Transcript Slide 1
The search for extra-terrestrial
sources of high energy neutrinos
with IceCube
Gary C. Hill
University of Wisconsin, Madison
for the IceCube collaboration
Photograph: Forest Banks
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
It’s a mysterious universe!
Messenger particles for
high energy astronomy:
cosmic rays
charged - bad
gamma rays
neutral - good
absorbed - bad
neutrinos
neutral - good
not absorbed good and bad!
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Neutrino and gamma production
in cosmic ray accelerators?
pp, p
0
-rays
from
synchrotron
The TeV gammas?
e e
e e
Let’s look for
these neutrinos!
Hadronic accelerator? –
cosmic ray origin?
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Cosmic ray induced
“guaranteed sources”
pp, p
0
Cosmic rays on Cosmic
Microwave Background:
GZK neutrinos
EHE: 109-10 GeV
e e
e e
Cosmic rays on
galactic plane:
galactic plane
neutrinos
Cosmic rays on the earth’s atmosphere:
Atmospheric neutrinos
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
The high-energy neutrino sky
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Atmospheric Neutrinos
Cosmic Ray
pions, kaons and charm
e+
+
π+
e
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
e N e X
background
atmospheric
muon
Direction:
Reconstruction of
Cerenkov cone
Energy:
Counting of modules
that see photons
N X
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Event Signatures in IceCube
1013
eV (10 TeV)
~90 hits
6x1015 eV (6 PeV)
~1000 hits
Multi-PeV
AMANDA
+N+...
± (300 m!)
+hadrons
signature
signature
Expect about 100,000 events/yr
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Where are we pointing?
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Moon declination during first 15 years
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
RA distribution relative to moon
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Li and Ma significance distribution
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Point source searches
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
IC40 6 month all-sky point source search
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
IC40 6 month all-sky point source search
pre-trial significance 10-4.4
expected in 61% of random skies
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Search for a diffuse signal with IC40
Range of
spectral slopes:
start with E-2
Diffuse models
all harder (~E-2) than
atmospheric (~E-3.7):
energy separation
Nch variable
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Energy separation:
Nch variable
Blind analysis:
Best limit setting power
(model rejection potential)
Nch>100
E-2 test flux
Atmospheric
neutrinos
Blind region
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Sensitivity:
for bg=6.1 events
median event limit 5.84
Flux limit : 5.84/66.7x10-6
= 8.8 x 10-8
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Unblind the data:
6 events observed
event limit 5.84
Flux limit : 5.84/66.1x10-6
= 8.8 x 10-8
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Reconstructing The Muon energy loss
photo-nuclear
pair-creation
bremsstrahlung
Approximate as:
k
log P({ni } | {i }) ni logi N log
i 1
dusty
Formulate LLH:
e+e-
clean
Incorporate Ice Properties:
shallow
deep
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Energy estimator comparison
Reconstructed dE/dX
Number of Channels
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Atmospheric
neutrinos
E-2 test flux
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Likelihood shape analysis - probability
of observable shape distribution {ni }
given theory {μi} ?
Product of Poisson probabilities over bins:
i ( ) ( )
P ({ni } | {i ( )})
e
ni !
i 1
{1, 2 ,..., m , m1 ,..., k }
k
ni
i
m parameters of interest; k-m nuisance parameters
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Atmospheric neutrinos only
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Number of prompt
Allowed E-2 and prompt contributions
Number of E-2
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Atmospheric and E-2 neutrinos
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Number of prompt
Allowed E-2 and prompt contributions
Number of E-2
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Atmospheric, E-2 and prompt neutrinos
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
Number of prompt
Allowed E-2 and prompt contributions
Number of E-2
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009
IC40 diffuse sensitivity
Gary C. Hill, CCAPP Symposium 2009 , Ohio State University, October 12th, 2009