Neutrino Astronomy at the South Pole Neutrino Astronomy at the South - PowerPoint PPT Presentation

1 Neutrino Astronomy at the South Pole Neutrino Astronomy at the South Pole AMANDA and IceCube AMANDA and IceCube Ignacio Taboada Ignacio Taboada University of California - Berkeley University of California - Berkeley Topics in Astroparticle and Underground Physics Topics in Astroparticle and Underground Physics Zaragoza. Sept 10-14, 2005 Zaragoza. Sept 10-14, 2005 I. Taboada TAUP-2005. Zaragoza

2 The IceCube Collaboration The IceCube Collaboration Sweden: USA: Uppsala Universitet Bartol Research Institute Stockholm Universitet Germany: University of Alabama Pennsylvania State University Humboldt Universität University of California – Berkeley Universität Mainz UK: University of California – Irvine DESY-Zeuthen Imperial College Clark-Atlanta University Universität Dortmund Oxford University University of Maryland Universität Wuppertal Institute for Advanced Study Universität Berlin Netherlands: Japan: University of Wisconsin-Madison Belgium: Utrecht University Chiba University University of Wisconsin-River Falls Université Libre de Bruxelles Lawrence Berkeley National Lab Vrije Universiteit Brussel University of Kansas Universiteit Gent Southern University and A&M Université de Mons-Hainaut College New Zealand: University of Canterbury Antarctica: Amundsen Scott South Pole Station In March 2005, AMANDA merged into the IceCube collaboration I. Taboada TAUP-2005. Zaragoza

3 Neutrino Astronomy Neutrino Astronomy Candidate sources: SN remnants, Quasars – Explained by SN Active Galactic Nuclei – Gamma Ray Bursts – Exotics – Unexplained Astronomical Messengers: Guaranteed sources: Neutrinos: Not absorbed, not Neutrinos – • Atmospheric neutrinos (from π & K decay) deflected. Small cross section → Big Detectors Needed • Galactic plane: CR interacting with ISM, concentrated on Protons. Deflected by Protons – Magnetic fields. Absorbed GZK the disk Photons. Not deflected. Absorbed Photons • GZK – E> 10 TeV (IR) and E>10 PeV (3K) γ   ∆ +  n π + (p π 0 ) p γ I. Taboada TAUP-2005. Zaragoza

4 Neutrino Detection in Antarctic Ice Neutrino Detection in Antarctic Ice O(km) muons ~15 m Θ μν ≈ 0.7 ° ⋅ E ν / TeV  − 0.7 Event reconstruction by Cherenkov light timing O(10 m) cascades Average Ice Properties λ abs ~ 110 m @ 400 nm λ sca ~ 20 m @ 400 nm Most transparent natural solid known I. Taboada TAUP-2005. Zaragoza

5 Amundsen-Scott South Pole Station Amundsen-Scott South Pole Station IceCube IceCube y y South Pole a South Pole a w w y y k k S S Dome Dome Road to work Road to work AMANDA AMANDA Summer camp Summer camp 1500 m 1500 m 2000 m 2000 m [not to scale] [not to scale] I. Taboada TAUP-2005. Zaragoza

6 AMANDA AMANDA 1996 1997 2000 AMANDA-B4 AMANDA-B10 AMANDA-II (first 4-string prototype) (inner core of AMANDA-II) 4 strings 10 strings 19 strings 80 OMs 302 OMs 677 OMs Data years: 1996 Data years: 1997-99 Data years: 2000 – What’s up? “Up-going” “Down-going” (from Northern sky) (from Southern sky) O ptical M odule PMT noise: ~1 kHz We use the Earth as a filter for W down-going atmospheric muons e I. Taboada TAUP-2005. Zaragoza

7 AMANDA Physics Topics AMANDA Physics Topics Results shown in this talk: ✔ Atmospheric neutrinos ✔ Searches for extra-terrestrial fluxes ✔ Neutrino Diffuse fluxes ✔ Neutrino Point sources ✔ Neutrinos from the galactic plane ✔ Neutrinos from GRBs ✔ SNe in the Milky Way Other results: ✔ Searches for WIMPs: Sun/Earth center ✔ Atmospheric muon spectrum ✔ Cosmic Ray composition ✔ Search for magnetic monopoles Agreed collaboration strategy: ✔ Many others ... Blind Analyses I. Taboada TAUP-2005. Zaragoza

