Originally designed for waveform approximants, the effective precession parameter $χ_\mathrm{p}$ is the most commonly used quantity to characterize spin-precession effects in gravitational-wave observations of black-hole binary coalescences. We point out that the current definition of $χ_\mathrm{p}$ retains some, but not all, variations taking place on the precession timescale. We rectify this inconsistency and propose more general definitions that either fully consider or fully average those oscillations. Our generalized parameter $χ_\mathrm{p}\in[0,2]$ presents an exclusive region $χ_\mathrm{p}>1$ that can only be populated by binaries with two precessing spins. We apply our prescriptions to current LIGO/Virgo events and find that posterior distributions of $χ_\mathrm{p}$ tend to show longer tails at larger values. This appears to be a generic feature, implying that (i) current $χ_\mathrm{p}$ measurement errors might be underestimated, but also that (ii) evidence for spin precession in current data might be stronger than previously inferred. Among the gravitational-wave events released to date, that which shows the most striking behavior is GW190521.
One of the post-Keplerian (PK) parameters determined in timing analyses of several binary pulsars is the fractional periastron advance per orbit $k^\mathrm{PK}$. Along with other PK parameters, it is used in testing general relativity once it is translated into the periastron precession $\dotω^\mathrm{PK}$. It was recently remarked that the periastron $ω$ of PSR J0737--3039A/B may be used to measure/constrain the moment of inertia of A through the extraction of the general relativistic Lense-Thirring precession $\dotω^\mathrm{LT,\,A}\simeq -0.00060^\circ\,\mathrm{yr}^{-1}$ from the experimenta…
In the Double Pulsar, the Lense-Thirring periastron precession $\dotω^\mathrm{LT}$ should be measured by the end of this decade. The analyses recently appeared in the literature rely upon a formula for $\dotω^\mathrm{LT,\,A}$ induced by the spin angular momentum ${\boldsymbol{S}}^\mathrm{A}$ of A valid if the orbital angular momentum $\boldsymbol{L}$ and ${\boldsymbol{S}}^\mathrm{A}$ are aligned, and neglecting $\dotω^\mathrm{LT,\,B}$ because of the smallness of ${\boldsymbol{S}}^\mathrm{B}$. The impact on $\dotω^\mathrm{LT,\,A}$ of the departures of the ${\boldsymbol{S}}^\mathrm{A}$-$\boldsym…
Recently, some S-stars (S4711, S62, S4714) orbiting the supermassive black hole (SMBH) in Sgr A$^\ast$ with short orbital periods ($7.6\,\mathrm{yr}\leq P_\mathrm{b}\leq 12\,\mathrm{yr}$) were discovered. It was suggested that they may be used to measure the general relativistic Lense-Thirring (LT) precessions of their longitudes of ascending node $\mathitΩ$ induced by the SMBH's angular momentum $\boldsymbol{J}_\bullet$. In fact, the proposed numerical estimates hold only in the particular case of a perfect alignment of $\boldsymbol{J}_\bullet$ with the line of sight, which does not seem to b…
At the second post-Newtonian (2PN) order, the secular pericentre precession $\dotω^\mathrm{2PN}$ of either a full two-body system made of well detached non-rotating monopole masses of comparable size and a restricted two-body system composed of a point particle orbiting a fixed central mass have been analytically computed so far with a variety of approaches. We offer our contribution by analytically computing $\dotω^\mathrm{2PN}$ in a perturbative way with the method of variation of elliptical elements by explicitly calculating both the direct contribution due to the 2PN acceleration ${\boldsy…
We confront the predicted gyroscopic precession (in particular the geodetic precession) from metric $f(R)$ theory with the data provided by the mission, Gravity Probe--B. We find the constraint, $|a_2| < 1.33\times 10^{12} \mathrm{m}^2$, where $a_2$ is the coefficient assessing the strength of the lowest order correction to the Einstein--Hilbert action for a metric $f(R)$ theory with $f$ analytic. This constraint improves over astrophysical bounds provided by massive black holes and planetary precession which are $|a_2|\gtrsim 10^{17} \mathrm{m}^2$ and $|a_2|\lesssim 1.2\times10^{18} \mathrm{m…
Recently, it has been shown that rocky planets orbiting neutron stars can be habitable under non unrealistic circumstances. If a distant, pointlike source of visible light such as a Sun-like main sequence star or the gravitationally lensed accretion disk of a supermassive black hole is present as well, possible temporal variations $Δ\varepsilon_\mathrm{p}(t)$ of the planet's axial tilt $\varepsilon_\mathrm{p}$ to the ecliptic plane should be included in the overall habitability budget since the obliquity determines the insolation at a given latitude on a body' s surface. I point out that, for …
