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Gerosa Davide - One of the best experts on this subject based on the ideXlab platform.
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A taxonomy of black-hole binary spin precession and Nutation
2021Co-Authors: Gangardt Daria, Steinle Nathan, Kesden Michael, Gerosa Davide, Stoikos EvangelosAbstract:Binary black holes with misaligned spins will generically induce both precession and Nutation of the orbital angular momentum $\bf{L}$ about the total angular momentum $\bf{J}$. These phenomena modulate the phase and amplitude of the gravitational waves emitted as the binary inspirals to merger. We introduce a "taxonomy" of binary black-hole spin precession that encompasses all the known phenomenology, then present five new phenomenological parameters that describe generic precession and constitute potential building blocks for future gravitational waveform models. These are the precession amplitude $\langle\theta_L\rangle$, the precession frequency $\langle \Omega_L\rangle$, the Nutation amplitude $\Delta\theta_L$, the Nutation frequency $\omega$, and the precession-frequency variation $\Delta\Omega_L$. We investigate the evolution of these five parameters during the inspiral and explore their statistical properties for sources with isotropic spins. In particular, we find that Nutation of $\bf{L}$ is most prominent for binaries with high spins ($\chi \gtrsim 0.5$) and moderate mass ratios ($q \sim 0.6$).Comment: 14 pages, 6 figures, 1 tabl
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Wide Nutation: binary black-hole spins repeatedly oscillating from full alignment to full anti-alignment
'Organisation for Economic Co-Operation and Development (OECD)', 2019Co-Authors: Gerosa Davide, Kesden Michael, Lima Alicia, Berti Emanuele, Sperhake Ulrich, O'shaughnessy RichardAbstract:Within the framework of 2PN black-hole binary spin precession, we explore configurations where one of the two spins oscillates from being completely aligned with the orbital angular momentum to being completely anti-aligned with it during a single precession cycle. This "wide Nutation" is the extreme limit of the generic phenomenon of spin Nutation in black-hole binaries. Crucially, wide Nutation happens on the short precession time scale and it is not a secular effect due to gravitational-wave radiation reaction. The spins of these binaries, therefore, flip repeatedly as one of these special configurations is entered. Binaries with total mass $M$, mass ratio $q$, and dimensionless spin $\chi_1$ ($\chi_2$) of the more (less) massive black hole are allowed to undergo wide Nutation at binary separations $r \leq r_{\rm wide} \equiv [(q \chi_2 - \chi_1)/(1-q)]^2 M$. Sources that are more likely to nutate widely have similar masses and effective spins close to zero
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Wide Nutation: binary black-hole spins repeatedly oscillating from full alignment to full anti-alignment
'AIP Publishing', 2019Co-Authors: Gerosa Davide, Kesden Michael, Lima Alicia, Berti Emanuele, Sperhake Ulrich, O’shaughnessy RichardAbstract:Within the framework of 2PN black-hole binary spin precession, we explore configurations where one of the two spins oscillates from being completely aligned with the orbital angular momentum to being completely anti-aligned with it during a single precession cycle. This wide Nutation is the extreme limit of the generic phenomenon of spin Nutation in black-hole binaries. Crucially, wide Nutation happens on the short precession time scale and it is not a secular effect due to gravitational-wave radiation reaction. The spins of these binaries, therefore, flip repeatedly as one of these special configurations is entered. Binaries with total mass M, mass ratio q, and dimensionless spin Χ_1 (χ_2) of the more (less) massive black hole are allowed to undergo wide Nutation at binary separations r ⩽ r_(wide) ≡ [(qχ_2−χ_1)/(1−q)]^2M. Sources that are more likely to nutate widely have similar masses and effective spins close to zero
Nicolis Stam - One of the best experts on this subject based on the ideXlab platform.
