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Multi-messenger approaches to search for point sources of high energy neutrinos with AMANDA/IceCube

Multi-messenger approaches to search for point sources of high energy neutrinos with AMANDA/IceCube. Elisa Bernardini DESY/Helmholtz-Gemeinschaft For the IceCube Collaboration. State of the art in the search for point sources of neutrinos. Neutrino telescopes: large field of view

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Multi-messenger approaches to search for point sources of high energy neutrinos with AMANDA/IceCube

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  1. Multi-messenger approaches to search for point sources of high energy neutrinos with AMANDA/IceCube Elisa Bernardini DESY/Helmholtz-Gemeinschaft For the IceCube Collaboration

  2. State of the art in the search for point sources of neutrinos • Neutrino telescopes: • large field of view • continuously operated AMANDA 2000-2004 Atmospheric neutrinos Elisa Bernardini

  3. Multi-messenger approach p p e 0 + n   cosmic rays + gamma-rays cosmic rays + neutrinos Explore the nature and origin of ultra-high energy cosmic rays and the mechanisms of cosmic accelerators Study the Universe beyond classical multi-wavelength observations by combining different astrophysical messengers Elisa Bernardini

  4. Search for point sources of neutrinos: start from multi-wavelength Other AGNs • Select target sources • 5 TeV Blazars • 8 GeV Blazars • 9 Microquasars and neutron star binary systems • 6 Supernovae remnants and pulsars • 2 other AGNs and 2 unidentified high energy gamma-ray sources • Source stacking: • AGNs grouped in classes of potential high energy neutrino sources • Assumption: neutrino flux is linear with luminosity TeV Blazars SNRs & Pulsars Unid. GeV Blazars Binary systems AMANDA results: more in M. Ackermann, this conference Elisa Bernardini

  5. Search for time variable sources of neutrinos Expected time correlation Idea: • Given the highly variable character of many candidate sources, is it possible to enhance the detection chance by looking for correlations with other signals? • How? • Knowing where to look and when to look Elisa Bernardini

  6. Gamma-ray input to neutrino telescope (off-line data analysis) Markarian 421, X-ray data (2000-2003) Search for coincidences with known periods of enhanced electromagnetic emission: • Periods and sources selected based on the existing multi-wavelength information Elisa Bernardini

  7. Gamma-ray input to neutrino telescope (off-line data analysis) Search for coincidences with known periods of enhanced electromagnetic emission: • Periods and sources selected based on the existing multi-wavelength information AMANDA results for 2000-2003 are compatible with atmospheric neutrinos Elisa Bernardini

  8. Gamma-ray input to neutrino telescope (off-line data analysis) Search for coincidences with known periods of enhanced electromagnetic emission: • Default assumption: close time correlation between photons and neutrinos • Multi-wavelength information is limited • Theoretical prediction on detailed time correlation are meager Elisa Bernardini

  9. Gamma-ray input to neutrino telescope (off-line data analysis) sliding window neutrino events time Search for coincidences with known periods of enhanced electromagnetic emission: Search for n flares using time-sliding windows: • Default assumption: close time correlation between photons and neutrinos • Multi-wavelength information is limited • Theoretical prediction on detailed time correlation are meager • Less model dependent • Electromagnetic “dark flares” are not excluded a-priori • Trial factor is high Elisa Bernardini

  10. Gamma-ray input to neutrino telescope (off-line data analysis) Search for coincidences with known periods of enhanced electromagnetic emission: Search for n flares using time-sliding windows: • Default assumption: close time correlation between photons and neutrinos • Multi-wavelength information is limited • Theoretical prediction on detailed time correlation are meager Galactic (20 day window) Extra-galactic (40 day window) AMANDA results for 2000-2003 are compatible with atmospheric neutrinos Elisa Bernardini

  11. Gamma-ray input to neutrino telescope (off-line data analysis) Search for coincidences with known periods of enhanced electromagnetic emission: Search for n flares using time-sliding windows: • Default assumption: close time correlation between photons and neutrinos • Multi-wavelength information is limited • Theoretical prediction on detailed time correlation are meager Whipple 1ES1959+650 E>600 GeV “Orphan flare” (MJD 52429) The IceCube Coll., 29th ICRC, Pune (2005) Elisa Bernardini

  12. Neutrino trigger to gamma-ray telescope (on-line data analysis) neutrino events time trigger window for gamma-ray observations gamma-ray flare New proposal presently under discussion within the IceCube Collaboration Idea: with the available resources and minimal impact on the observation plans, can we start developing a program of combined observations? Assumption: Correlation between high energy gamma-ray flares and enhanced neutrino emission time Elisa Bernardini