Rapid localization of gravitational-wave events is important for the success of the multi-messenger observations. The forthcoming improvements and constructions of gravitational-wave detectors will enable detecting and localizing compact-binary coalescence events even before mergers, which is called early warning. The performance of early warning can be improved by considering modulation of gravitational wave signal amplitude due to the Earth rotation and the precession of a binary orbital plane caused by the misaligned spins of compact objects. In this paper, for the first time we estimate lo…
We comment on a recent study reporting evidence for the general relativistic Lense-Thirring secular precession of the inclination $I$ of the orbital plane to the plane of the sky of the tight binary system PSR J1141-6545 made of a white dwarf and an emitting radiopulsar of comparable masses. The quadrupole mass moment $Q_2^\mathrm{c}$ and the angular momentum ${\boldsymbol S}^\mathrm{c}$ of the white dwarf cause the detectable effects on $I$ with respect to the present-day accuracy in the pulsar's timing. The history-dependent and model-dependent assumptions to be made on $Q_2^\mathrm{c}$ and …
Putative natural massive satellites (exomoons) has gained increasing attention, where they orbit Jupiter-like planets within the habitable zone of their host main sequence star. An exomoon is expected to move within the equatorial plane of its host planet, with its spin ${\boldsymbol S}_\mathrm{s}$ aligned with its orbital angular momentum $\boldsymbol L$ which, in turn, is parallel to the planetary spin ${\boldsymbol S}_\mathrm{p}$. If, in particular, the common tilt of such angular momenta to the satellite-planet ecliptic plane, assumed fixed, has certain values, the latitudinal irradiation …
We numerically and analytically work out the first-order post-Newtonian (1pN) orbital effects induced on the semimajor axis $a$, the eccentricity $e$, the inclination $I$, the longitude of the ascending node $Ω$, the longitude of perihelion $\varpi$, and the mean longitude at epoch $ε$ of a test particle orbiting its primary, assumed static and spherically symmetric, by a distant massive third body X. For Mercury, the rates of change of the linear trends found are $\dot I_\mathrm{1pN}^\mathrm{X} = -4.3\,\mathrm{microarcseconds\,per\,century}\,\left(μ\mathrm{as\,cty}^{-1}\right)$, $\dotΩ_\mathr…
We derive an effective potential for binary black-hole (BBH) spin precession at second post-Newtonian order. This effective potential allows us to solve the orbit-averaged spin-precession equations analytically for arbitrary mass ratios and spins. These solutions are quasiperiodic functions of time: after a fixed period the BBH spins return to their initial relative orientations and jointly precess about the total angular momentum by a fixed angle. Using these solutions, we classify BBH spin precession into three distinct morphologies between which BBHs can transition during their inspiral. We…
The Hermean average perihelion rate $\dotω^\mathrm{2PN}$, calculated to the second post-Newtonian (2PN) order with the Gauss perturbing equations and the osculating Keplerian orbital elements, ranges from $-18$ to $-4$ microarcseconds per century $\left(μ\mathrm{as\,cty}^{-1}\right)$, depending on the true anomaly at epoch $f_0$. It is the sum of four contributions: one of them is the direct consequence of the 2PN acceleration entering the equations of motion, while the other three are indirect effects of the 1PN component of the Sun's gravitational field. An evaluation of the merely formal un…
A New Window for Testing the PPN in the Strong-Field Regime: Stellar Rotation of S301
Institute for Research in Fundamental Sciences (IPM)（基础科学研究所）；Damghan University（达姆甘大学）；Khazar University（哈扎尔大学）；Università di Napoli “Federico II”（那不勒斯费德里科二世大学）；Istituto Nazionale di Fisica Nucleare (INFN), sez. di Napoli（意大利国家核物理研究所（INFN）那不勒斯分部）；Scuola Superiore Meridionale（南方高等学院）
We present calculations of gyroscope precession in spacetimes described by Levi-Civita and Lewis metrics, under different circumstances. By doing so we are able to establish a link between the parameters of the metrics and observable quantities, providing thereby a physical interpretation for those parameters, without specifying the source of the field.
