Multi-messenger studies of point sources Multi-messenger studies of point sources using AMANDA/IceCube data and strategies using AMANDA/IceCube data and strategies Cherenkov 2005 27-29 April 2005 Palaiseau, France Contents: • The AMANDA/IceCube detection principles • Search for High Energy neutrino point sources: • 4 years time-averaged signals • Transient (time-variable) signals • Observations of the Blazar 1ES1959+ 650 • Towards an extension of multi-wavelength campaigns to neutrino observatories? Elisa Bernardini bernardi@ifh.de http://icecube.wisc.edu
The AMANDA Detection principles Neutrino candidates Muons detected are selected up-going from Cherenkov muon tracks, with good light in ice angular resolution ~ 10 9 events/ Up Down year ~ 10 3 events/ A few year events/ year 2/ 12
Search for a neutrino signal from point sources: 4 years time-averaged ‘Blind-Analysis’: • Event selection and analysis procedures are optimized on events with randomized right ascension and/or time • Background estimated from the data (off-source) On-Source Off-Source Elisa Bernardini - Cherenkov 2005 - Palaiseu, Paris 3/ 12
Search for clusters of events in the Northern sky The data sample: 3329 ↑ observed 3369 neutrino candidates 3438 ↑ expected atm. MC Event selection optimized for both dN/ dE ~ E -2 and E -3 spectra = 2.25 ° -3.75 ° = 807 days Declination averaged Point Sources search: sensitivity , integrated in Search for excesses of events compared to energy (E> 10 GeV), the background from: dN/ dE ~ E -2 : • A set of selected candidate sources lim ≈ 0.6·10 -8 cm -2 s -1 • The full Northern Sky Φ ν 4/ 12
Search for clusters of events in the Northern sky Selected objects and full scan of the northern sky: Preliminary No statistically significant effect observed Nr. of ν Sensitivity Source Expected Flux Upper Limit Φ ν /Φ γ ~ 2 Φ 90% (E ν > 10 GeV) backgr. events [10 -8 cm -2 s -1 ] (4 years) (4 years) for 200 days of “high-state” and Markarian 421 6 5.58 0.68 spectral results 1ES1959+ 650 5 3.71 0.38 from HEGRA SS433 2 4.50 0.21 Cygnus X-3 6 5.04 0.77 Crab Nebula : The Cygnus X-1 4 5.21 0.40 chance probability of such an excess Crab Nebula 10 5.36 1.25 (or higher) given … out of 33 Sources the number of trials is 64% Systematic uncertainties under investigation 5/ 12
Search for a neutrino signal from point sources: transient phenomena ‘Enhance the detection chance by using the time information’: • Search for transient signals, still compatible with the 4 years-averaged flux upper limits IMAGE CREDIT: NASA/Honeywell Max Q Digital Group, Dana Berry Elisa Bernardini - Cherenkov 2005 - Palaiseu, Paris 6/ 12
1. Look at known periods (active states) Search for events in coincidence with known periods of enhanced electromagnetic emission: • Periods and sources selected on the basis of the available multi- wavelength information • Wavelengths investigated are possible indicators for a correlated neutrino emission (X-ray for Blazars and radio for Microquasars) Nr. of ν Source EM light Livetime in Expected curve source periods of backgr. in events in high activity high state high state Markarian 421 ASM/RXTE 141 days 0 1.63 1ES1959+ 650 ASM/RXTE 283 days 2 1.59 Cygnus X-3 Ryle Telesc. 114 days 2 1.37 Multi-wavelength information and theoretical knowledge of the time- correlation with the possible neutrino emission are meager: Search for neutrino flares without a-priori hypothesis on their time of occurrence 7/ 12
2. Search for neutrino flares Preliminary sliding window Search for excesses in time-sliding windows: No statistical significant effect observed events = 2.25 ° -3.75 ° time = 40/20 days for Extragalactic/Galactic Objects Nr. of ν Source Expected Period Nr. of Probability for backgr. duration doublets highest events (4 years) (4 years) multiplicity Markarian 421 6 5.58 40 days 0 Close to 1 1ES1959+ 650 5 3.71 40 days 1 0.34 3EG J1227+ 4302 6 4.37 40 days 1 0.43 QSO 0235+ 164 6 5.04 40 days 1 0.52 Cygnus X-3 6 5.04 20 days 0 Close to 1 GRS 1915+ 105 6 4.76 20 days 1 0.32 GRO J0422+ 32 5 5.12 20 days 0 Close to 1 … out of 12 Sources 8/ 12
Preliminary Triangles: Yellow bars: event times width of sliding search window “A posteriori”: 3 (of 5) events in 66 days Error bars: Period of major outburst off-source measured at different background wavelengths in 2002 per 40 days (and an “orphan flare”) 9/ 12
Red lines: AMANDA – 2.25 o search bin “Orphan flare” (MJD 52429) Probability of a random coincidence with the “orphan flare” or the enhanced γ -ray activity undefined: a-posteriori hypothesis relative to the test 10/ 12
