time variable analysis
DESCRIPTION
Time variable analysis. AWG videoconf – November 4 th 2010. A bit of history : 4 presentations during last collaboration meetings : - CERN ( fev 2010): description of the method - Clermont ( may 2010): + results with BBFit - PowerPoint PPT PresentationTRANSCRIPT
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Time variable analysis
AWG videoconf – November 4th 2010
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A bit of history: 4 presentations during last collaboration meetings: - CERN (fev 2010): description of the method - Clermont (may 2010): + results with BBFit - Paris (sept 2010)+MANTS: + results with AAFit
Contents: - Introduction * Motivation * Likelihood method - Analysis with BBFit and AAFit * Data/MC comparison * Performances of the algorithm ( fixed source) * Candidate sources search * Systematic errors - Summary and perspectives
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Introduction: motivation
More than 50% of sources are found to be variable… → Use this time information direclty in the analysis:
* reduce effectively the background* improve the discovery potential over a time
integrated search.
→ Search for signal from blazars AGN – candidate sources for UHECR(p-γ or p-p strong correlation between γ-ray and neutrino fluxes)
γ-ray catalogues:- Fermi (>100 Mev - ~10 GeV)- IACT (>100 GeV)
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Introduction: Likelihood method
Method: unbinned search using a likelihood ratio (Garo’s method)
,
,1,,log
ibkg
ibkgs
iisigs
P
PNntP
Nn
eventN
1i
itimeidiriisig tPPtP ,,, 1,, Liibkg TP Noise
:Signal:
bkgi
bkgsigi
HxPHxP|
|log
eventN
1i
Optimization in order to find the mimimum neutrino flux to have a 3 (5)sigma discovery
Only up-going multiline events (2008 data ~57 days)
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Unbinned analysis: 1) data
Time distribution of the upgoing multi-line events reconstructed with BBFit and select with tchi2<1.8
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Unbinned analysis: 1) data
Time distribution of the upgoing multi-line events reconstructed with BBFit and select with tchi2<41st approx: flat distribution.Next: use direclty this kind of distribution with very loose cut as the time PDF for background
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Unbinned analysis: 2) data/MC comparison
AAFit BBFitReconstruction: AAFit v0r6 (+Antdst)
Reconstruction: BBFit v3r6
MC productions:Add 2ns hit smearing + 0.5ns interline (cf Nickef’s PS) + noise extracted from summary file from all 2008 L12 data.
-Neutrino+antineutrino: Bartol flux- Muons: mupage (~13.9days)
Data: interline offset (cf Nickef’s PS)
MC productions:Add 2ns hit smearing 12L 3pe + 10pe periods
-Neutrino+antineutrino: Bartol flux- Muons: corsika + bugaev normalisation + scale *2
Legend: data: black dots MC un+anu: blue line MC muons: red line MC all: green line
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Unbinned analysis: 2) data/MC comparison
AAFit BBFit
Upgoing events with error estimate β<1º
Upgoing events with nline>1 && nhit>5
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Unbinned analysis: 2) data/MC comparison
AAFit BBFit
All events with β<1º && Λ>-5.4
All events with nline>1 && nhit>5 && tchi2<1.5
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Unbinned analysis: 2) data/MC comparison
AAFit BBFit
Upgoing events with error estimate β<1º && Λ>-5.4
Upgoing events with nline>1 && nhit>5 && tchi2<1.5
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Unbinned analysis: 2) data: number of events
AAFit BBFit
Upgoing events with error estimate β<1º
Upgoing events with nline>1 && nhit>5
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Unbinned analysis: 3) performances
AAFit BBFit
Upgoing events with β<1º && Λ>-4.8, -4.9, -5.0,…-5.8
Upgoing events with nline>1 && nhit>5 && tchi2<1.2, 1.4, 1.6…, 3.0
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Unbinned analysis: 3) performances
AAFit BBFit
Upgoing events with β<1º && Λ>-4.8, -4.9, -5.0,…-5.8
Upgoing events with nline>1 && nhit>5 && tchi2<1.2, 1.4, 1.6…, 3.0 && tcosth>0.17
(Integration E-2 spectrum from 10GeV-10PeV)
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Unbinned analysis: 3) performances
AAFit BBFit
Upgoing events with β<1º && Λ>-5.0, -5.4, -5.8
Upgoing events with nline>1 && nhit>5 && tchi2<1.5, 1.8, 2.0
Unbinned analysis: comparison AAFit / BBFit
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Unbinned analysis: 3) performances
AAFit BBFit
Upgoing events with β<1º && Λ>-4.8, -4.9, -5.0,…-5.8
Upgoing events with nline>1 && nhit>5 && tchi2<1.2, 1.4, 1.6…, 3.0
δ=-40º
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Unbinned analysis with AAFit and BBFit:
Two main steps: 1) Determination of the performances of the unbinned method algorithm:Generation of the events in one single source with one single flare [square shape] with a variable width from 0.1day to 84days and without using the timing information.
