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Generic searches for alternative gravitational wave polarizations with networks of interferometric detectors

Pang, Peter T. H. and Lo, Rico K. L. and Wong, Isaac C. F. and Li, Tjonnie G. F. and Van Den Broeck, Chris (2020) Generic searches for alternative gravitational wave polarizations with networks of interferometric detectors. Physical Review D, 101 (10). Art. No. 104055. ISSN 2470-0010. doi:10.1103/physrevd.101.104055.

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The detection of gravitational wave signals by Advanced LIGO and Advanced Virgo enables us to probe the polarization content of gravitational waves. In general relativity, only tensor modes are present, while in a variety of alternative theories one can also have vector or scalar modes. Recently test were performed which compared Bayesian evidences for the hypotheses that either purely tensor, purely vector, or purely scalar polarizations were present. Indeed, with only three detectors in a network and allowing for mixtures of tensor polarizations and alternative polarization states, it is not possible to identify precisely which nonstandard polarizations might be in the signal and by what amounts. However, we demonstrate that one can still infer whether, in addition to tensor polarizations, alternative polarizations are present in the first place, irrespective of the detailed polarization content. We develop two methods to do this for sources with electromagnetic counterparts, both based on the so-called null stream. Apart from being able to detect mixtures of tensor and alternative polarizations, these have the added advantage that no waveform models are needed, and signals from any kind of transient source with known sky position can be used. Both formalisms allow us to combine information from multiple sources so as to arrive at increasingly more stringent bounds. For now we apply these on the binary neutron star signal GW170817, showing consistency with the tensor-only hypothesis with p-values of 0.315 and 0.790 for the two methods.

Item Type:Article
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URLURL TypeDescription Paper
Pang, Peter T. H.0000-0001-7041-3239
Lo, Rico K. L.0000-0003-1561-6716
Li, Tjonnie G. F.0000-0003-4297-7365
Additional Information:© 2020 American Physical Society. Received 18 March 2020; accepted 13 May 2020; published 26 May 2020. We are grateful to the anonymous referee, whose careful reading of the manuscript helped us to greatly improve the presentation of the paper. P. T. H. P. and C. V. D. B. are supported by the research program of the Netherlands Organization for Scientific Research (NWO). I. C. F. W. and T. G. F. L. are partially supported by grants from the Research Grants Council of the Hong Kong (Projects No. 24304317 and No. 14306419) and Research Committee of the Chinese University of Hong Kong. R. K. L. L. and T. G. F. L. would also like to gratefully acknowledge the support from the Croucher Foundation in Hong Kong. This research has made use of data, software and/or web tools obtained from the Gravitational Wave Open Science Center (, a service of LIGO Laboratory, the LIGO Scientific Collaboration and the Virgo Collaboration. LIGO is funded by the U.S. National Science Foundation. 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.
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Research Grants Council of the Hong Kong Special Administrative Region of China24304317
Research Grants Council of the Hong Kong Special Administrative Region of China14306419
Chinese University of Hong KongUNSPECIFIED
Croucher FoundationUNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Istituto Nazionale di Fisica Nucleare (INFN)UNSPECIFIED
Issue or Number:10
Record Number:CaltechAUTHORS:20200526-132732443
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103458
Deposited By: Tony Diaz
Deposited On:26 May 2020 20:35
Last Modified:16 Nov 2021 18:21

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