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Search Strategies for Astrophysical Neutrinos with IceCube and AMANDA Collaborations

Explore search strategies for finding astrophysical neutrinos, focusing on IceCube and AMANDA collaborations' operations and future plans. Learn about methods like binned and unbinned searches, all-sky and Galactic plane scans, and the analysis of extended regions like the Cygnus constellation. Uncover the potential of multi-point source analysis in clustering neutrino events and discover the motivation behind studying extended regions in the galactic plane. Delve into the detailed analysis of the Cygnus region using data from IceCube and AMANDA, aiming to uncover potential astrophysical sources of neutrinos. Furthermore, understand the significance of extended source searches and potential discoveries in the field of neutrino astronomy.

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Search Strategies for Astrophysical Neutrinos with IceCube and AMANDA Collaborations

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  1. Strategies in the search for astrophysical neutrinos Yolanda Sestayo, MPI-k Heidelberg for the IceCube collaboration VLVνT 09, Athens

  2. AMANDA/IceCube searches for extraterrestrial neutrinos • AMANDA: E > 100 GeV • IceCube: E > ~ TeV Energy Range AMANDA: operation period between 1997-2009 (Abbasi et al. 2009) IceCube • 2006-2007: 9 strings (Finley et al. 2008ICRC) • 2007-2008: 22 strings (Abbasi et al. 2009) • 2008-2009: 40 strings (data is being analyzed) • 2009-2010: 59 strings (taking data) 2006-2007: AMANDA DAQ integrated into IceCube DAQ (Gross et al. 2008ICRC) IceCube + AMANDA • IC22 strings + AMANDA (Portello-Roucelle et al. 2009ICRC) • IC40 strings + AMANDA (data is being analyzed) FUTURE:IceCube + DeepCore

  3. POINT SOURCE SEARCH STRATEGIES • Binned method: samples the sky in angular bins centered in a grid of points of 0.25o x 0.25o. • Unbinned method: test the hypothesis of signal neutrinos from single point sources located at the positions of the grid. Constructs the likelihood assuming a signal pdf following a gaussian plus an energy term. • Steady sources: No time dependence expected • (supernova remnants, pulsar wind nebula, etc) • Time-varying sources: Analysis optimized by a priori information on the variability • (micro-qso, blazars, etc)

  4. SEARCH METHODS: ALL-SKY SEARCH Unbinned analysis ~TeV < E < few PeV AMANDA 3.8 yrs 100 GeV < E < few PeV IceCube 22 strings Unbinned analysis

  5. SEARCH METHODS: GALACTIC PLANE SCAN Combined IceCube 22 strings + AMANDA analysis 100 GeV < E < few PeV Galactic latitude Unbinned analysis Galactic longitude

  6. SEARCH METHODS: ALL-SKY SEARCH • Best way to find neutrino sources without a known counterpart Large statistical penalties (trial factors) All-sky surveys are based on a point-source search over a grid covering all the sky only sensitive to emission within the model PSF Promising sources are studied in separate analysis Need to develop a method to study extended (non-point source) regions

  7. Galactic Accelerators • Galactic accelerators always associated with regions of massive star formation: • Supernova remnants • Pulsar wind nebula • Micro-qso • Massive stellar winds Cas A, SNR Crab, PWN Microqso Wolf-Rayet star

  8. SEARCH STRATEGIES: EXTENDED REGIONS Cygnus: 850 < l < 700 00 • Angular resolution IceCube 80 strings ~ 1o • IC22 ~ 2o • IceCube extended source: • rather an extended region, comprising several • point sources 900 2700 SUN Motivation: extended regions in the galactic plane Superposition of sources at different distances comprising a relatively large area in the sky

  9. Cygnus Region Cygnus There is the compelling need to develop a method which can be applied efficiently to extended regions such as Cygnus! COMPTEL 1.809 MeV line Pluschke et al. 2001 Beacom & Kistler 2007 Abdo et al. 2007

  10. EXTENDED REGIONS: MULTI POINT SOURCE ANALYSIS (MPS) Cygnus region Cygnus region • GOALS: • To have a method which: • Is model independent • - number of sources/clusters unknown • - shape and location of emission unknown • (clustered + diffuse emission) • 2) Takes advantage of the full signal content • - sensitive to weaker neutrino PSs than • std point source analyses if Nsrc > 1 Astrophysical neutrinos in the region increase the clustering of events Signal events (from astrophysical sources) Background events (atmospheric neutrinos) SIGNAL CASE RANDOM CASE

  11. EXTENDED REGIONS: MULTI POINT SOURCE ANALYSIS (MPS) Cygnus region 2-point correlation function: Quantifies clustering of events as function of the angular separation MPS counts pairs of events as function of the angular distance between the events in the pair Pair of events ≡ (event inside, event) Clustering of events increases the number of close pairs • MPS: • 2-point correlation function of the candidate neutrino events, where: • Primaries: events inside the region • Secondaries: all events

  12. EXTENDED REGIONS: MULTI POINT SOURCE ANALYSIS (MPS) MPS focuses on small scale clustering (close pairs)

  13. EXTENDED REGIONS: MULTI POINT SOURCE ANALYSIS (MPS) Cygnus region 2-point binned sampling of the region at the locations of each of the neutrino events. MPS treats every event inside the region as a point source Single-point binned sampling 2-point binned sampling Relative frequency Relative frequency Companions per bin

  14. ANALYSIS OF THE CYGNUS REGION USING IC22+AMANDA 72o < l < 83o, -3o < b < 4o • Selection of the region: • Most intense γ-ray emission • 8 OB associations 72o < l < 83o, -3o < b < 4o

  15. DISCOVERY POTENTIAL Diffuse limit: MPS = binned search Diffuse limit All-sky search With IC22+AMANDA angular resolution we reach the diffuse limit with more than 4 point sources inside the region

  16. RESULTS PRELIMINARY PRELIMINARY UPPER LIMITS Flux Upper Limit for the whole region of 11o x 7o: 7.29x10-11 TeV cm-2s-1 (90% CL) RESULTS COMPATIBLE WITH A BACKGROUND FLUCTUATION

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