2) Candidate sources search: Use the full time PDF of the source extracted from the gamma ray light curve.
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Unbinned analysis with AAFit: fixed search
Yellow: bkgRed: bkg+1 eventGreen: bkg+3 eventsBlue: bkg+5 eventsPink: bkg+7 eventsLight blue: bkg+9 events
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Zero problem: Difficult computation of the sensitivity especially for very short flarecomes from the fact that the probability to have exactly 0 events around one source at less than few degres increases (less problematic for BBFit) Stability of the fit in order to find the cut for 5s Solutions:
Extend the radius of the simulation of the background: 3º->20º Add a small random number to the likelihood ratio: Uniform(10-5) Increase the statistic for the PE generation 105 -> 107 (especially for very restrictive lambda value)
Unbinned analysis with AAFit: fixed search
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Unbinned analysis with AAFit: fixed search
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Stability of the fit 35σ
0.1 day
No timing
No timing
1 day3 days
84 days
Unbinned analysis with AAFit: fixed search
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Number of events needed for a 3σ discovery
Conversion Nevent Flux with the visibility, effective area and live time
Unbinned analysis with AAFit: fixed search
For different cut on Λ value: >-4.8, -4.9, -5.0…-5.8
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No timingUnbinned analysis with AAFit: fixed search
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No timing
25 days
10 days 1 day
5σ3σ
Unbinned analysis with AAFit: fixed search
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Declination : -40º
Unbinned analysis with AAFit: fixed search
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Declination : -40º
Unbinned analysis with AAFit: fixed search
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Unbinned analysis with AAFit: candidate source
Name OFGL Class z F300 σ2NXS
PKS0208-512 J0210.8-5100 FSRQ 1.003 4.43 0.87
AO0235+164 J0238.6+1636 BLLac 0.940 13.19 0.66
PKS0454-234 J457.1-2325 FSRQ 1.003 13.56 0.24
OJ287 J0855.4+2009 BLLac 0.306 2.48 0.16
WComae J1221.7+28.14 BLLAc 0.102 2.58 0.17
3C273 J1229.1+0202 FSRQ 0.158 8.68 0.38
3C279 J1256.1-0548 FSRQ 0.536 15.69 0.62
PKS1510-089 J1512.7-0905 FSRQ 0.,36 28.67 0.91
J123939+0440 J123939+0440 FSRQ
3c454.3 J2254.0+1609 FSRQ 0.859 24.58 0.82
Fermi Sources: July – December 2008
→ Selection of Blazars → Flux (>300MeV) > 20 10-8 photons.cm-2.s-1 (high state)→ Variability σ2
NXS > 0.15 (Abdo et al, ……..)Selection
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Unbinned analysis with AAFit: candidate source
Time PDF
Fermi gamma-ray light curve for 3C454.3
(Flare’s determination: cf talk at Paris)
(before normalisation)
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Unbinned analysis with AAFit: candidate source
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Unbinned analysis with AAFit:
Source Λ N(3σ) S(3σ) Λ N(5σ) S(5σ) Λ Nsen Ssen
0208 -5.2 1.13 0.0030 -5.5 3.45 0.0077 -5.7 2.82 0.0058
0235 -5.3 0.90 0.0052 -5.3 2.36 0.0014 -5.8 2.78 0.0127
1510 -5.4 0.99 0.0040 -5.2 2.37 0.011 -5.7 2.71 0.0096
3c273 -5.2 0.95 0.0049 -5.3 2.96 0.014 -5.7 2.76 0.011
3c279 -5.3 0.92 0.0040 -5.3 2.54 0.011 -5.7 2.78 0.0098
3c454 -5.3 0.93 0.0053 -5.2 2.39 0.015 -5.7 2.71 0.013
J1239 -5.6 0.89 0.0037 -5.4 1.90 0.0087 -5.8 2.63 0.010
OJ287 -5.4 0.84 0.0047 -5.5 2.23 0.012 -5.8 2.64 0.013
0454 -5.6 0.90 0.0031 -5.4 1.98 0.0074 -5.8 2.63 0.0084
WCom -5.5 0.82 0.0051 -5.6 3.00 0.012 -5.8 2.56 0.014
Expected results for the sensitivity (90% CL) and for the 3(5) σ discovery potential (50% prob)
Flux: GeV.m-2.s
-1
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Unbinned analysis with AAFit: Expected results for the sensitivity (90% CL) and for
the 3(5) σ discovery potential (50% prob)
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Unbinned analysis with AAFit:
2 sources of systematic errors:
