Search for ‘unmodeled’ astrophysical sources by GEO600
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Transcript of Search for ‘unmodeled’ astrophysical sources by GEO600
Search for ‘unmodeled’ astrophysical sources by
GEO600
Soma Mukherjee
AEI-MPG, GDAW
Feb. 22, 2002
http://www.aei.mpg.de/~soma/burst.html
Soma Mukherjee 22.02.02
Some facts :• Burst document http://www.aei.mpg.de/~soma/burst_plan.ps circulated in October,
2001• Group formed in November 2001• First telecon took place in December, 2001• Task table formed with definite goals.• Plans include :
a. Event list exchange with LIGO for the coincidence data run.
b. Post-processing with GEO’s own burst triggers.
Soma Mukherjee 22.02.02
Current pipeline design
Read Frames :GEO++
FrameInputStream Class.
ALL channels.
Write triggers onto The database.
GEO++ database IO classes.
Remove lines by MBLT :
ALL channels.
Excess power Statistics.
LAL codes
MPI SHELL
Soma Mukherjee 22.02.02
Current status :• The pipeline will be in operation at the Hannover
Beowulf cluster.• Will run within the GEO++ framework.• Frame reading utility in place.• Database uses LIGO database table to write triggers.• Median Based Line Tracker algorithm C++ code
complete, being tested.• Implementation of LAL ExcessPower statistics
algorithm in the GEO++ environment is in progress.
Soma Mukherjee 22.02.02
Generation of Vetoes :
• Vetoes will be generated by comparing the output of the filter with the information written in the DCR database.
• Preferred strategy : Coincidence, provided the false alarm in the auxiliary channels is low enough.
• Bursts that survive this veto will constitute our ‘event list’.
Soma Mukherjee 22.02.02
Future expansion :• More features :
A. Line removal : * Kalman filter, coherent line
removal, Finn_Huq cross channel regression
method.
B. Filters :
* PSDChange, ALF algorithm, Anderson+Bala’s track search
algorithm.
Soma Mukherjee 22.02.02
Post processing :
• Cluster Analysis : Classification of bursts in terms of
their duration, strength, shape, largest 50% of wavelet coefficients etc.
Proposed methods : (1) Exploratory (2) Non-parametric hierarchical cluster analysis followed by validation of
classification.
• Monte Carlo studies and Inference :
This will involve simulation of test signals bearing approximate characteristics of bursts of astrophysical origin, injection of the same in simulated detector noise and evaluation of the detection efficiency and false alarm rate of the detection pipeline.
Soma Mukherjee 22/02/02
Immediate goals :• Implementation of MBLT and LAL
ExcessPower codes.
• Having a run over all channels for a week’s worth of data.
• Look for clusters with start_time, central_freq, SNR, highest 10 wavelet coefficients.
Soma Mukherjee 22.02.02
LSC and GEO :
• People from AEI involved in the LIGO BUL group : Soma, Soumya
• Which subgroup ? External Triggers.
• What’s going on ? Student’s t-test algorithm (Finn-Mohanty-Romano) for association of Gamma
Ray Bursts and Gravitational Waves is being coded. (Mohanty+Rakhola)
Studies of non-stationarity being made on the ‘playground’ data identified by the LSC BUL group. (Soma)
Soma Mukherjee 22.02.02
Participation of GEO in NDAS
• Relevant codes obtained from Szabi.
• Account set up at Hannover with Sathya in charge.
• As of now, only PEM channels will be merged.
• Work in progress.
Soma Mukherjee 22.02.02
Issues open to discussion
• Should vetoing be inside the burst pipeline or should it be a part of post-processing ?
• Will GEO set up an infrastructure for astronomical triggers ?
• Should the pipeline involve only h(t) or all channels ?
• What parameters are of astrophysical interest for burst clustering problems ?
Soma Mukherjee 22.02.02
Top Priority :
Implementation of LAL ExcessPower Statistics algorithm.