Search for Astrophysical Neutrino Point Sources at Super-Kamiokande

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1 Search for Astrophysical Neutrino Point Sources at Super-Kamiokande Yusuke Koshio for Super-K collaboration Kamioka, ICRR, Univ. of Tokyo LNGS, INFN Super-Kamiokande detector Recent results of search for neutrinos from Astrophysical point sources GRB B WIMP annihilation in the Sun and Galactic center

2 Super-Kamiokande (SK) 1885 Outer PMTs for cosmic muon veto 50kt water Cherenkov detector 22.5kt fiducial volume 41.4m Inner PMTs Cherenkov light 20 PMT photocathode coverage Kamioka (inner) SK-1 11,146 40% SK-2 5,182 19% SK-3,4 11,129 40% neutrino charged particle 39.3m SK 1000m Placed inside the Kamioka mine 1000m underground (2700m water equivalent)

3 Multi purpose detector SN G.C. Solar ν Relic SN ν T2K ν Atmospheric ν Wide energy range (MeV~TeV) of the neutrino detector Dark matter search Proton decay search etc SK Astrophysical ν? MeV GeV TeV

4 History of SK (and its related) Start data taking 1998 Evidence of atmospheric ν oscillation (SK) K2K started 2001 Evidence of solar ν oscillation (SK+SNO) data taking was stopped for detector upgrade Accident partial reconstruction Vulcano workshop, 28 th of May, data taking was resumed 2005 Confirm ν oscillation by accelerator ν (K2K) data taking was stopped for full reconstruction data taking was resumed electronics upgrade T2K : Start beam commissioning Start physics run

5 Motivation of search for the astrophysical neutrinos in SK Though the effective area is not so large (~1200 m 2 ), not reach the highest energy comparing to the other experiments, Sensitive to the broad sky (decline +54~- 90 deg) including galactic center, sensitive area Precise measurement µ for lower energy region, ν E>~1.6GeV is available. SK

6 Related papers in SK astro-ph/ , ApJ, 578, 317 (2002) hep-ph/ Desai et.al., PRD, 70, (2004) astro-ph/ Swanson et.al., ApJ, 652, 206 (2006) astro-ph/ , ApJ, 652, 198 (2006) Desai et.al., Astropart. Phys., 29, 42 (2008) Thrane et.al., ApJ, 697, 730 (2009) Thrane et.al., ApJ, 704, 503 (2009) Proceedings of ICRC09 Tanaka et.al. (to be published soon) Also see

7 Event categories in SK For solar neutrinos (<100MeV) ( lowe ) For atmospheric neutrinos (>100MeV) Fully contained ( FC ) Single/Multi ring electron/muon like Partially contained ( PC ) Upward going muons ( upmu ) Stopping Through Non-showering/Showering single ring stopping PC multi ring through

8 upmu event in SK Three categories (MC) exit SK Stopping enter ν interaction with rock Through Non-showering Showering

9 Astrophysical point sources Four searches All the sky without any assumptions about a priori suspected sources, tabla rasa. 16 suspected candidates, as 4 magnetars, 4 plerions, 3 supernova remnants, and 5 microquasars, with estimated distances 0.3~50kpc 27 ultra-high-energy cosmic rays observed by Auger, which may be linked to AGN. Among ~2200 GRBs in the catalogs, 971 GRBs met the criteria of occurring during SK live time with a zenith angle no greater than 8 deg above the horizon.

10 Analysis in SK SK-I,II and part of SK-III, 2623days (Apr.1,1996 ~ Aug.11, 2007) All the upward though going muon (3134) were used. 2 Assume the energy spectrum as dφ ν / de E Energy threshold is 1.6 GeV Maximum likelihood ratio method; =2*log[L(α fit )/L(BG)] was used as a signal strength. L: likelihood function α: probability of being point source signal (fitting parameter) For GRB, search event with 1000sec timing window.

11 tabla rasa search Observed upmu event in SK. Showering * Non-showering Neutrino flux limit Significance this work MACRO (2001) AMANDA (2009) No statistically significant signals were observed

12 Correlation with several sources 16 suspected objects One (SNR RX J ) has large signal strength value. The probability of the chance occurrence is 2.5%. Upper limit of neutrino flux in each sources are in the next page UHE gamma rays No statistically significant signal was found. Upper limit of neutrino flux (averaging over 27 targets) is Φ 90% ν = (1.06 ± 0.12) 10 GRBs Among 971 GRBs, one (GRB D) was time and spatial coincident with upmu event. The probability of the chance occurrence is 4.7%. 90% Upper limit of neutrino flux is Φ = ± 0.007cm 7 cm ν 2 s 1 2

13 Suspected candidates Source type Flux limit (cm -2 sec -1 ) SGR SGR E SGR Crab Vela X G MSH15-52 RX J Vela Jr. MGRO J SS433 Magnetar Magnetar Magnetar Magnetar plerion plerion plerion plerion SNR SNR SNR microquasar GX339-4 Cygnus X-3 GRO J XTE J microquasar microquasar microquasar microquasar

14 GRB B Search for coincident events with 1000 sec timing window for all the categories in SK. Results Event category BG expected observed event lowe FC PC upmu UHE (up going) x10-6 No statistically significant coincidences were observed Upper limit of neutrino flux (cm -2 ) lowe 5.1x x10 7 FC/PC 3.5x x10 4 upmu UHE (up going) 1.2x x x x x x10 4

15 WIMP search (this time analysis) Neutrinos generated by the WIMP annihilation; Induced signal from the Sun (Spin Dependent) χ χχ bb ( soft ), WW ( hard ), ZZ, HH, etc. Sun χ SK ν µ A.Gould, ApJ, 388, 338 (1992) Earth Induced signal from the Galactic Center charged particles Figure from J.Edsjo neutrinos

16 Search for the signal from the Sun Entire SK-I~III upmu sample ( days) Red: atmospheric MC with neutrino oscillation, Black: Data No significance excess was found. Sun Sun Su

17 Flux limit of WIMP induced upmu from the Sun WIMP annihilation mode χχ bb (soft mode) χχ WW (hard mode) This work This work Best limit was obtained several WIMP mass region

18 Limit of the SD cross section Direct detection telescopes This work Relationship between σ SD and flux limit is presented in G.Wikstrom et.al., ( ) We got a good limit for the low mass WIMP

19 Search for the signal from the Galactic center Same as the plot signal from the sun. No significance excess was found. Upmu flux limit (x10-15 cm -2 sec -1 ) 4.11 (θ GC =10 deg.), 9.99 (θ GC =20 deg.), (θ GC =30 deg.) GC GC GC

20 Summary Search for the neutrino signal from astrophysical objects and WIMPs induced events from the Sun and Galactic center using Super-Kamiokande upward going muon events No significant signals were found. Neutrino flux limits in these objects were obtained.

21 upmu (Stopping) Vulcano workshop, 28 th of May, 201

22 upmu (Through / Non-showering)

23 upmu (Through / Showering)

24 istributions of Sun degree =direction of the Sun o significant excess as observed here. Non showering Stopping Red: Atmospheric MC (with oscillation) Cross: data Vulcano workshop, 28 th of May, Showering Sun (Degree)