1. Michael Baker Using Time Dependent Methods for Neutrino Point Source Searches with IceCube Michael Baker January 15, 2009

2. Michael Baker Outline Cosmic Rays Astrophysical Neutrino Production IceCube Neutrino Observatory IC-22 Point Source Results Time-Dependent Analyses -- Hotspot -- Microquasars -- Multi Wavelength Flare Search

3. Michael Baker Cosmic rays are highly energetic particles, mainly protons, which come from outer space and collide with the atmosphere. The energy of cosmic rays exhibits a broken power-law spectrum.

4. Michael Baker Fermi Acceleration - Each time a particle crosses a shock it gains energy - Regardless of which direction the particle encounters the shock - Results in approximately an E^-2 energy spectrum Shock UpstreamDownstream What do we think accelerates Cosmic Rays?

5. Michael Baker “Below the knee” Protons will be confined to the galaxy for > 10^6 years The flux of cosmic rays at these energies is about 0.1 of the energy believed to be released by supernovae in the Milky Way “The Ankle” Above ~1PeV, protons will not be confined to our galaxy, so we need to find new sources. AGN? GRB?

6. Michael Baker Neutrino Production 1 : 2 : 0 1 : 1 : 1 (after oscillations)‏ High energy particles can interact with nearby matter Neglecting absorption, the flux of gamma rays from πº and neutrinos are proportional

7. Michael Baker Astronomy with Neutrinos Charged particles are deflected by magnetic fields in space, so they don't point back to their source. High Energy photons can be absorbed on the way from the source. However, neutrinos will give us a line of sight directly back to the source and aren't attenuated. The problem is that they are hard to detect once they get to Earth, so we need a big detector

8. Michael Baker Source Candidates In a nutshell, our candidate sources are anything that could accelerate particles to very high energies... ← Supernova remnants Active Galaxies -> Microquasars ->

9. Michael Baker Microquasars Compact object in a binary system with a star. The compact object will pull off matter from its companion, forming an accretion disk. Microquasar LS I +61 303 exhibits periodicity in all photon wavebands Is there a periodicity in neutrino emission?

10. Michael Baker Hess has seen TeV gamma emission from LS 5039 --Evidence of πº decay? If inelastic pp collisions make πº we also expect charged pion production in equal proportions Ls I +61 303 has also been observed to be periodic in >400 MeV photons from MAGIC

11. Michael Baker AGN and microquasars have the same underlying principle powering them Difference is a matter of scale of the jet

12. Michael Baker Marscher 2008 Model of AGN acceleration The matter distribution in AGN jets is clumpy and can be followed by radio interferometers

13. Michael Baker WIYN 0.9 inch optical telescope (Add lightcurve from something)‏

14. Michael Baker Both the Swift BAT and All Sky Monitor on XTE use a coded mask to get a wide field of view, so they scan the entire sky several times a day.

15. Michael Baker LAT first Skymap Fermi/GLAST Recently launched Fermi LAT has a 1 steradian FOV constantly scanning the sky for photons in the 100 MeV to 300 GeV energy range

16. Michael Baker Whipple telescope: Imaging Atmospheric Cherenkov Telescope Detects air showers from 100 GeV – 10 TeV photons

17. Michael Baker Multiwavelength measurements of Mrk 421

18. Michael Baker Neutrinos can create a lepton via charged current interactions, or an energetic shower by a neutral current interaction. Neutrino Detection Reno 2004

19. Michael Baker Distorted from plane wave by scattering θ c = 41º  Ĉerenkov Light Moving charged particles disturb local matter Light emitted interferes constructively to form a cone if v > c/n Ice n=1.31

20. NESTOR Pylos, Greece ANTARES La-Seyne-sur-Mer, France BAIKAL Russia DUMAND Hawaii (cancelled 1995)‏ NEMO Catania, Italy IceCube/AMANDA, South Pole, Antarctica Cerenkov Neutrino Detectors

21. 21 Amundsen-Scott South Pole station South Pole Dome Summer camp AMANDA road to work 1500 m 2000 m [not to scale]

22. Michael Baker The goal is to have a cubic km of ice underneath the South Pole instrumented with photo-multipliers. Currently 5x strings in-ice, and the new season of drilling is under way.

