Time variable analysis

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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

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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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AAFit BBFit

Upgoing events with error estimate β<1º

Upgoing events with nline>1 && nhit>5

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AAFit BBFit

All events with β<1º && Λ>-5.4

All events with nline>1 && nhit>5 && tchi2<1.5

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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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AAFit BBFit


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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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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AAFit BBFit


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)


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Stability of the fit 35σ

0.1 day

No timing

No timing

1 day3 days

84 days


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Number of events needed for a 3σ discovery

Conversion Nevent Flux with the visibility, effective area and live time


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


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Declination : -40º


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Declination : -40º


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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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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:

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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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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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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10days

0.1day

No timing

1day

Declination : -40º

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Declination : -40º

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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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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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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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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 ?

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Time variable analysis

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