Template-based gravitational-wave echoes search using Bayesian model selection
The ringdown of the gravitational-wave signal from a merger of two black holes has been suggested as a probe of the structure of the remnant compact object, which may be more exotic than a black hole. It has been pointed out that there will be a train of echoes in the late-time ringdown stage for different types of exotic compact objects. In this paper, we present a template-based search methodology using Bayesian statistics to search for echoes of gravitational waves. Evidence for the presence or absence of echoes in gravitational-wave events can be established by performing Bayesian model selection. The Occam factor in Bayesian model selection will automatically penalize the more complicated model that echoes are present in gravitational-wave strain data because of its higher degree of freedom to fit the data. We find that the search methodology was able to identify gravitational-wave echoes with Abedi et al.'s echoes waveform model about 82.3% of the time in simulated Gaussian noise in the Advanced LIGO and Virgo network and about 61.1% of the time in real noise in the first observing run of Advanced LIGO with ≥ 5σ significance. Analyses using this method are performed on the data of Advanced LIGO's first observing run, and we find no statistical significant evidence for the detection of gravitational-wave echoes. In particular, we find < 1σ combined evidence of the three events in Advanced LIGO's first observing run. The analysis technique developed in this paper is independent of the waveform model used, and can be used with different parametrized echoes waveform models to provide more realistic evidence of the existence of echoes from exotic compact objects.
© 2019 American Physical Society. (Received 21 November 2018; published 30 April 2019) The authors acknowledge the generous support from the National Science Foundation in the United States. 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. R. K. L. L. and T. G. F. L. 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 24304317) and the Direct Grant for Research from the Research Committee of the Chinese University of Hong Kong. The authors acknowledge the use of the IUCAA LDG cluster Sarathi for the computational/numerical work. The authors are also grateful for computational resources provided by the LIGO Laboratory and supported by National Science Foundation Grants No. PHY-0757058 and No. PHY-0823459. The authors would like to thank Ajith Parameswaran for reviewing this paper during the LSC internal review. R. K. L. L. would also like to thank Zachary Mark, Rory Smith, Peter T. H. Pang, Ignacio Magana, Alex Nielsen, Ofek Birnholtz and Yanbei Chen for the fruitful conversations with the first author. Figure 2 was generated using the Python package CORNER.PY . This paper carries LIGO Document Number LIGO-P1800319.
Submitted - 1811.07431.pdf
Published - PhysRevD.99.084052.pdf