23. Michael Baker IceCube Construction

24. Michael Baker DOM – Digital Optical Module 10-Inch Hamamatsu PMT Main board Digitize waveform: 300 MHz for 400 ns 40 MHz for 6.4 μs Flasher board with 12 LEDs separate high voltage Time resolution: 2ns

25. Michael Baker

26. We only have good angular resolution with muons, so use a track to find a best fit for our reconstruction. We have the Pandel function to describe the probability of a photon arriving at a certain time at a certain distance from its production. The likelihood is the product of these probabilities. Iterate over all the hit DOMs and we minimize the negative log likelihood for the track. Use the most probable track, and fit a paraboloid to the shape of the likelihood space to get the angular resolution of the track.

27. Michael Baker Simulated events let us know if our reconstructed angular resolution is a good measure of the uncertainty in the track direction.

28. Michael Baker The detector's stability is especially important for time dependent searches, so here we have the event rates at Level 3 processing for IC22 data. Here we still have 11 million events, so it is dominated by mis-reconstructed background, which has a strong seasonal variation. We start with a random sample of these as random background times for the time dependent analyses Rate Stability Studies

29. Michael Baker IC22 Point Source Results Hottest spot found at r.a. 153, dec. +11 est. nSrcEvents = 7.7 est. gamma = 1.65 est. pre-trial p-value: -log10(p): 6.14 (4.8 sigma)‏ If it's a steady source, we can confirm it in subsequent years of data Concern that it could be due to a one-time occurrence.

30. Michael Baker Time Dependent Analysis of the Hotspot Time-Integrated likelihood factors Time-Dependent likelihood factors

31. Michael Baker Hotspot Analysis – Setup and Null Hypothesis Identified the events near the spot as interesting Still blind to timing information, so we can get an independent value Fix the position and energy of the events, and simulate signal by clustering events in time.

32. Michael Baker Hotspot Analysis – Discovery Potentials I performed tests with and without using the energy weights to fit a Gaussian with best-fit mean and sigma to describe a flare Use events which have S/B > 1 at the hotspot location

33. Michael Baker Hotspot Analysis – Results p-value ~ 0.5 p-value ~ 0.3 Neither analysis finds any significant clustering of events in time

34. Michael Baker Microquasar method For the microquasar study, we take the same idea as the hot spot and look for a Gaussian from the events' time modulo the period of the particular object.

35. Michael Baker Discovery Potentials 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. Wider than that and the added degrees of freedom make the time-dependent search less powerful.

36. Michael Baker Microquasar Results The smallest p-value 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

37. Michael Baker IC-22 Flares Intro In addition to periodic sources, we are also interested in examining outbursts from transient objects. For the IC-22 run, we took notes of Astronomer's Telegram alerts for objects in our source list. We used light curves once published to define a time window for each flare.

38. Michael Baker IC-22 Flares Selection 3C 454.3 July 24-30 2007 (seen with Agile)‏ Nov. 11-21 2007 (Agile and WEBT)‏ 1ES 1959 Nov 25-28 2007 (Integral report)‏ Cygnus X1 August 8 2007 (Konus-Wind, ASM)‏ S5 0716+71 September 7-12 2007 (Agile, Radio)‏ Oct 19-28 2007 (Agile, Radio)‏

39. Michael Baker Flares Method We compared two methods -- Fix a time window, events either in or out -- Use the window to constrain the mean of a Gaussian

40. Michael Baker Flares Method and Status We find there is a range of widths of signal where the box does better, due to its fewer degrees of freedom for the fit. Still discussing the analysis, haven't yet unblinded for results

41. Michael Baker Future Prospects IC 40 flare sample Prescription for general flare analysis Other PS improvements -- mirror symmetry -- Cramer-Rao method for angular resolution

42. Michael Baker With well-sampled photon data in the future, we would like a method to define flares to single out and take a Pdf directly from that photon data. We're testing a Maximum Likelihood Blocks algorithm to see how well it takes discrete measurements to a continuous function.

43. Michael Baker To test the block method we need to simulate a satellite response and use that for the analysis. How much does the telescope sampling affect what we reconstruct?

44. Michael Baker Here are samples of different trials to simulate ASM data and their reconstructions. This will give a better sense of how well blocks are representing the Pdf, to make sure that the areas are largely in the same place.

45. Michael Baker