Latest upper limits on neutrino fluxes from
point-like sources with AMANDA-II
Markus Ackermann
for the IceCube collaboration
[email protected]
DESY
http://icecube.wisc.edu
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Outline
I
The AMANDA-II point source search
II
Results from the analysis of 1001 effective days of data
(2000-2004)
III Comparison of upper limits to a selection of predicted
neutrino fluxes
IV
Summary
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
AMANDA-II
90º S
677 Optical Modules
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Search for point sources
2000-2004
data set
1001 effective
days
On-Source
= 2.25° - 3.75°
Off-Source
Final neutrino sample:
Atm-n simulation:
4282 events
3627 – 4912 events
Search for signal from candidate sources
Scan of full northern sky
Stacked search of generic source classes
Atm-n Background from ‘off-source’ data  only statistical error ~ 7%
Flux upper limits by comparison to signal simulation
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Neutrino effective areas
muon neutrinos
tau neutrinos via
nt  t m + nt+ nm
(17.7 %)
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Sensitivity
E2 dF/dE [10-7 GeV cm-2 s-1]
Sensitivity to neutrino flux dF/dE ~ E-2
Contribution of nt to sensitivity 10-16% (declination dependent)
nm + nt is the strongest limit on the neutrino flux for a nm:nt = 1:1 flavor ratio
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Results I: Candidate sources
Excess
parameter
-log10 P
Flux upper limit (15% sys, 7% stat)
F0 @ 90% CL [10-7 GeV cm-2s-1]
for F = F0 E-2
F0 (nm )
F0 (nm +nt ) (1:1)
6 / 7.37
0.13
0.42
0.74
Markarian 501
8 / 6.39
0.51
0.85
1.47
1ES1959+650
5 / 4.77
0.29
0.78
1.35
M87
6 / 6.08
0.25
0.49
0.87
3C273
8 / 4.72
0.98
1.00
1.80
SS433
4 / 6.14
0.06
0.27
0.48
LSI +61 303
5 / 4.81
0.28
0.74
1.26
Cygnus X-1
8 / 7.01
0.39
0.77
1.32
Cygnus X-3
7 / 6.48
0.50
0.68
1.18
Cassiopeia A
5 / 6.00
0.15
0.51
0.89
Crab Nebula
10 / 6.74
0.84
1.02
1.78
AGN
Markarian 421
Microquasar
Events observed/
background
(2000-2004)
SNR
Source
32 sources in candidate list
No significant excess, no indication for a neutrino source
Systematic error of 15% on signal prediction included in limits
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Results II: Grid search
Significance / s
2000-2004
Largest fluctuation:
3.7s
at 12.6 h, +4.5 deg
Random events
69 out of 100 sky maps
with randomized events
show an excess higher than
3.7s
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Limit map
90% confidence level flux upper limits for the northern hemisphere in
0.5 deg bins (15% systematic error included)
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Source stacking analysis
Search for an excess of events
from several sources combined
AGNs grouped in classes of
potential high energy neutrino
sources
Assumption: neutrino flux is
linearly correlated with luminosity
Flux upper limit in units of
10-7 GeV cm-2s-1
for differential flux dF/dE ~ E-2
Source class
Nsrc
Flux
IR Blazars
11
1.2
keV Blazars (HEAO-A)
3
0.59
keV Blazars (ROSAT)
8
0.63
GeV Blazars
8
0.32
Uni. GeV sources
22
3.2
TeV Blazars
5
0.69
GPS and CSS
8
0.57
FR-I Galaxies
1
0.54
FR-I Galaxies (no M87)
17
0.43
FR-II Galaxies
17
3.5
Radio-weak sources
11
1.3
A. Gross, Ph.D thesis, University of Dortmund
Achtenberg et al., “On the selection of AGN …”, Accepted by Astropart. Phys.
