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Targeted Sub-threshold Search for Strongly-lensed Gravitational-wave Events

Li, Alvin K. Y. and Lo, Rico K. L. and Sachdev, Surabhi and Li, Tjonnie G. F. and Weinstein, Alan J. (2019) Targeted Sub-threshold Search for Strongly-lensed Gravitational-wave Events. . (Unpublished)

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Strong gravitational lensing of gravitational waves can produce duplicated signals that are separated in time and with different amplitudes. We consider the case in which strong lensing produces identifiable gravitational-wave events together with weaker sub-threshold signals that are hidden in the noise background. We present a search method for the sub-threshold signals using reduced template banks targeting specific confirmed gravitational-wave events. We apply the method to an event from Advanced LIGO's first observing run O1, GW151012. We show that the method is effective in reducing the noise background and hence raising the significance of (near-) sub-threshold triggers. In the case of GW151012, we are able to improve the sensitive distance by 10%−25%. Finally, we present the 10 most significant events for GW151012-like signals in O1. Besides the already confirmed gravitational-wave detections, none of the candidates pass our nominal significance threshold of False-Alarm-Rate ≤ 1/30 days.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Sachdev, Surabhi0000-0002-2432-7070
Li, Tjonnie G. F.0000-0003-4297-7365
Weinstein, Alan J.0000-0002-0928-6784
Additional Information:The authors acknowledge the generous support from the National Science Foundation in the United States. The authors would also like to acknowledge Jonah Kanner for his useful suggestion. RKLL and TGFL would also like to gratefully acknowledge the support from the Croucher Foundation in Hong Kong. The work described in this paper was partially supported by a grant from the Research Grants Council of the Hong Kong (Project No. CUHK 14306218) and the Direct Grant for Research from the Research Committee of the Chinese University of Hong Kong. SS was supported in part by the LIGO Laboratory and in part by the Eberly Research Funds of Penn State, The Pennsylvania State University, University Park, PA 16802, USA. The authors are also grateful for computational resources provided by the LIGO Laboratory and supported by National Science Foundation Grants PHY-0757058 and PHY-0823459. This research has made use of data, software and/or web tools obtained from the Gravitational Wave Open Science Center ( [57], a service of LIGO Laboratory, the LIGO Scientific Collaboration and the Virgo Collaboration. 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. Virgo is funded by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale della Fisica Nucleare (INFN) and the Dutch Nikhef, with contributions by Polish and Hungarian institutes. This paper carries LIGO Document Number LIGO-P1900059.
Funding AgencyGrant Number
Croucher FoundationUNSPECIFIED
Research Grants Council of Hong KongCUHK 14306218
Chinese University of Hong KongUNSPECIFIED
Lithuanian Academy of SciencesUNSPECIFIED
Pennsylvania State UniversityUNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Istituto Nazionale di Fisica Nucleare (INFN)UNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
LIGO DocumentP1900059
Record Number:CaltechAUTHORS:20190501-135950324
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95140
Deposited By: George Porter
Deposited On:01 May 2019 22:12
Last Modified:09 Mar 2020 13:19

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