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

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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

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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