NEUTRINO POINT-SOURCE ANALYSIS IN ICECUBE Juan Antonio Aguilar - PowerPoint PPT Presentation

NEUTRINO POINT-SOURCE ANALYSIS IN ICECUBE Juan Antonio Aguilar Vulcano Italy, 2010 IC40 All-Sky Stacking Conclusions 1

IC40 CONFIGURATION 2

ICECUBE IceCube Completion with 80 (+ 6) strings by January 2011 IceCube 79 (2010) 79 strings are in operation. IceCube 59 (2009-10) IceCube IC59 data is being processed. Analysis starting now. IceCube 40 (2008-9) IC40 has approx. 2 x effective area of the previous IC22. IC40 data has been analyzed for point sources. IC40 All-Sky Stacking Conclusions 3 Juan Antonio Aguilar Vulcano Workshop 2010

IC40 MUON SAMPLE Detector rates: µ IC40 rate evolution atm. ν SMT filter Strings Year Livetime rate final Upgoing rate Downgoing (Hz) rate (Hz) Trigger 9 2006 137 d 80 6 1.7 L2 (muon filter) 22 2007 276 d 450 20 18/d 40 2008 375.5 d 1100 23 40/d L3 (muon sample) 59 2009 320 d 1900 24 Atm. muons Atm. neutrinos 79 2010 2300 40 IC40 All-Sky Stacking Conclusions 4 Juan Antonio Aguilar Vulcano Workshop 2010

IC40 MUON SAMPLE Detector rates: µ IC40 rate evolution atm. ν SMT filter Strings Year Livetime rate final Upgoing rate Downgoing (Hz) rate (Hz) Trigger 9 2006 137 d 80 6 1.7 L2 (muon filter) 22 2007 276 d 450 20 18/d 40 2008 375.5 d 1100 23 40/d L3 (muon sample) 59 2009 320 d 1900 24 Atm. muons Atm. neutrinos 79 2010 2300 40 Get all sky cutting on total charge IC40 All-Sky Stacking Conclusions 5 Juan Antonio Aguilar Vulcano Workshop 2010

ANGULAR RESOLUTION Cumulative distribution of the Point Spread Function for different IceCube configurations: ‣ IC40 has already in one direction a size equals to IceCube (IC80) 50% angular resolution IC40 Top view IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 6

EFFECTIVE AREA Solid-angle averaged neutrino effective area: The smaller the zenith, the more sensitive to higher energies. 0-30 30-60 South Pole 60-90 IC80+DC6, ϴ = (120 ◦ - 90 ◦ ) IC80+DC6, ϴ = (150 ◦ - 120 ◦ ) 120-90 IC80+DC6, ϴ = (180 ◦ - 150 ◦ ) IC40, ϴ = (120 ◦ - 90 ◦ ) IC40, ϴ = (150 ◦ - 120 ◦ ) IC40, ϴ = (180 ◦ - 150 ◦ ) 150-120 180-150 There is a factor 2 increase at high energy and > 8 at low energies. IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010

ALLSKY ANALYSIS 8

LIKELIHOOD AND DENSITY FUNCTIONS Signal pdf: Likelihood Space around track solution fit to paraboloid: width = σ !" %&'()$ !"#$ IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 9

LIKELIHOOD AND DENSITY FUNCTIONS Signal pdf: IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 10

LIKELIHOOD AND DENSITY FUNCTIONS Background pdf: Signal pdf: Scrambled real data IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 11

LIKELIHOOD AND DENSITY FUNCTIONS Background pdf: Signal pdf: Likelihood: IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 12

LIKELIHOOD AND DENSITY FUNCTIONS Background pdf: Signal pdf: Likelihood: Maximization of the likelihood ratio: The final significance is   L (ˆ , ˆ n s ) γ Estimates that log λ = log determined by   maximize the L ( n s = 0)   scrambling the data in Likelihood r.a. and repeating the analysis. IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 13

IC40 ALLSKY ANALYSIS SAMPLE Northern Sky Southern Sky Two main components in the final analysis sample: - The Southern sky (downgoing atm. muons) has a better angular resolution. - The Northern sky (upgoing atm. neutrinos) has a lower energy range. IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 14

IC22 ALL SKY RESULTS +75° Atm. neutrinos +60° +45° -log 10 p +30° +15° 24h Hottest spot found at r.a. 153.4° , dec. 11.4° Post-trials p-value of analysis is ~ 1.34% (2.2 sigma) Paper published by ApJL, 701:L47, 2009 IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 15

IC22 ALL SKY RESULTS +75° Atm. neutrinos +60° +45° -log 10 p +30° +15° 24h 0h Atm. muons ‐15° ‐30° Analysis extended to ‐50° dec ‐45° First IceCube search for point sources above the horizon optimized for higher energies Paper published by Phys. Rev. Lett. 103, 221102 (2009) IC40 All-Sky Stacking Conclusions Juan Antonio Aguilar Vulcano Workshop 2010 16

IC40 EVENT MAP Atm. neutrinos Atm. muons Jon Dumm ‣ Livetime: 375.5 days ‣ Events: 37290 (14139 up-going, 23151 down-going) IC40 All-Sky Stacking Conclusions 17 Juan Antonio Aguilar Vulcano Workshop 2010