8 Atmospheric Neutrinos Atmospheric Neutrinos Atmospheric neutrinos: - Guaranteed test beam - Background for other searches ✔ Neural Network energy reconstruction of up-going µ 's ✔ Regularized unfolding → ν energy spectrum Set limit on cosmic neutrino flux: How much E -2 cosmic ν - signal allowed within uncertainty of highest energy bins? Limit on diffuse E -2 ν μ flux (100 -300 TeV): E 2 Φ ν μ ( E ) < 2.6·10 –7 GeV cm -2 s -1 sr -1 I. Taboada TAUP-2005. Zaragoza

9 Diffuse fluxes Diffuse fluxes ν µ Search All flavor search All flavor search UHE: E E ν > P eV HE: HE: TeV < E TeV < E ν ν < PeV < PeV HE: TeV < E : TeV < E ν < PeV UHE: ν > P eV HE ν < PeV • π 4 π • 4 search search Use directionality + Use directionality + • Earth opaque Earth opaque energy-related variables energy-related variables • Background: brem. from Background: brem. from • Search in the upper Search in the upper µ to reject atm µ to reject atm down-going muons down-going muons hemisphere and close to hemisphere and close to background background • Limits from 1997, 1999 Limits from 1997, 1999 the horizon the horizon • Search confined to up- Search confined to up- and 2000 and 2000 • Bright events: many hit Bright events: many hit going tracks going tracks OMs with several hits/OM OMs with several hits/OM • Use high-quality tracks Use high-quality tracks • Energy-related Energy-related • Limits from 1997 and Limits from 1997 and Signal variables best handle variables best handle 2000-2003 2000-2003 of analysis of analysis Background • Limit from 1997. Limit from 1997. Sensitivity from 2000. Sensitivity from 2000. ν µ ν e ν µ ν τ Limits on ν Limits that assume ν : ν : ν :: 1:1:1 Limits on Limits that assume e : µ : τ :: 1:1:1 µ I. Taboada TAUP-2005. Zaragoza

10 Diffuse fluxes: Summary Diffuse fluxes: Summary I. Taboada TAUP-2005. Zaragoza

11 Neutrino Point Sources Neutrino Point Sources • Search for excesses of events compared to Average upper limit = sensitivity (δ>0°) the background from: (integrated above 10 GeV, E -2 signal) • The Northern sky • A set of selected candidate sources average flux upper limit [cm -2 s -1 ] • Cuts optimized by declination bands • Require good pointing resolution AMANDA-B10 (good quality events) • Background estimated from exp. data with randomized α (i.e. time) AMANDA-II • Sensitivity ~ flat up to horizon • Significant improvement w.r.t. first analysis with AMANDA-B10 sin (δ) Declination averaged sensitivity Declination averaged sensitivity for a E ν spectrum and E ν > 10 GeV for a E -2 spectrum and E ν > 10 GeV -2 ν At the south pole: Φ ν lim ~ 0.6·10 -8 cm -2 s -1 δ= 0 o → (horizontal) δ declination δ= 90 o ↑ (vertical) I. Taboada TAUP-2005. Zaragoza

12 Neutrino Point Sources Neutrino Point Sources Event selection optimized for both E -2 & E -3 spectra Data from 2000-2003 (807 days) 3369 ν from northern hemisphere 3438 ν expected from atmosphere Maximum significance: 3.4 σ Probability of a background fluctuation: 92 % I. Taboada TAUP-2005. Zaragoza

13 Neutrino Point Sources Neutrino Point Sources Selected objects and full scan of the northern sky: On-Source No statistically significant effect observed Off-Source Sensitivity Source # of ν Expected Flux Upper Limit Φ ν /Φ γ ~2 Φ 90% (E ν >10 GeV) bckg events (4 years) (4 years) [10 -8 cm -2 s -1 ] 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 Preliminary Crab Nebula 10 5.36 1.25 (or higher) given … out of 33 Sources the number of trials is 64% Systematic uncertainties under investigation We have also performed a time-dependent search for specific sources. No evidence of sources found. I. Taboada TAUP-2005. Zaragoza

14 Neutrinos from the Galactic Plane Neutrinos from the Galactic Plane • Location of AMANDA not optimal  reach only outer region of the galactic plane: 33 o < δ < 213 o • Three signal ansatz: Line source, Gaussian source, Diffuse source • Limits include systematic uncertainty of 30% on atm. ν flux • Energy range: 0.2 to 40 TeV - Gaus. limit - Model On-source On-source Expected Limit region events bckg. - 6.4x10 -5 (line) - GeV -1 cm -2 s -1 rad -1 2 o 128 129.4 6.6x10 -4 (diffuse) - GeV -1 cm -2 s -1 sr -1 4.8x10 -4 (gauss) - 4.4 o 271 283.3 GeV -1 cm -2 s -1 sr -1 - I. Taboada TAUP-2005. Zaragoza