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Analytical model for gravitational-wave echoes from spinning remnants

Maggio, Elisa and Testa, Adriano and Bhagwat, Swetha and Pani, Paolo (2019) Analytical model for gravitational-wave echoes from spinning remnants. Physical Review D, 100 (6). Art. No. 064056. ISSN 2470-0010. doi:10.1103/physrevd.100.064056.

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Gravitational-wave echoes in the postmerger signal of a binary coalescence are predicted in various scenarios, including near-horizon quantum structures, exotic states of matter in ultracompact stars, and certain deviations from general relativity. The amplitude and frequency of each echo is modulated by the photon-sphere barrier of the remnant, which acts as a spin- and frequency-dependent high-pass filter, decreasing the frequency content of each subsequent echo. Furthermore, a major fraction of the energy of the echo signal is contained in low-frequency resonances corresponding to the quasinormal modes of the remnant. Motivated by these features, in this work we provide an analytical gravitational-wave template in the low-frequency approximation describing the postmerger ringdown and the echo signal of a spinning ultracompact object. Besides the standard ringdown parameters, the template is parametrized in terms of only two physical quantities: the reflectivity coefficient and the compactness of the remnant. We discuss novel effects related to the spin and to the complex reflectivity, such as a more involved modulation of subsequent echoes, the mixing of two polarizations, and the ergoregion instability in the case of perfectly reflecting spinning remnants. Finally, we compute the errors in the estimation of the template parameters with current and future gravitational-wave detectors using a Fisher matrix framework. Our analysis suggests that models with almost perfect reflectivity can be excluded/detected with current instruments, whereas probing values of the reflectivity smaller than 80% at the 3σ confidence level requires future detectors (Einstein Telescope, Cosmic Explorer, LISA). The template developed in this work can easily be implemented to perform a matched-filter based search for echoes and to constrain models of exotic compact objects.

Item Type:Article
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URLURL TypeDescription Paper
Maggio, Elisa0000-0002-1960-8185
Pani, Paolo0000-0003-4443-1761
Additional Information:© 2019 American Physical Society. Received 10 July 2019; published 26 September 2019. We are indebted to Emanuele Berti, Gregorio Carullo, Walter Del Pozzo, Antoine Klein, Simone Mastrogiovanni, and John Veitch for interesting discussions and correspondence, and to Xin Shuo for highlighting a typo in Eq. (25). We acknowledge support provided under the European Union’s H2020 ERC, Starting Grant Agreement No. DarkGRA-757480, and by the Amaldi Research Center funded by the MIUR program “Dipartimento di Eccellenza” (CUP: B81I18001170001). A. T. is also grateful for the support provided by the Walter Burke Institute for Theoretical Physics.
Group:Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
European Research Council (ERC)757480
Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR)B81I18001170001
Walter Burke Institute for Theoretical Physics, CaltechUNSPECIFIED
Issue or Number:6
Record Number:CaltechAUTHORS:20190926-161703678
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98891
Deposited By: Tony Diaz
Deposited On:26 Sep 2019 23:23
Last Modified:16 Nov 2021 17:42

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