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Nutation magnétique émergente
'Springer Science and Business Media LLC', 2021Co-Authors: Thibaudeau Pascal, Nicolis StamAbstract:International audienceNutation has been recognized as of great significance for spintronics; but justifying its presence has proven to be a hard problem, since overdamping has long been assumed to wash out its effects. In this paper we show that Nutation can be understood as emerging from a systematic expansion of a kernel that describes the history of the interaction of a magnetic moment with a bath of colored noise. The parameter of the expansion is the ratio of the colored noise timescale to the precession period. In the process we obtain the Gilbert damping from the same expansion. We recover the known results, when the coefficients of the two terms are proportional to one another, in the white noise limit; and show how colored noise leads to situations where this simple relation breaks down, but what replaces it can be understood by the appropriate generalization of the fluctuation–dissipation theorem. Numerical simulations of the stochastic equations support the analytic approach. In particular we find that the equilibration time is about an order of magnitude longer than the timescale set by the colored noise for a wide range of values of the latter and we can identify the presence of Nutation in the non-uniform way the magnetization approaches equilibrium
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Emerging magnetic Nutation
'Springer Science and Business Media LLC', 2021Co-Authors: Thibaudeau Pascal, Nicolis StamAbstract:International audienceNutation has been recognized as of great significance for spintronics; but justifying its presence has proven to be a hard problem. In this paper, we show that Nutation can be understood as emerging from a systematic expansion of a kernel that describes the history of the interaction of a magnetic moment with a bath of colored noise. The parameter of the expansion is the ratio of the colored noise timescale to the precession period. In the process we obtain the Gilbert damping from the same expansion. We recover the known results, when the coefficients of the two terms are proportional to one another, in the white noise limit; and show how colored noise leads to situations where this simple relation breaks down, but what replaces it can be understood by the appropriate generalization of the fluctuation–dissipation theorem. Numerical simulations of the stochastic equations support the analytic approach. high temperature limitIn particular, we find that the equilibration time is about an order of magnitude longer than the timescale set by the colored noise for a wide range of values of the latter and we can identify the presence of Nutation in the non-uniform way the magnetization approaches equilibrium.[graphic not available: see fulltext][graphic not available: see fulltext
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Emerging magnetic Nutation
'Springer Science and Business Media LLC', 2021Co-Authors: Thibaudeau Pascal, Nicolis StamAbstract:Nutation has been recognized as of great significance for spintronics; but justifying its presence has proven to be a hard problem. In this paper we show that Nutation can be understood as emerging from a systematic expansion of a kernel that describes the history of the interaction of a magnetic moment with a bath of colored noise. The parameter of the expansion is the ratio of the colored noise timescale to the precession period. In the process we obtain the Gilbert damping from the same expansion. We recover the known results, when the coefficients of the two terms are proportional to one another, in the white noise limit; and show how colored noise leads to situations where this simple relation breaks down, but what replaces it can be understood by the appropriate generalization of the fluctuation--dissipation theorem. Numerical simulations of the stochastic equations support the analytic approach. In particular we find that the equilibration time is about an order of magnitude longer than the timescale set by the colored noise for a wide range of values of the latter and we can identify the presence of Nutation in the non-uniform way the magnetization approaches equilibrium.Comment: 7 pages, 2 figure
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Nutation Wave as a Platform for Ultrafast Spin Dynamics in Ferromagnets
'AIP Publishing', 2020Co-Authors: Makhfudz Imam, Olive Enrick, Nicolis StamAbstract:5+5 pages. Comments are welcomeInternational audienceThe inertia term becomes relevant for the magnetization dynamics of ferromagnets at short time scales and leads to Nutation motion of the magnetization vector. In the simplest model, of a Heisenberg spin chain with isotropic spin-exchange interaction, the occurrence of a "Nutation wave" is analytically demonstrated and numerically confirmed. The corresponding excitation spectrum describes relativistic massive particles. The single-particle excitation, the "nutaton", acts like the Higgs boson with respect to an emergent topological gauge field. This spin excitation would appear as a peak in the spectrum of the scattering structure factor from inelastic neutron scattering experiments. The high frequency and speed of the Nutation wave can open new paths towards new ways of realizing ultrafast spin dynamics
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Nutation Wave as a Platform for Ultrafast Spin Dynamics in Ferromagnets
HAL CCSD, 2019Co-Authors: Makhfudz Imam, Olive Enrick, Nicolis StamAbstract:5+5 pages. Comments are welcomeThe inertia term becomes relevant for the magnetization dynamics of ferromagnets at short time scales and leads to Nutation motion of the magnetization vector. In the simplest model, of a Heisenberg spin chain with isotropic spin-exchange interaction, the occurrence of a "Nutation wave" is analytically demonstrated and numerically confirmed. The corresponding excitation spectrum describes relativistic massive particles. The single-particle excitation, the "nutaton", acts like the Higgs boson with respect to an emergent topological gauge field. This spin excitation would appear as a peak in the spectrum of the scattering structure factor from inelastic neutron scattering experiments. The high frequency and speed of the Nutation wave can open new paths towards new ways of realizing ultrafast spin dynamics
Kesden Michael - One of the best experts on this subject based on the ideXlab platform.