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Comparison to selected models
Specific theoretical models for neutrino emission from a single source rarely
show a pure E-2 spectrum
Variation of the spectral index between g=1 and g=3 shifts the peak energy
of the detected neutrinos by 6 orders of magnitude
dF/dE ~ E-3
dF/dE ~ E-2
dF/dE ~ E-1
Specific limits have to be calculated for the sources/spectra modelled
based on the effective area of AMANDA-II
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
E3 dF/dE [10-3 GeV2 cm-2 s-1]
Sensitivity to different spectra
Sensitivity to dF/dE ~ E-1 :
Declination dependence due
to neutrino absorption
Markus Ackermann
E dF/dE [10-13 cm-2 s-1]
Sensitivity to dF/dE ~ E-3 :
Declination dependence from
detector efficiency
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Crab nebula
Guetta & Amato: Rescaling of gamma ray flux (Nn,exp=0.16)
Bednarek & Protheroe: Heavy nuclei accelerated in outer gap (Nn,exp=0.08)
Bednarek: Time evolution of pulsar wind nebula (Nn,exp=0.03)
Link & Burgio: Ions accelerated near pulsar surface (Nn,exp=1.2)
Flux limits and predictions
shown correspond to nm+nt
flux on earth for a flavor
ratio of nm:nt = 1:1
Crab nebula
Nobserved
10
Nbackground
6.74
Event upper limit
(90% CL)
10.1
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
X-ray binaries
Distefano et al.: pg-interaction in the jet with int. and ext. photons
(Nn,exp=7.8)
Bednarek: pp-interaction in WR star and accretion disk after
photodissoziation of heavy nuclei in the jet (Nn,exp=2.1 / 1.4)
Anchordoqui et al.: Protons accelerated in electrostatic gap interact in
accretion disk (Nn,exp=0.12)
SS433
Nobs / Nbg
4 / 6.14
Event upper limit
3.1
(90% CL)
Cygnus X-3
Nobs / Nbg
7 / 6.48
Event upper limit
6.4
(90% CL)
AO 0535+625
Nobs / Nbg
Event upper limit
(90% CL)
Markus Ackermann
7 / 6.48
6.4
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
M87
Protheroe et al.: M87 is considered a misaligned BLLac object in the Proton
Synchrotron Blazar model (Muecke et al. 2002)
Nn,exp= 0.06 (LBL)
Nn,exp= 6 10-4 (HBL)
M87
Nobserved
Nbackground
Event upper limit
(90% CL)
Markus Ackermann
6
6.08
Protheroe et al. LBL (2004)
Protheroe et al. HBL (2004)
5.3
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
EGRET Blazars
Neronov and Semikoz: Model for “typical GeV loud Blazar”, pg-interaction in
the AGN core
Nn,exp= 0.04 - 1.1 (QSO 0528+134)
Nn,exp= 0.006 – 0.14 (QSO 0954+556)
QSO 0528+0134
Nobs / Nbg
4 / 6.08
Event upper limit
3.2
(90% CL)
variation of
beaming
angle for
n-emission
QSO 0954+556
Nobs / Nbg
Event upper limit
(90% CL)
Markus Ackermann
2 / 6.26
1.4
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Summary and Outlook
5 years of data (1001 effective days) of the AMANDA-II detector
have been analyzed for a signal from neutrino point sources.
No statistically significant source of neutrinos has been found so far.
The analysis provides the most stringent limits on neutrino fluxes
from point sources on the northern hemisphere.
Current models of neutrino emission from Microquasars can be
constrained by the results.
From the end of 2007 IceCube will improve the limits beyond the
reach of AMANDA-II .
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
BACKUP SLIDES
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Neutrino effective area
nm (2000-2004)
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Neutrino event selection
extraterrestrial neutrinos
few events expected
2000-2004
data set
Event selection
Atmospheric neutrinos
 103 events / year
1001 effective
days
Revt
Ratm-n
Triggered events
100%
100%
Directional cuts
0.11 %
87%
Topological cuts
5 10-5 %
35%
Nevt
Final neutrino sample
Atm-n simulation
4282
3627 - 4912
Cosmic rays
Muons from air showers
 109 events / year
Markus Ackermann
„Blind“ event selection to avoid
statistical biases
Selection optimized for hard
and soft spectra
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Systematics
Main contributions the systematic error of the point source
analysis are
average OM sensitivity (~ 10%)
rock density ( up to 7%)
detector simulation inaccuracies (~ 7 %)
Uncertainty of average OM sensitivity can be strongly
constrained from zentith distribution of atmospheric neutrinos
(30%  10 %)
Total systematic uncertainty on the signal efficiency
E-2 spectrum:
+10 / -15 %
E-3 spectrum:
+5 / -20 %
atmos. spectrum: +5 / -25 %
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Systematics summary II
Zenith distribution of events in the point source sample
Predictions from atmospheric neutrino simulation is shown with its
systematic error interval
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
3C273
Nellen et al.: pp interaction in AGN core (Nn,exp= 0.86)
Stecker and Salamon: pg interaction in AGN core (Nn,exp= 0.81)
Mannheim: pp and pg interaction in the Blazar jet (Nn,exp= 0.01)
Diffuse flux predicitons
from Nellen et al. and
Stecker and Salamon
already excluded by
AMANDA-II limits
3C273
Nobserved
8
Nbackground
4.72
Event upper limit
(90% CL)
9.6
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06
Markarian 421
Muecke et al.: Model of Markarian 421 as High frequency peaked BLLac in
the Proton Synchrotron Blazar model (Nn,exp~ 0 )
Markarian 421
Nobserved
6
Nbackground
7.37
Event upper limit
(90% CL)
4.1
Markus Ackermann
The multimessenger approach to high energy gamma ray sources, Barcelona, 04.07.06-07.07.06