than the data)‏ Two flares give p-values of 0.02 and 0.08 S Oct ES Dec p=0.02p=0.08 nsrc=0.99 nsrc=0.76 We took samples of random p-values for all 7 time windows we looked at, and find that the product of the p-values is less in 10% of trials. Still consistent with background fluctuations. IceCube 22 String Multiwavelength Flare Search

13 Michael Baker With the IceCube 22 string dataset, we added a time- dependent hypotheses in conjunction with the point-source analysis. We tested for periodic and transient sources, and did a test for neutrino flares for the hotspot. No test returned a statistically significant result. For the IceCube 40 string dataset, we plan to look at periodic emissions from microquasars, MWL flares, and time dependencies of the hottest spots. Conclusions

14 Michael Baker Backup

15 Michael Baker Microquasar Results The smallest p-value pretrial we got for the microquasar analysis is 0.06 for SS 433, which isn't significant given we looked at 7 objects SS 433 Here are two examples of the 7 microquasars, the events are plotted in phase. Black is the # events per bin, blue the space and energy in the bin, and red is the best-fit Gaussian reconstruction. Ls I +61