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A taxonomy of black-hole binary spin precession and Nutation
2021Co-Authors: Gangardt Daria, Steinle Nathan, Kesden Michael, Gerosa Davide, Stoikos EvangelosAbstract:Binary black holes with misaligned spins will generically induce both precession and Nutation of the orbital angular momentum $\bf{L}$ about the total angular momentum $\bf{J}$. These phenomena modulate the phase and amplitude of the gravitational waves emitted as the binary inspirals to merger. We introduce a "taxonomy" of binary black-hole spin precession that encompasses all the known phenomenology, then present five new phenomenological parameters that describe generic precession and constitute potential building blocks for future gravitational waveform models. These are the precession amplitude $\langle\theta_L\rangle$, the precession frequency $\langle \Omega_L\rangle$, the Nutation amplitude $\Delta\theta_L$, the Nutation frequency $\omega$, and the precession-frequency variation $\Delta\Omega_L$. We investigate the evolution of these five parameters during the inspiral and explore their statistical properties for sources with isotropic spins. In particular, we find that Nutation of $\bf{L}$ is most prominent for binaries with high spins ($\chi \gtrsim 0.5$) and moderate mass ratios ($q \sim 0.6$).Comment: 14 pages, 6 figures, 1 tabl
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Wide Nutation: binary black-hole spins repeatedly oscillating from full alignment to full anti-alignment
'Organisation for Economic Co-Operation and Development (OECD)', 2019Co-Authors: Gerosa Davide, Kesden Michael, Lima Alicia, Berti Emanuele, Sperhake Ulrich, O'shaughnessy RichardAbstract:Within the framework of 2PN black-hole binary spin precession, we explore configurations where one of the two spins oscillates from being completely aligned with the orbital angular momentum to being completely anti-aligned with it during a single precession cycle. This "wide Nutation" is the extreme limit of the generic phenomenon of spin Nutation in black-hole binaries. Crucially, wide Nutation happens on the short precession time scale and it is not a secular effect due to gravitational-wave radiation reaction. The spins of these binaries, therefore, flip repeatedly as one of these special configurations is entered. Binaries with total mass $M$, mass ratio $q$, and dimensionless spin $\chi_1$ ($\chi_2$) of the more (less) massive black hole are allowed to undergo wide Nutation at binary separations $r \leq r_{\rm wide} \equiv [(q \chi_2 - \chi_1)/(1-q)]^2 M$. Sources that are more likely to nutate widely have similar masses and effective spins close to zero
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Wide Nutation: binary black-hole spins repeatedly oscillating from full alignment to full anti-alignment
'AIP Publishing', 2019Co-Authors: Gerosa Davide, Kesden Michael, Lima Alicia, Berti Emanuele, Sperhake Ulrich, O’shaughnessy RichardAbstract:Within the framework of 2PN black-hole binary spin precession, we explore configurations where one of the two spins oscillates from being completely aligned with the orbital angular momentum to being completely anti-aligned with it during a single precession cycle. This wide Nutation is the extreme limit of the generic phenomenon of spin Nutation in black-hole binaries. Crucially, wide Nutation happens on the short precession time scale and it is not a secular effect due to gravitational-wave radiation reaction. The spins of these binaries, therefore, flip repeatedly as one of these special configurations is entered. Binaries with total mass M, mass ratio q, and dimensionless spin Χ_1 (χ_2) of the more (less) massive black hole are allowed to undergo wide Nutation at binary separations r ⩽ r_(wide) ≡ [(qχ_2−χ_1)/(1−q)]^2M. Sources that are more likely to nutate widely have similar masses and effective spins close to zero
T V Gudkova - One of the best experts on this subject based on the ideXlab platform.