Black-hole ringdown with templates capturing spin precession: A reanalysis of GW190521
Universitá degli Studi di Milano-Bicocca（米兰比可卡大学）；INFN, Sezione di Milano-Bicocca（意大利国家核物理研究所米兰比可卡分部）；Institute of Astrophysics, FORTH（基础与技术研究基金会天体物理研究所）；INFN, Sezione di Roma（意大利国家核物理研究所罗马分部）
Measurement of spin-precession in black hole binary mergers observed with gravitational waves is an exciting milestone as it relates to both general relativistic dynamics and astrophysical binary formation scenarios. In this study, we revisit the evidence for spin-precession in GW200129 and localize its origin to data in LIGO Livingston in the 20--50\,Hz frequency range where the signal amplitude is lower than expected from a non-precessing binary given all the other data. These data are subject to known data quality issues as a glitch was subtracted from the detector's strain data. The lack o…
Spin precession in merging black-hole binaries is a treasure trove for both astrophysics and fundamental physics. There are now well-established strategies to infer from gravitational-wave data whether at least one of the two black holes is precessing. In this paper we tackle the next-in-line target, namely the statistical assessment that the observed system has two precessing spins. We find that the recently developed generalization of the effective precession spin parameter $χ_\mathrm{p}$ is a well-suited estimator to this task. With this estimator, the occurrence of two precessing spins is …
In the framework of parallelism general relativity (PGR), the Dirac particle spin precession in the rotational gravitational field is studied. In terms of the equivalent tetrad of Kerr frame, we investigate the torsion axial-vector spin coupling in PGR. In the case of the weak field and slow rotation approximation, we obtain that the torsion axial-vector has the dipole-like structure, but different from the gravitomagnetic field, which indicates that the choice of the Kerr tetrad will influence on the physics interpretation of the axial-vector spin coupling.
Toward a complete understanding of the properties of GW190521
The University of Texas at Austin（德克萨斯大学奥斯汀分校）；California Institute of Technology（加州理工学院）；LIGO Laboratory（LIGO实验室）；Rochester Institute of Technology（罗切斯特理工学院）
The inclination of low-eccentricity orbits is shown to significantly affect the orbital parameters, in particular, the Keplerian, nodal precession, and periastron rotation frequencies, which are interpreted in terms of observable quantities. For the nodal precession and periastron rotation frequencies of low-eccentricity orbits in a Kerr field, we derive a Taylor expansion in terms of the Kerr parameter at arbitrary orbital inclinations to the black-hole spin axis and at arbitrary radial coordinates. The particle radius, energy, and angular momentum in the marginally stable circular orbits are…
Since the initial discovery of gravitational waves in 2015, significant developments have been made towards waveform interpretation and estimation of compact binary source parameters. We present herein an implementation of the generalized precession parameter $\langle χ_p \rangle$, which averages over all angular variations on the precession timescale, within the RIFT parameter estimation framework. Relative to the originally-proposed precession parameter $χ_p$, which characterizes the single largest dynamical spin in a binary, this new parameter $\langle χ_p \rangle$ has a unique domain $1 < …
We calculate how strongly one can put constraints on alternative theories of gravity such as Brans-Dicke and massive graviton theories with LISA. We consider inspiral gravitational waves from a compact binary composed of a neutron star (NS) and an intermediate mass black hole (IMBH) in Brans-Dicke (BD) theory and that composed of 2 super massive black holes (SMBHs) in massive graviton theories. We use the restricted 2PN waveforms including the effects of spins. We also take both precession and eccentricity of the orbit into account. For simplicity, we set the fiducial value for the spin of one…
