Pre-print draft: arXiv:0901.3762
Journal: The Classical and Quantum Gravity, Volume 26, Issue 15, id. 155009 (2009).
Enhancing the Capabilities of LIGO Time-Frequency Plane Searches Through Clustering
Rubab Khan,
Shourov Chatterji
One class of gravitational wave signals LIGO is searching for consists
of short duration bursts of unknown waveforms. Potential sources
include core collapse supernovae, gamma ray burst progenitors, and
mergers of binary black holes or neutron stars. We present a
density-based clustering algorithm to improve the performance of
time-frequency searches for such gravitational-wave bursts when they
are extended in time and/or frequency, and not sufficiently well known
to permit matched filtering. We have implemented this algorithm as an
extension to the QPipeline, a gravitational-wave data analysis
pipeline for the detection of bursts, which currently determines the
statistical significance of events based solely on the peak
significance observed in minimum uncertainty regions of the
time-frequency plane. Density based clustering improves the
performance of such a search by considering the aggregate significance
of arbitrarily shaped regions in the time-frequency plane and
rejecting the isolated minimum uncertainty features expected from the
background detector noise. In this paper, we present test results for
simulated signals and demonstrate that density based clustering
improves the performance of the QPipeline for signals extended in time
and/or frequency.
The authors are grateful for the support of the United States National Science Foundation under cooperative agreement PHY-04-57528, California Institute of Technology, and Columbia University in the City of New York. We are grateful to the LIGO Scientific collaboration for their support. We are indebted to many of our colleagues for frequent and fruitful discussion. In particular, we'd like to thank Albert Lazzarini for his valuable suggestions regarding this project, and Luca Matone, Zsuzsa Marka, Sharmila Kamat, Jameson Rollins, Peter Kalmus, John Dwyer, Patrick Sutton, Eirini Messeritaki, and Szabolcs Marka for their thoughtful comments on the manuscript. The authors gratefully acknowledge the LIGO Scientific Collaboration hardware injection team for providing the data used in Figures 1 and 2. We gratefully acknowledge the contributions of all the software developers and programmers in the broader scientific community without whose incremental achievements over many decades we would not be able to reach this point where implementing this project has become possible. The authors gratefully acknowledge the support of the United States National Science Foundation for the construction and operation of the LIGO Laboratory and the Particle Physics and Astronomy Research Council of the United Kingdom, the Max-Planck-Society and the State of Niedersachsen / Germany for support of the construction and operation of the GEO600 detector. The authors also gratefully acknowledge the support of the research by these agencies and by the Australian Research Council, the Natural Sciences and Engineering Research Council of Canada,the Council of Scientific and Industrial Research of India, the Department of Science and Technology of India, the Spanish Ministerio de Educaciony Ciencia, The National Aeronautics and Space Administration, the John Simon Guggenheim Foundation, the Alexander von Humboldt Foundation,the Leverhulme Trust, the David and Lucile Packard Foundation, the Research Corporation, and the Alfred P. Sloan Foundation. The LIGO Observatories were constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation under cooperative agreement PHY-9210038. The LIGO Laboratory operates under cooperative agreement PHY-0107417. This document has been assigned LIGO document number LIGO-P070041-01-Z.