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on models of mars interior and amplitudes of forced Nutations 2 the effects of liquid core and mantle elasticity
Physics of the Earth and Planetary Interiors, 2009Co-Authors: S M Molodensky, V N Zharkov, T V GudkovaAbstract:Abstract The numerical modeling of Mars’ forced Nutation of the real Mars’ model with a radially heterogeneous, compressible, self-gravitating liquid core and elastic mantle is performed. Effects of three-axiality of Mars’ figure are taken into account to compute values for the periods of free core Nutation (FCN) and the amplitudes of forced Nutations. The effects of the liquid core for different models are of the order of few percents for the prograde semi-annual component and of the order of 10–15% for the semi-annual retrograde component. The absolute values of these effects are of the order of 5–20 ms of arc (mas) and 1–3 mas, respectively. Taking into account, that the modern accuracy of VLBI measurements for the case of the Earth is of the order of 0.02 mas, we see, that important results about Mars’ internal structure may be obtained even if the accuracy of Mars’ Nutational measurements 1–2 order of magnitude less than accuracy for the Earth. The effects of the shear stress relaxation during long time intervals are studied: the corrections to the Nutational amplitudes for prograde semi-annual component are between 8.93 and 9.8, for retrograde semi-annual component are between −4.81 and −8.2 ms of arc, and the period of free core Nutation is varied in the limits between 257.2 and 295.8 Earth's solar days. The differences exceed significantly the errors of Mars’ Nutational components measurements, and, consequently, these measurements can give new important information about Martian mantle rheology. The possibilities of inferring properties of the interior structure of Mars based on the measurements of its rotation are discussed.
Veronique Dehant - One of the best experts on this subject based on the ideXlab platform.
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the coupling between inertial and rotational eigenmodes in planets with liquid cores
Geophysical Journal International, 2019Co-Authors: S A Triana, Jeremy Rekier, Antony Trinh, Veronique DehantAbstract:The Earth is a rapidly rotating body. The centrifugal pull makes its shape resemble a flattened ellipsoid and Coriolis forces support waves in its fluid core, known as inertial waves. These waves can lead to global oscillations, or modes, of the fluid. Periodic variations of the Earth's rotation axis (Nutations) can lead to an exchange of angular momentum between the mantle and the fluid core and excite these inertial modes. In addition to viscous torques that exist regardless of the shape of the boundaries, the small flattening of the core-mantle boundary (CMB) allows inertial modes to exert pressure torques on the mantle. These torques effectively couple the rigid-body dynamics of the Earth with the fluid dynamics of the fluid core. Here we present the first high resolution numerical model that solves simultaneously the rigid body dynamics of the mantle and the Navier-Stokes equation for the liquid core. This method takes naturally into account dissipative processes in the fluid that are ignored in current Nutation models. We find that the Free Core Nutation (FCN) mode, mostly a toroidal fluid flow if the mantle has a large moment of inertia, enters into resonance with nearby modes if the mantle's moment of inertia is reduced. These mode interactions seem to be completely analogous to the ones discovered by Schmitt (2006) in a uniformly rotating ellipsoid with varying flattening.
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sensitivity of the free core Nutation and the chandler wobble to changes in the interior structure of mars
Physics of the Earth and Planetary Interiors, 2000Co-Authors: Tim Van Hoolst, Veronique Dehant, Pascale DefraigneAbstract:Abstract In view of the forthcoming Mars missions with seismological and geodetic experiments on board, the sensitivity of Mars' normal modes to interior structure changes is examined. The emphasis is put on the Chandler Wobble (CW) and the Free Core Nutation (FCN), as both can play an important role in the Nutations and tides of Mars. The FCN, especially, is found to have a large potential for inferring properties of the interior structure of Mars. If observed, it will prove that Mars contains a liquid core, and information about the core radius and density jump at the Core–Mantle Boundary (CMB) can be obtained. Spheroidal oscillation modes of Mars are also shown to provide a powerful and additional constraint on the Martian interior.
