Dynamical Rotational Instability at Low [ITAL]T[/ITAL]/[ITAL]W[/ITAL]

Centrella, Joan; New, Kimberly C. B.; Lowe, Lisa L.; Brown, J. David

doi:10.1086/319634

Cited by 129 publications

(165 citation statements)

References 23 publications

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“…However, these stars may be susceptible to the relatively new class of dynamical instability (so-called "low T/|W| instability", e.g. Centrella et al 2001;Watts et al 2003;Saijo & Yoshida 2006;Ou & Tohline 2006;Baiotti et al 2008), whose existence relies on the strong shear flow (Watts et al 2005;Corvino et al 2010). Numerical simulations of binary NSs do indeed indicate that the HMNS develops a bar deformation (e.g.…”

Section: Summary and Discussionmentioning

confidence: 99%

Differentially-rotating neutron star models with a parametrized rotation profile

Galeazzi

Yoshida

Eriguchi

2012

A&A

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We analyze the impact of the rotation law on equilibrium sequences of relativistic differentially-rotating neutron stars in axisymmetry. The maximum allowed mass for each model is strongly affected by the distribution of the angular velocity in the radial direction and by the consequent degree of differential rotation. To study the wide parameter space implied by the choice of the rotation law, we introduce a functional form that generalizes the so-called "j-const. law" adopted in all previous work. We compute equilibrium sequences of differentially rotating stars with a polytropic equation of state starting from the spherically symmetric static case. By analyzing the sequences with decreasing degrees of differential rotation, we find that the maximum value of the ratio T/|W| of rotational kinetic energy to gravitational binding energy, is substantially limited in these cases to a value of 0.128.

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Section: Summary and Discussionmentioning

confidence: 99%

Differentially-rotating neutron star models with a parametrized rotation profile

Galeazzi

Yoshida

Eriguchi

2012

A&A

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“…Recently, a new kind of dynamical rotational nonaxisymmetric instability at a value of β much lower than the classical threshold has been discovered both in numerical and perturbative studies (see, e.g., [17,22,25,[79][80][81][82][83][84][85] and references therein). This low-β instability (making the classical MacLaurin instability a "high"-β instability) appears to amplify nonaxisymmetric modes at points where their pattern speed σ m (the eigenfrequency ω m divided by the azimuthal mode order m) coincides with the local angular velocity of the fluid [22,[81][82][83].…”

Section: Rotation Of the Proto-neutron Starmentioning

confidence: 99%

“…is the dynamical timescale of the rotating star set by the Keplerian angular velocity [22,79]. Since solid-body rotation is the state of lowest rotational energy, neutron stars are very likely to become rigidly rotating within at most a few dissipative timescales during their post-supernova cooling evolution.…”

Section: A the Rotational Barrier In Core Collapsementioning

confidence: 99%

Gravitational wave burst signal from core collapse of rotating stars

et al. 2008

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We present results from detailed general relativistic simulations of stellar core collapse to a protoneutron star, using two different microphysical nonzero-temperature nuclear equations of state as well as an approximate description of deleptonization during the collapse phase. Investigating a wide variety of rotation rates and profiles as well as masses of the progenitor stars and both equations of state, we confirm in this very general setup the recent finding that a generic gravitational wave burst signal is associated with core bounce, already known as type I in the literature. The previously suggested type II (or "multiple-bounce") waveform morphology does not occur. Despite this reduction to a single waveform type, we demonstrate that it is still possible to constrain the progenitor and postbounce rotation based on a combination of the maximum signal amplitude and the peak frequency of the emitted gravitational wave burst. Our models include to sufficient accuracy the currently known necessary physics for the collapse and bounce phase of core-collapse supernovae, yielding accurate and reliable gravitational wave signal templates for gravitational wave data analysis. In addition, we assess the possiblity of nonaxisymmetric instabilities in rotating nascent proto-neutron stars. We find strong evidence that in an iron core-collapse event the postbounce core cannot reach sufficiently rapid rotation to become subject to a classical bar-mode instability. However, many of our postbounce core models exhibit sufficiently rapid and differential rotation to become subject to the recently discovered dynamical instability at low rotation rates.

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“…The j5 models may even reach the threshold of 27% for the high-T /|W | dynamical instability within a few hundred ms of bounce. models already at values of T /|W | of order ∼1% [59,[123][124][125][126]. Hence, this instability is commonly referred to as low-T /|W | instability.…”

Section: Evolution Of the Rotation Rate And Prospects For Rotationmentioning

confidence: 99%

Correlated gravitational wave and neutrino signals from general-relativistic rapidly rotating iron core collapse

et al. 2012

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We present results from a new set of 3D general-relativistic hydrodynamic simulations of rotating iron core collapse. We assume octant symmetry and focus on axisymmetric collapse, bounce, the early postbounce evolution, and the associated gravitational wave (GW) and neutrino signals. We employ a finite-temperature nuclear equation of state, parameterized electron capture in the collapse phase, and a multi-species neutrino leakage scheme after bounce. The latter captures the important effects of deleptonization, neutrino cooling and heating and enables approximate predictions for the neutrino luminosities in the early evolution after core bounce. We consider 12-M and 40-M presupernova models and systematically study the effects of (i) rotation, (ii) progenitor structure, and (iii) postbounce neutrino leakage on dynamics, GW, and, neutrino signals. We demonstrate, that the GW signal of rapidly rotating core collapse is practically independent of progenitor mass and precollapse structure. Moreover, we show that the effects of neutrino leakage on the GW signal are strong only in nonrotating or slowly rotating models in which GW emission is not dominated by inner core dynamics. In rapidly rotating cores, core bounce of the centrifugally-deformed inner core excites the fundamental quadrupole pulsation mode of the nascent protoneutron star. The ensuing global oscillations (f ∼ 700 − 800 Hz) lead to pronounced oscillations in the GW signal and correlated strong variations in the rising luminosities of antineutrino and heavy-lepton neutrinos. We find these features in cores that collapse to protoneutron stars with spin periods 2.5 ms and rotational energies sufficient to drive hyper-energetic core-collapse supernova explosions. Hence, GW or neutrino observations of a core collapse event could deliver strong evidence for or against rapid core rotation. Joint GW + neutrino observations would allow to make statements with high confidence. Our estimates suggest that the GW signal should be detectable throughout the Milky Way by advanced laser-interferometer GW observatories, but a water-Cherenkov neutrino detector would have to be of near-megaton size to observe the variations in the early neutrino luminosities from a core collapse event at 1 kpc.

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Dynamical Rotational Instability at Low [ITAL]T[/ITAL]/[ITAL]W[/ITAL]

Cited by 129 publications

References 23 publications

Differentially-rotating neutron star models with a parametrized rotation profile

Differentially-rotating neutron star models with a parametrized rotation profile

Gravitational wave burst signal from core collapse of rotating stars

Correlated gravitational wave and neutrino signals from general-relativistic rapidly rotating iron core collapse

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