neutrino point source searches with amanda-ii m -daq
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Neutrino Point Source Searches with AMANDA-II -DAQ
Jim BraunIceCube Fall 2007 Collaboration Meeting
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 2
Progress Since Lake Geneva
• 2005 unblinded:– http://www.icecube.wisc.edu/~jbraun/2005_point_source/
• 2006 unblinded:– http://www.icecube.wisc.edu/~jbraun/2006_point_source/
• Improvements in methodology:– http://www.icecube.wisc.edu/~jbraun/2006_point_source/sensitivity.html
• Internal report on methodology coming soon
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 3
Review: Sensitivity
Improvement:~30%
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 4
Use of Energy Information
• Mean number of signal events required to reach 5 in 50% of simulated experiments at =42.5o
• 2006 data is background
• Compare unbinned search with and without using Nch
• Utilizing Nch information improves discovery potential for spectral indices < 3.3
• Effect is 30% for E-2, representing a 45% total improvement over the binned search
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 5
2005 Unblinding
log10(p-value)Highest Significance: 3.58
Chance Probability: 69%
Object P-value
MGRO J2019+37 0.152
Mrk 501 0.184
Mrk 421 ~1
NGC 1275 0.064Crab Nebula ~1
Cyg X-3 0.458
GRS 1915+105 0.581
80% Chance of observingp = 0.064 given 26 sources
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 6
2006 Unblinding
SignificanceHighest Significance: 3.58
Chance Probability: 84%
Object P-value
MGRO J2019+37 0.064
Mrk 501 ~1
Mrk 421 0.227
NGC 1275 ~1
Crab Nebula 0.456
Cyg X-3 0.012
GRS 1915+105 0.005
12% Chance of observingp = 0.005 given 26 sources
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 7
2005 + 2006
Significance
3.82
Sensitivity of 2005-2006 analysis nearE2d/dE = 7x10-11 TeV cm-2 s-1
5 year search: 5x10-11 TeV cm-2 s-1
Object P-value 90*
MGRO J2019+37 0.065 12.83
Mrk 501 0.228 8.83
Mrk 421 ~1 5.71
NGC 1275 0.106 10.98
Crab Nebula 0.438 6.67
Cyg X-3 0.033 13.37
GRS 1915+105 0.031 14.12
* 10-11 TeV cm-2 s-1
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 8
Plans for 2000-2006• Expect to combine 2005+2006 with 2000-2004 Zeuthen
five year data set– Will not reoptimize cuts for 2000-2004
• Expected sensitivity: ~3x10-11 TeV cm-2 s-1
• Finish by the end of the year
• Will not include 1997-1999 B10 data as previously planned– 465 total events in most recent 1997-1999 analysis– Considering poorer angular resolution and 25% contamination,
equivalent to less than 40 days AMANDA-II livetime
IceCube Collaboration Meeting Fall 2007 Neutrino Point Source Searches with AMANDA-II -DAQ: 9
The Crab(Because Everyone Keeps Asking)
• 2000-2004: Excess (10 events, 6 expected)• 2005-2006: Slight excess• 2006 IC-9: Excess
• If the excesses are indeed a signal, we would possibly observe ~3for this source– Significance reduced to ~2 with a catalogue of 26
sources– Depends on Nch values of events observed in 2000-
2004
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