Detecting very long-lived gravitational-wave transients lasting hours to weeks
We explore the possibility of very long-lived gravitational-wave transients (and detector artifacts) lasting hours to weeks. Such very long signals are both interesting in their own right and as a potential source of systematic error in searches for persistent signals, e.g., from a stochastic gravitational-wave background. We review possible mechanisms for emission on these time scales and discuss computational challenges associated with their detection: namely, the substantial volume of data involved in a search for very long transients can require vast computer memory and processing time. These computational difficulties can be addressed through a form of data compression known as coarse graining, in which information about narrow frequency bins is discarded in order to reduce the computational requirements of a search. Using data compression, we demonstrate an efficient radiometer (cross-correlation) algorithm for the detection of very long transients. In the process, we identify features of a very long transient search (related to the rotation of the Earth) that make it more complicated than a search for shorter transient signals. We implement suitable solutions.
© 2015 American Physical Society. Received 26 January 2015; published 18 May 2015. We thank Joe Romano for helpful discussion on coarse graining, Vladimir Dergachev for discussion on intermittent pulsars, and David Keitel for carefully reading and commenting on an earlier version of the manuscript. E. T. was a member of the LIGO Laboratory, supported by funding from United States National Science Foundation. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under cooperative agreement PHY-0757058. V.M.'s work was supported by NSF Grant No. PHY1204944. N. C.'s work was supported by NSF Grant No. PHY-1204371. This is LIGO document P1400256.
Submitted - 1501.06648v3.pdf
Published - PhysRevD.91.104021.pdf