arXiv subjects

Hong-Bo Jin

Publications and source records attributed to Hong-Bo Jin.

At least 19 recordsLinked to original sources

arXiv2026

Eight Local Couplings of Gravitational Waves from Unified Field Equations

A gravitational-wave (GW) detector records a linear mixture of local couplings under the assumption that extra polarizations enter geodesic deviation. Vacuum general relativity (GR) admits two transverse-traceless (TT) amplitudes. It remains to determine the largest set of couplings that can sit in that mixture, and whether a tensor-only arm-length result selects GR uniquely. The little group $E(2)$ of a null four-momentum classifies the strain amplitudes $\mathbf{p}=(p_{+},p_{\times},p_{x},p_{y},p_{b},p_{\ell})$, commonly written $h_{P}$, which determine the electric tidal tensor along a ray. Geodesic deviation, recorded as differential arm length, therefore contains only those $p_{P}$ that enter that tensor. Lorentz mixing at helicity $\pm1$ supplies a gravito-magnetic (GEM) field that does not enter the tidal tensor. if GEM field is static, that does not propagate as a wave. A time-varying helicity-$\pm1$ current sources a GEM wave that enters the mixture as a coupling, to be isolated by its measured quantity. For a radiation-zone wave that depends only on retarded time, $\betag_{\perp}=\hat{\mathbf{k}}\times\partial_{t}(p_{x},p_{y})$, and the eight couplings are $\Pvec=(\mathbf{p},\betag_{\perp})$. Here we adopt unified field equations on $\mathbf{p}$ to clarify the origin of each component of $\Pvec$; the measured quantity of each coupling then isolates the polarizations in that mixture, which favors identification of distinct polarizations and model tests.

gr-qc↗

arXiv2026

Directional Response Optimization through Linear Recombination of Time-Delay Interferometry Channels in Space-based Gravitational Wave Detection

Space-based gravitational-wave detectors such as LISA, Taiji, and TianQin employ time-delay interferometry (TDI) to cancel laser-frequency noise for unequal-arm constellations. Since different TDI observables exhibit distinct sky responses, a linear combination of candidate channels can enhance the average response over one sky region while suppressing that of another. We construct a frequency-domain response matrix for TDI combinations, average it across target and suppressed sky regions, and derive the optimal weights via a generalized eigenvalue problem that maximizes the ratio between these two regional responses. At millihertz frequencies, examples with the $A$, $E$, and $T$ channels, the Sagnac combinations $\alpha$, $\beta$, and $\gamma$, and 16-links TDI show that a sky-region null and a large regional contrast are possible near the chosen frequency, with eigenvalues $\rho$ ranging from $\mathcal{O}(10)$ for small bases to $\mathcal{O}(10^2)$ for the larger set. The method is therefore expected to be well suited to nearly monochromatic sources such as the resolved Galactic double white dwarf binaries in the millihertz band. The Target-to-Suppression Ratio (TSR) peaks near the design frequency and falls quickly away from it, so the optimized weight vector is inherently narrowband and suited to targeted searches around a chosen frequency and sky direction.

gr-qc↗

arXiv2026

O5 dark-siren forecasts for modified GW propagation: background robustness of the $\Xi$ posterior

Binary black hole mergers without electromagnetic counterparts are expected to dominate O5 gravitational-wave catalogs. Recent CHIMERA~2.0 forecasts typically fix $\Omega_m$ to a CMB-informed value and use spectroscopic hosts when available, but the corresponding sensitivity of the $\Xi$ posterior has not been assessed for pure dark sirens on the public O5 mock catalog. We analyze 300 O5-sensitivity mock events without galaxy catalogs, varying $\Omega_m$ over $[0.20,\,0.35]$ (including Planck $0.315$), and compare fixed-background inference with joint $(H_0,\,\Omega_m,\,\Xi)$ inference. The marginalized $\Xi$ posterior is $0.9783 \pm 0.3548$ and shows no change across this interval. Only GW luminosity distances enter the analysis, so the likelihood constrains $\Xi\, D_L^{\rm EM}(H_0,\,\Omega_m)$; when $\Omega_m$ is changed, $H_0$ shifts to compensate and the $\Xi$ marginal remains unchanged. Joint inference gives $\Xi^{\rm joint} = 0.9550 \pm 0.3710$, with $|\rho| \lesssim 0.05$ for the $\Omega_m$--$\Xi$ and $H_0$--$\Xi$ pairs, whereas $\rho_{H_0 \Omega_m} \simeq -0.4$ and the $H_0$ median moves by $\simeq 4.2\,{\rm km\,s^{-1}\,Mpc^{-1}}$ over the adopted $\Omega_m$ range. Galaxy-catalog analyses on the same events at fixed $\Omega_m = 0.3$ reach $\sim 7.5\%$ precision on $\Xi$, compared with $\pm 36.3\%$ here; the larger uncertainty is driven mainly by missing host redshifts. Sub-percent $\Xi$ tests will therefore still require measured redshifts even if dark sirens dominate the detection rate.

