Constraining the p-mode-g-mode tidal instability with GW170817
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Authors
Colleges, School and Institutes
External organisations
- California Institute of Technology
- Louisiana State University
- Universita degli Studi di Salerno
- Complesso Universitario di Monte S.Angelo
- Monash University
- LIGO Livingston Observatory
- Université Grenoble Alpes
- University of Sannio at Benevento
- Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1, D-14476 Potsdam, Germany
- Institut für Gravitationsphysik (Albert-Einstein-Institut)
- University of Illinois at Urbana-Champaign
- University of Cambridge
- Institution Nikhef National Institute for Subatomic Physics
- Massachusetts Institute of Technology
- Instituto Nacional de Pesquisas Espaciais
- Laboratori Nazionali del Gran Sasso
- Inter-University Centre for Astronomy and Astrophysics India
- Tata Institute of Fundamental Research
- University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
- Università di Pisa
- Sezione INFN di Pisa
- Fundació General de la Universitat de Valencia (FGUV)
- The Australian National University
- Domaine Scientifique de la Doua
- University of Strathclyde
- IN2P3
- University of Oregon
Abstract
We analyze the impact of a proposed tidal instability coupling p modes and g modes within neutron stars on GW170817. This nonresonant instability transfers energy from the orbit of the binary to internal modes of the stars, accelerating the gravitational-wave driven inspiral. We model the impact of this instability on the phasing of the gravitational wave signal using three parameters per star: an overall amplitude, a saturation frequency, and a spectral index. Incorporating these additional parameters, we compute the Bayes factor (lnB_{!pg}^{pg}) comparing our p-g model to a standard one. We find that the observed signal is consistent with waveform models that neglect p-g effects, with lnB_{!pg}^{pg}=0.03_{-0.58}^{+0.70} (maximum a posteriori and 90% credible region). By injecting simulated signals that do not include p-g effects and recovering them with the p-g model, we show that there is a ≃50% probability of obtaining similar lnB_{!pg}^{pg} even when p-g effects are absent. We find that the p-g amplitude for 1.4 M_{⊙} neutron stars is constrained to less than a few tenths of the theoretical maximum, with maxima a posteriori near one-tenth this maximum and p-g saturation frequency ∼70 Hz. This suggests that there are less than a few hundred excited modes, assuming they all saturate by wave breaking. For comparison, theoretical upper bounds suggest ≲10^{3} modes saturate by wave breaking. Thus, the measured constraints only rule out extreme values of the p-g parameters. They also imply that the instability dissipates ≲10^{51} erg over the entire inspiral, i.e., less than a few percent of the energy radiated as gravitational waves.
Details
Original language | English |
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Article number | 061104 |
Journal | Physical Review Letters |
Volume | 122 |
Issue number | 6 |
Publication status | Published - 13 Feb 2019 |