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.