Multi-messenger campaigns? • Overlap of interests between the high energy electromagnetic measurements and neutrino observations: – BL-Lac hadronic/ mixed versus leptonic models : neutrino detection would discriminate scenarios � combined efforts may increase discovery potential – X-ray/ γ -ray time correlation: what is the “frequency” of orphan flares (bias from X-ray triggered γ -ray observations?) – Does the “orphan-phenomenology” represent a “ class ” of cosmic accelerators or is it rather unique ? • Data taking coordination: – Long-term monitoring of the electromagnetic emission of this source and similar (light curves and spectral information) – Target of opportunity triggered by AMANDA/IceCube on-line event filtering? • Data analysis coordination: – Identify common interests and guidelines for possible information exchange policy 11/ 12
Summary • No statistically significant effect observed in the search for point sources of neutrino with 4 years of AMANDA data • Observations of the Blazar 1ES1959+ 650 in coincidence with the “orphan flare”: no conclusive answers possible whether the observed events can be ascribed to the source or are accidental � future observations could shed light on the nature of the source emission (electromagnetic/hadronic) • The results from the point source analysis motivate new search strategies in AMANDA and IceCube • A collaboration between the multi-wavelength community and neutrino observatories could be of mutual benefit • A few “viable” scenarios have been mentioned: – Data taking coordination – Data analysis coordination 12/ 12
Neutrino Astrophysics : The new “Era” -- IceCube Elisa Bernardini - Cherenkov 2005 - Palaiseu, Paris 13/ 12
The IceCube Project A km 3 -size detector at the South Pole: Goals: • Sensitivity to look for neutrinos from AGNs, GRBs … • Study the “knee” region of the cosmic ray spectrum • … AMANDA as Pilot project Extensive technological development (e.g. digital readout) Optimized for energies > TeV Design: 4800 Optical Modules 80 strings (@ 125 meters) Depth: ~ 1400-2400 m Extensive Air Shower Array @ surface: I ceTop Instrumented volume: 1 km 3 Installation: 2005 -2010, started! 14/ 12
Analogy Quasar / Microquasar: SS433: Observational hints of hadronic acceleration from α -spectral lines Promising neutrino source candidate extra-galactic galactic 15/ 12
Search for ν flares: Method Search for excesses of events in sliding time windows of fixed size ( ∆ t): Method: Compare observed and background events in ∆ t. In what follows is shown how to: Select the data sample: use the 4 years data sample (807 days) 1. 2. Select the search window size (time duration): 40 d/ 20 d (* * ) � Depend on signal strength, spectrum and duration (unknown!) Constraints from steady point sources search results: • Upper limit: Flares of duration ∆ t > 100 days are almost excluxed • Lower limit: Sensitivity ratio flares 10-day / 4-years: ~ 3 • Photon flux ratio flare/no-flare state: O(10) from multi-wavelength observations 2. Choose the window size: 1. Choose the data sample: Standard sample (3329 ↑ events): • Detection probability not “too-low” • Limited dependence on flare duration livetime ~ 800 days (0.04 = 32 d) Flare sample (~ 8000 events): Consideration from multi-wavelength different signal energy spectra observations: are shown. • T flare (galactic) < T flare (extragalactic) (* * ) 40 d: Extragalactic / 20 d Galactic sources 16/ 12
Neutrino-Production and Propagation Most models: • Neutrinos produced in hadron-hadron (pp) and hadron-photon (p γ ) interactions followed by meson decay, with different energy yields. + → π + .... 1. A p p Production → µ + ν Neutrinos from µ neutron decay → + ν + ν emerge with much e µ e lower multiplicity + + γ → + π → + π 0 2. A p n p and energy. → µ + ν → γ + γ Spectrum • Hadron spectrum at the source is expected to show a power-law shape (Fermi acceleration) � power law spectrum for neutrinos Propagation Flavor ratio (case 1 and 2): ν e : ν µ : ν τ ~ 1:2:< 10 -5 @ the source ν e : ν µ : ν τ ~ 1:1:1 @ the detector 17/ 12
The AMANDA medium Optical properties: Scattering Data from calibration light sources deployed along the strings and from cosmic rays. Absorption Effective scattering coefficient Absorption length bubbles ice dust dust A stable OMs sub-set On average: operates as Absorption Eff. Scattering “SuperNova length length Noise Rate from Watch” Optical Modules @ 400 nm @ 400 nm AMANDA contributes to < 1.5 kHz 110 m 20 m SNEWS 18/ 12
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