IC40 SIGNIFICANCE MAP Preliminary Atm. neutrinos Atm. muons Jon Dumm ‣ Log-likelihood is calculated on a fine grid: 0.1° x 0.1° ‣ Significance comes from the hottest single spot, calculated as the fraction of scrambled trials with equal or higher significance – robust result IC40 All-Sky Stacking Conclusions 18 Juan Antonio Aguilar Vulcano Workshop 2010

IC40 SIGNIFICANCE MAP Preliminary Atm. neutrinos Atm. muons Ho#est loca+on in the all‐sky search is: Jon Dumm Ra=115.05, Dec=15.05 ‣ Log-likelihood is calculated on a fine grid: 0.1° x 0.1° ‣ Significance comes from the hottest single spot, calculated as the fraction of scrambled trials with equal or higher significance – robust result IC40 All-Sky Stacking Conclusions 19 Juan Antonio Aguilar Vulcano Workshop 2010

IC40 ALLSKY RESULTS ‣ The distribution of results for 10000 scrambled skymaps. ‣ For each scrambled trial, the same analysis is performed. ‣ The hottest spot in each trial yields 96% the -log 10 (p min ) that goes into this histogram. 9588 of the 10000 scrambled skymaps had a -log 10 (p min ) equal or greater than that of the real dataset ➜ all‐sky p‐value = 96% . observed value IC40 All-Sky Stacking Conclusions 20 16 Juan Antonio Aguilar Vulcano Workshop 2010

UPPER LIMITS (90% CL) Preliminary ‣ Median Neyman sensitivities/UL for E -2 neutrino spectrum ‣ Discovery potential at 5 σ (P = 50%) takes ~3x more flux ‣ IceCube (IC86) ~2x better than IC40 IC40 All-Sky Stacking Conclusions 21 Juan Antonio Aguilar Vulcano Workshop 2010

SPECTRAL INDEX How well we can fit the spectral index 1-sigma depends on the E -3 number of signal events. Softer spectrum E -2 require higher number E -1.5 of events to claim a a discovery. Number of events for a 50% discovery potential IC40 All-Sky Stacking Conclusions 22

SPECTRUM CUTOFF ‣ Analysis is optimized for E -2 spectra. ‣ Gamma spectra from galactic sources exhibit cut-offs at energies of about 5-30 TeV. ‣ Southern sky is more sensitive to a cut-off. But we are still d Φ / dE = Φ 0 E − 2 exp( − E / E cutoff ) sensitive in the Northern hemisphere even if we loose sensitivity for cut-offs < 100 TeV IC40 All-Sky Stacking Conclusions 23 Juan Antonio Aguilar Vulcano Workshop 2010

STACKING ANALYSIS 24

STACKING ANALYSIS ‣ Combine the signal from similar sources: Stacking ‣ Small modification in the PS search: Sum of signal pdf ‣ The gain by adding more identical sources is somewhere between: - √ nSources ➜ expectation for high background - nSources ➜ expectation for low background IC40 All-Sky Stacking Conclusions 25 Juan Antonio Aguilar Vulcano Workshop 2010

MILAGRO-FERMI SOURCES: THE GEV – TEV CONNECTION Abdo et al. 2009, arXiv:0904.1018v3 ‣ Milagro showed that many Fermi GeV gamma ray sources extend to TeV ‣ Of 34 galactic Fermi BSL sources in Milagro 6 (14) are observed with > 5 (3) σ ‣ Probability of 4 or more excesses > 3 σ in 34 trials is p = 1.5 x 10 -7 ‣ Strong evidence for multi-TeV emission from Galactic BSL sources as a class. IC40 All-Sky Stacking Conclusions 26 Juan Antonio Aguilar Vulcano Workshop 2010

NEARBY CLUSTER OF GALAXIES Murase et al. 2008, arXiv:0805.0104v2: Name Size (°)RA(°) Dec(°) Virgo 8.0 186.6 12.7 ‣ Cluster of Galaxies (CG) Centaurus 1.2 193.2 ‐41.3 might explain CR between Perseus 2.4 50.0 41.5 Coma 1.8 195.0 28.0 the second knee and the Ophiuchus 0.9 247 ‐24.5 ankle. ‣ Different models CR density predicts neutrino emission. ‣ Detection of individual neutrino signal is still challenging for IceCube-like detectors ➜ Stacking . IC40 All-Sky Stacking Conclusions 27 Juan Antonio Aguilar Vulcano Workshop 2010

Preliminary IC40 STACKING RESULTS Stacked Fit Number 90% Upper P-value from Fit Spectral Sources (# of of Source Limit scrambling Index sources) Events (10 − 12 TeV − 1 cm − 2 s − 1 ) Milagro (17) 41.2% 4.2 -2.8 8.0 Nearby 82.0% 0.6 -3.9 10.6 Clusters (5) Starbursts 28.1% 2.9 -2.3 36.5 Galaxies (127) Dense ISM ➜ Elevated star formation rates ➜ SNR ➜ CR ➜ Neutrinos Becker et al. 2009, arXiv:0901.1775v1 IC40 All-Sky Stacking Conclusions 28 Juan Antonio Aguilar Vulcano Workshop 2010