The short gravitational wave signal from the merger of compact binaries encodes a surprising amount of information about the strong-field dynamics of merger into frequencies accessible to ground-based interferometers. In this paper we describe a previously-unknown "precession" of the peak emission direction with time, both before and after the merger, about the total angular momentum direction. We demonstrate the gravitational wave polarization encodes the orientation of this direction to the line of sight. We argue the effects of polarization can be estimated nonparametrically, directly from …
We perform a full analytical and numerical treatment, to the first post-Newtonian (1pN) order, of the general relativistic long-term spin precession of an orbiting gyroscope due to the mass quadrupole moment $J_2$ of its primary without any restriction on either the gyro's orbital configuration and the orientation in space of the symmetry axis $\boldsymbol{\hat{k}}$ of the central body. We apply our results to the past spaceborne Gravity Probe B (GP-B) mission by finding a secular rate of its spin's declination $δ$ which may be as large as $\lesssim 30-40\,\mathrm{milliarcseconds\,per\,year\,(…
Since gravitational and electromagnetic waves from a compact binary coalescence carry independent information about the source, the joint observation is important for understanding the physical mechanisms of the emissions. Rapid detection and source localization of a gravitational wave signal are crucial for the joint observation to be successful. For a signal with a high signal-to-noise ratio, it is even possible to detect it before the merger, which is called early warning. In this letter, we estimate the performances of the early warning for neutron-star black-hole binaries, considering the…
Spinformation: do gravitational-wave events carry information beyond effective spins?
LIGO Laboratory, Massachusetts Institute of Technology（LIGO实验室，麻省理工学院）；Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology（卡弗里天体物理学与空间研究所，麻省理工学院）；Department of Physics, Massachusetts Institute of Technology（麻省理工学院物理系）；Center for Computational Astrophysics, Flatiron Institute（计算天体物理学中心，西蒙斯平顿研究所）；Dipartimento di Fisica “G. Occhialini”, Universitá degli Studi di Milano-Bicocca（米兰比可卡大学“G.奥恰利尼”物理系）；INFN, Sezione di Milano-Bicocca（意大利国家核物理研究所，米兰比可卡分部）
In a previous work (arXiv:1609.05654v2), an experimental setup aiming at the measurement of deviations from the Newtonian $1/r^2$ distance dependence of gravitational interactions was proposed. The theoretical idea behind this setup was to study the trajectories of a "Satellite" with a mass $m_{\rm S} \sim {\cal O}(10^{-9})$ $\mathrm{g}$ around a "Planet" with mass $m_{\rm P} \in [10^{-7},10^{-5} ]$ $\mathrm{g}$, looking for precession of the orbit. The observation of such feature induced by gravitational interactions would be an unambiguous indication of a gravitational potential with terms d…
Recently, the possibility that several starless telluric planets may form around supermassive black holes (SMBHs) and receive an energy input from the hole's accretion disk, which, under certain plausible circumstances, may make them habitable in a terrestrial sense, has gained increasing attention. In particular, an observer on a planet orbiting at distance $r=100$ Schwarzschild radii from a maximally rotating Kerr SMBH with mass $M_\bullet = 1\times 10^8\,M_\odot$ in a plane slightly outside the equator of the latter, would see the gravitationally lensed accretion disk the same size as the S…
The macroscopic precession model of quasi-periodic oscillations for rotating compact objects
Università di Camerino（卡梅里诺大学）；University at Albany SUNY（奥尔巴尼州立纽约大学）；INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所-布雷拉天文台）；Al-Farabi Kazakh National University（阿尔法拉比哈萨克国立大学）；INAF - Catania Astrophysical Observatory（意大利国家天体物理研究所-卡塔尼亚天体物理观测站）；ICRANet（国际相对论天体物理中心网络）