astro-ph.CO↗

arXiv2026

Solving Hamiltonian Constraint Equation with Physics-Informed Neural Networks

Numerical relativity (NR), solving Einstein equation numerically, plays an important role in source modelling for gravitational wave astronomy. Traditional methods for NR including finite difference method, spectral method and finite element method have been well developed. But newly developed neural network methods for partial differential equations (PDE) have not been well studied yet for NR. We present a Physics-Informed Neural Network (PINN) method to solve the Hamiltonian constraint equation for binary black hole (BBH) initial data in NR. This equation is a highly non-linear elliptic PDE, posing significant challenges for conventional PINN approaches. To overcome these difficulties, we introduce a set of new techniques. We show that our PINN together with these techniques can successfully solve the Hamiltonian constraint equation for generic BBH systems. Validation against the traditional results demonstrates the high accuracy and robustness of our method, revealing the immense potential of constructing a PINN-based initial data solution to all BBH systems for NR.

gr-qc↗

arXiv2026

Relativistic Time Scales and Transformations in the Solar System

Each solar-system observable is characterised by celestial reference system (CRS) coordinate time, proper time on its world line, and the transformation between them. Ephemerides and Deep Space Network (DSN) tracking use the International Astronomical Union (IAU) barycentric and body-centric hierarchy, now extended to cislunar and Mars work. The IERS Conventions, Moyer radiometric models, and recent lunar-time papers distribute metric, scale, and tracking formulae across separate manuals. Merged Chang'e- or Tianwen-class data can acquire microsecond-level range and Doppler biases unless proper time $\tau$ is mapped consistently to barycentric and body-centric coordinate times. We present a unified 1PN documentation chain: tabulated harmonic Christoffel symbols through $\mathcal{O}(c^{-4})$, the barycentric-geocentric-terrestrial coordinate-time sequence, Fermi normal coordinates, null-geodesic observables, and a 1PN two-way range-rate expansion, applied in parallel to Mars (MCRS/MCG) and lunar (LCRS/TCL) body-centric systems. The chain yields a Mars areoid-geoid metric clock-rate difference of $\sim$48~$\mu$s\,day$^{-1}$ and lunar selenoid-geoid rates of $\sim$57.4-58.7~$\mu$s\,day$^{-1}$ consistent with published nested coefficients. Mars-range Shapiro-rate terms reach $10^{-12}$-$10^{-13}$. Multi-CRS consistency relies on documented transformation chains rather than a single master clock.

astro-ph.EP↗

arXiv2026

BBN constraints on primordial black holes with a continuous memory-burden crossover

Light primordial black holes (PBHs) are disfavored as dark matter if they evaporate through standard Hawking radiation alone. The memory-burden effect can extend their lifetimes by suppressing emission after roughly half the mass is lost. Existing cosmological studies often model the onset of this phase as an instantaneous transition between semi-classical and burden-dominated evaporation. We instead treat the crossover as continuous and compare additive versus multiplicative combinations of the two rates, using a smoothed tanh profile with parameters $(q,\delta)$. Monochromatic PBHs are mapped to a decaying scalar field and evolved with Modified AlterBBN during Big Bang nucleosynthesis (BBN). The two prescriptions yield distinct exclusion curves: the additive crossover always gives weaker bounds than the multiplicative one, while both are tighter than the instantaneous transition. For $10^{5}\,\mathrm{g}\lesssim M_i\lesssim 10^{10}\,\mathrm{g}$, the additive case can permit $f_{\mathrm{PBH},0}\sim 10^{-1}$ where the multiplicative case gives $f_{\mathrm{PBH},0}\lesssim 10^{-2}$. Specifying the rate-combination rule is therefore essential when translating memory-burden models into BBN constraints on PBH dark matter.