- Angular resolution: make worse the angular resolution by a factor 15% applied with a gaussian distribution (cf Aart point source )
Keep the same PDF but change only the PSF for the generation
- Efficiency: make worse the efficiency by a factor 30% change the number of events injected in the sample (gauss(1,0.3))
- Extrapolation 3->5σ ?- Others sources: absolute pointing, …
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Unbinned analysis with AAFit:
Expected results for the sensitivity (90% CL) and for the 3(5) σ discovery potential (50% prob) including the systematic errors
Average effect: Sensititivty: ~1.10 Discovery: ~1.20
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Unbinned analysis with BBFit: fixed source
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Unbinned analysis with BBFit: fixed source
10days
0.1day
No timing
1day
Declination : -40º
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Unbinned analysis with BBFit: fixed source
Declination : -40º
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Unbinned analysis with BBFit: fixed source
Declination : -40º
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Unbinned analysis with BBFit: candidate source
Source 3C454.3
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Unbinned analysis with BBFit: candidate source
Source tχ2 N(3σ) S(3σ) tχ2 N(5σ) S(5σ) tχ2 Nsen Ssen
0208 1.8 3.04 0.0058 2.0 6.45 0.011 2.2 3.99 0.0062
0235 1.8 2.40 0.0102 2.4 6.42 0.020 2.4 3.69 0.011
1510 2.0 2.32 0.0060 2.0 4.98 0.013 2.4 3.58 0.0078
3c273 1.8 2.53 0.0081 2.0 5.58 0.016 2.4 3.95 0.0094
3c279 1.8 2.06 0.0061 2.0 4.84 0.013 2.4 3.58 0.0079
3c454 1.8 2.59 0.011 2.4 6.45 0.019 2.4 3.80 0.011
J1239 2.0 1.39 0.0040 2.0 2.60 0.0076 3.0 3.12 0.0068
OJ287 2.0 1.86 0.0075 2.0 3.97 0.016 3.0 3.56 0.0099
0454 2.0 1.44 0.0034 2.2 3.4 0.0065 2.8 2.96 0.0054
WCom 2.0 1.43 0.0084 1.8 2.90 0.016 3.0 3.41 0.013
1.8: 451 bkg events 2.4: 2748 bkg events2.0: 791 bkg events 3.0: 8702 bkg events
Expected results for the sensitivity (90% CL) and for the 3(5) σ discovery potential (50% prob)
Flux: GeV.m-2.s
-1
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Unbinned analysis with BBFit: candidate source Expected results for the sensitivity (90% CL) and for
the 3(5) σ discovery potential (50% prob)
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Unbinned analysis with BBFit: candidate source Expected results for the sensitivity (90% CL) and for
the 3(5) σ discovery potential (50% prob) including the systematic errors.
Average effect: Sensititivty: ~1.20 Discovery: ~1.15
Same source of systematic errors than the ones used with AAFit: - Ang Res: +gauss(1,0.15) - Efficiency: +gauss(1,0.3) on the injected number of signal events
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Unbinned analysis: comparison AAFit / BBFit
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Unbinned analysis: comparison AAFit / BBFit
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Summary and perspectives:
Unbinned analysis of the Fermi sources in 2008 (~57 days) is (almost) done. Internal close to be
finishedPerspectives:1) Use the time distribution of the data in order to simulate background events and to build the time PDF.
Example: all events reconstructed with the on-line BBFit with at least 2 lines and a fit quality, tchi2<4.0
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Summary and perspectives:
Time variable analysis seems to worked using BBFit or AAFit with the 12L data in
2008Perspectives:2) Extend the analysis to 2009-10 data
Source 3C454.3 gamma-ray light curve from Aug 2008 to Sept 2010
Missing: Data: BBFit-> OKData: interline offset ?MC: on-going, help ?
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Summary and perspectives:
Time variable analysis seems to worked using BBFit or AAFit with the 12L data in
2008Perspectives:2) Extend the analysis to 2009-10 data
Time distribution of the data for 2008-09-10 reconstructed with BBFit (tcosth>0&&tchi2<1.8&&nline>1&&nhit>5)
Missing: Data: BBFit-> OKData: interline offset ?MC: on-going, help ?