Constraining the p-mode-g-mode tidal instability with GW170817

Research output: Contribution to journalArticlepeer-review

Authors

  • LIGO Scientific Collaboration
  • Virgo Collaboration

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
  • Facebook
  • 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
  • STRATHCLYDE UNIVERSITY
  • 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 languageEnglish
Article number061104
JournalPhysical Review Letters
Volume122
Issue number6
Publication statusPublished - 13 Feb 2019

ASJC Scopus subject areas