One-armed spiral instability in neutron star mergers and its detectability in gravitational waves

Radice, David; Bernuzzi, Sebastiano; Ott, Christian D.

doi:10.1103/physrevd.94.064011

Cited by 81 publications

(97 citation statements)

References 72 publications

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“…In turn, this implies that there is some degree of degener-acy with the nuclear EOS when inferring the latter from the post-merger peak GW frequency. We find that the one-arm instability we discovered in eccentric NS mergers (including those with spin) [40][41][42] and studied in select non-spinning quasicircular mergers [43,44], also operates in quasicircular mergers with spin, though the correlation between the strength of the one-arm mode and the pre-merger spin magnitude is not strong. In particular, we find that the strongest one-arm mode develops for an intermediate value of NS spin that we consider.…”

Section: Introductionmentioning

confidence: 69%

Binary neutron star mergers: Effects of spin and post-merger dynamics

et al. 2019

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Spin can have significant effects on the electromagnetic transients accompanying binary neutron star mergers. The measurement of spin can provide important information about binary formation channels. In the absence of a strong neutron star spin prior, the degeneracy of spin with other parameters leads to significant uncertainties in their estimation, in particular limiting the power of gravitational waves to place tight constraints on the nuclear equation of state. Thus detailed studies of highly spinning neutron star mergers are essential to understand all aspects of multimessenger observation of such events. We perform a systematic investigation of the impact of neutron star spin-considering dimensionless spin values up to aNS = 0.33-on the merger of equal mass, quasicircular binary neutron stars using fully general-relativistic simulations. We find that the peak frequency of the post-merger gravitational wave signal is only weakly influenced by the neutron star spin, with cases where the spin is aligned (anti-aligned) with the orbital angular momentum giving slightly lower (higher) values compared to the irrotational case. We find that the one-arm instability arises in a number of cases, with some dependence on spin. Spin has a pronounced impact on the mass, velocity, and angular distribution of the dynamical ejecta, and the mass of the disk that remains outside the merger remnant. We discuss the implications of these findings on anticipated electromagnetic signals, and on constraints that have been placed on the equation of state based on multimessenger observations of GW170817.

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Section: Introductionmentioning

confidence: 69%

Binary neutron star mergers: Effects of spin and post-merger dynamics

et al. 2019

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“…At timescales ∼10 − 20 ms corresponding tot ∼ 1000 − 2000 (M ∼ 2.7M ) the remnant has either collapsed (shortlived) or dissipated most of its energy via GWs. There is no significant GW emission at timescales τ 100 ms [29,76] (see also Appendix B).…”

Section: Nrpm Modelmentioning

confidence: 99%

“…These frequencies have been erroneously interpreted as physical convective modes [115], which are instead not developed on these timescales even using a microphysical EOS. A careful inspection of the dynamics and multipolar waveform reveals instead physical spiral modes with m = 1 geometry [29,49,119,120]. The GW frequency of the mode is f 1 = f 2 /2 and could be added to NRPM model [49], but it corresponds to a weak GW emission [29].…”

Section: Appendix A: Quasiuniversal Relationsmentioning

confidence: 99%

“…KiloHertz GWs contain the imprint of the merger remnant dynamics. The main signature is a short GW transient peaking at a few characteristic frequencies, the dominant one being associated with twice the rotation frequency of the remnant NS at f 2 > f mrg [16,[21][22][23][24][25][26][27][28][29][30]. The transient is more luminous for short-lived remnant than for longlived; an absolute upper limit to the energy per unit mass is 0.126( M 2.8M ) M c 2 , where M is the binary mass [12].…”

Section: Introductionmentioning

confidence: 99%

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Kilohertz gravitational waves from binary neutron star remnants: Time-domain model and constraints on extreme matter

et al. 2019

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The remnant star of a neutron star merger is an anticipated loud source of kiloHertz gravitational waves that conveys unique information on the equation of state of hot matter at extreme densities. Observations of such signals are hampered by the photon shot noise of ground-based interferometers and pose a challenge for gravitational-wave astronomy. We develop an analytical time-domain waveform model for postmerger signals informed by numerical relativity simulations. The model completes effective-one-body waveforms for quasi-circular nonspinning binaries in the kiloHertz regime. We show that a template-based analysis can detect postmerger signals with a minimal signal-to-noise ratios (SNR) of 8, corresponding to GW170817-like events for third-generation interferometers. Using Bayesian model selection and the complete inspiral-merger-postmerger waveform model it is possible to infer whether the merger outcome is a prompt collapse to a black hole or a remnant star. In the latter case, the radius of the maximum mass (most compact) nonrotating neutron star can be determined to kilometer precision. We demonstrate the feasibility of inferring the stiffness of the equation of state at extreme densities using the quasiuniversal relations deduced from numerical-relativity simulations.

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“…Results The key dynamical feature of relevance here is the development of spiral arms in the remnant [56][57][58][59][60][61][62][63][64]. The hydrodynamic instability is monitored by a decomposition in Fourier modes e −imφ of the Eulerian rest-mass density on the equatorial plane (see Eq.…”

Section: Introductionmentioning

confidence: 99%

Spiral-wave Wind for the Blue Kilonova

Nedora

Bernuzzi

Radice

et al. 2019

ApJL

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The AT2017gfo kilonova counterpart of the binary neutron star merger event GW170817 was characterized by an early-time bright peak in optical and UV bands. Such blue kilonova is commonly interpreted as a signature of weak r-process nucleosynthesis in a fast expanding wind whose origin is currently debated. Numerical-relativity simulations with microphysical equations of state, approximate neutrino transport, and turbulent viscosity reveal a new mechanism that can power the blue kilonova. Spiral density waves in the remnant generate a characteristic wind of mass ∼10 −2 M and velocity ∼0.2c. The ejected material has electron fraction mostly distributed above 0.25 being partially reprocessed by hydrodynamic shocks in the expanding arms. The combination of dynamical ejecta and spiral-wave wind can account for solar system abundances of r-process elements and early-time observed light curves.PACS numbers: 04.25.D-, 04.30.Db, 95.30.Sf, 95.30.Lz, 97.60.Jd arXiv:1907.04872v1 [astro-ph.HE]

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One-armed spiral instability in neutron star mergers and its detectability in gravitational waves

Cited by 81 publications

References 72 publications

Binary neutron star mergers: Effects of spin and post-merger dynamics

Binary neutron star mergers: Effects of spin and post-merger dynamics

Kilohertz gravitational waves from binary neutron star remnants: Time-domain model and constraints on extreme matter

Spiral-wave Wind for the Blue Kilonova

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