  13. Neutrino trigger to gamma-ray telescope (on-line data analysis) New proposal under development and discussion Idea: with the available resources and minimal impact on the observation plans, can we start developing a program of combined observations? • Increase cases of simultaneous observations • Help gamma-ray telescopes to catch flares that might be lost otherwise • Help discovery: better understand phenomenology of first neutrino candidate signals • Improvement only for gamma-ray sources with small duty cycle • Knowledge of rate of gamma-ray flares necessary to assign a significance to the coincidences Elisa Bernardini

  14. Target of Opportunity observations triggered by high energy neutrinos? MAGIC Could observe triggered by IceCube VERITAS Long-term gamma-ray observations H.E.S.S. CANGAROO small overlap in the visible sky IceCube could release an alert anytime a neutrino is detected from selected directions Elisa Bernardini

  15. Target sources • Confirmed GeV and TeV gamma-ray sources • Variable objects in a time scale larger than a few hours but with small duty cycle (≤ 10%) • Objects already listed in the observation plan of gamma-ray telescopes • To be discussed: best candidates to be chosen (suggestions welcome!) Galactic Microquasars Extra-galactic AGN LSI +61 303 Elisa Bernardini

  16. Rate of neutrinos in AMANDA from selected source candidates • ~ one event/year per source bin • Adjustable with bin size AMANDA 2000-2004 Elisa Bernardini

  17. Definition of a coincidence with gamma-ray flares neutrino • gamma-ray flux ? ? • Time window for the coincidence • Topology of the gamma-ray flares • Both are related to the probability of random coincidences between atmospheric (background) neutrinos and gamma-ray flares Elisa Bernardini

  18. Work in progress • Look at existing gamma-ray data • Toy estimate of significance of coincidences VERY PRELIMINARY Expected neutrino background: 1 Prob. to observe a gamma-ray flare: 1% Expected neutrino background: 1 Prob. to observe a gamma-ray flare: 5% s s Coin. Gamma-ray flares Coin. Gamma-ray flares Observed neutrinos Observed neutrinos Elisa Bernardini

  19. How simultaneous observations could enhance the significance • Toy example: • Assume knowledge of the probability to observe a flare • 3 observed neutrinos, 1 background expected (1 year): 1.4 s • Source with 1% prob. to observe a gamma-ray flare Simultaneous neutrino and gamma ray observation: • Would help confirming/discarding first indications of neutrino signals: • Time correlation: enhance the significance • If signal, neutrino fluxes have to be consistent with gamma-ray phenomenology: take simultaneous data Elisa Bernardini

  20. Challenges • Rate of gamma-ray flares unknown • Systematic gamma-ray monitoring of interesting objects • E.g. VERITAS long-term monitoring plan • Operation of dedicated HEGRA-like telescopes [Lorenz, Mannheim, Rhode] • Estimate the rate based on existing data • Compilation of gamma-ray data in progress • Try to estimate confidence intervals • Un-blinding issues with neutrino telescope • Define cuts a priori • Work on appropriate analysis methods • Discovery potential under study • AMANDA will not operate as standalone starting in 2007 • Short test period in 2006 to establish the technique and the communication infrastructure? • Formal proposal discussed within the IceCube Collaboration • Explore and discuss improved ToO methods for IceCube Elisa Bernardini

  21. State of the art in multi-messenger studies with AMANDA/Icecube • Nine years of AMANDA data analyzed • Results compatible with atmospheric neutrinos • IceCube expected to detect neutrinos from AGNs, GRBs and some galactic sources • Perspective for multi-messenger study: • Enhance the chance to discover neutrino sources • Better understand the phenomenology associated to first neutrino signals! • Perspective of a possible Target of Opportunity neutrino trigger • Address few sources • Challenging but … • Promising: can dramatically change the significance Possible future scenarios Elisa Bernardini

  22. Extra Elisa Bernardini

  23. Probability of random coincidences trigger window for gamma-ray observations neutrino events time gamma-ray flares time • Outcome of one year of observation: (nnobs , ngcoinc ; nnbck, pgDt) • Significance of such an observation: nnobs observed neutrinos nnbck background neutrinos ngcoincobserved gamma-ray flares Dt·pgDt expected gamma-ray flares pgDt probability of detecting a gamma-ray flare in the time Dt Elisa Bernardini

  24. A scheme for the trigger

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