astro-ph.CO↗

arXiv2026

Finite-Window Centered Organization of Neighboring Poles

Near-degenerate resonance poles arise widely in open-wave systems. For gravitational-wave ringdowns, inference is performed on finite time windows where neighboring quasinormal modes can be spectrally close; the waveform is then dominated by a common carrier with a slowly varying interference envelope, while representing the signal as a sum of two independently resolved damped exponentials $e^{-\ii\omega_\pm t}$ becomes numerically ill-conditioned when the dimensionless splitting $\eta=|\sigma|T_{\mathrm{eff}}$ is small. We give a finite-window organizing principle for such neighboring-pole sectors: the local two-pole singular block of the Green-function integrand is rewritten exactly about a shared carrier $\omega_c$ and half-splitting $\sigma$, and for $|\sigma t|\ll 1$ the time-domain projection is systematically a carrier plus a first-jet piece $\propto t\,e^{-\ii\omega_c t}$, without requiring a literal double pole or exceptional-point merger in parameter space. The centered first-jet basis has $O(1)$ Gram conditioning, whereas the resolved-mode basis satisfies $\mathrm{cond}(G_{\mathrm{res}})\sim 12\,\eta^{-2}$ as $\eta\to 0$ (transparent real-splitting slice). We supply finite-window diagnostics in which $\kappa$ marks when the jet correction must be retained and $\eta^2$ sets the residual error scale once it is retained. Minimal two-pole numerics verify the scaling. For Kerr black holes we fix one adjacent-overtone mode pair (catalog label \texttt{pair45}; shared $(l,m)$ and consecutive overtones in our indexed tabulation), scan spin $a\in[0.8770,0.8810]$, and adopt the spectral window proxy $T_{\mathrm{spec}}=\beta/|\Im\omega_c|$ with $\beta=2.0$ to illustrate the same conditioning contrast in a near-degenerate sector.

gr-qc↗

arXiv2026

Pair-Dependent Drift of Kerr Neighboring-Overtone Gap Minima

We study adjacent Kerr quasinormal-mode overtones under a spin scan with overtone labels held fixed, using a public Leaver-type solver on a uniform grid. The observable is the modulus of the complex-frequency separation between neighbors; its minima are analyzed through the spin derivative of the squared separation, which supplies a smooth real diagnostic without differentiating the modulus itself. Clear interior minima appear, but their spin locations shift between neighboring pairs even within one $(s,\ell,m)$ sector and align with dominant zeros of the diagnostic and with radial turning of the separation vector in the complex-frequency plane. Representative extra sectors and smooth no-trigger cases support selectivity. Minimum drift is naturally read as drift of that dominant zero; the language connects to complex-spectral pole proximity for Kerr flows without identifying each minimum with an exceptional-point coalescence or claiming a universal rule over the full spectrum.

gr-qc↗

arXiv2025

Lunar and Terrestrial Time Transformation Based on the Principle of General Relativity

Lunar time metrology necessitates a unified temporal framework beyond Earth, requiring an independent lunar system for timekeeping, dissemination, and calendrics. Recent American publications define Lunar Coordinate Time (LTC) within relativity and propose a Terrestrial Time (TT) to LTC conversion formula. However, this formula's derivation and assumptions are contested. The complex dynamics within the solar system can be simplified by decomposing relationships into hierarchical wide-area (external problem) and local-area (internal problem) levels. Grounded in the symmetry and conservation laws of physics, Einstein's general relativity emphasizes two key principles: (i) Equal weighting: Relationships among multi-level coordinate systems are independent and self-similar (analogous to fractals). (ii) *Locality*: The laws of physics retain invariant forms only in local coordinate systems. Specifically, a non-rotating system corresponds to the Frenet frame along a particle's geodesic. Preserving physical law invariance requires restricting rotating references strictly to the local domain; defining the orientation of an Earth-centered system using distant celestial bodies violates general relativity's locality principle. This work derives the relationship between coordinate time and proper time. Using the Earth-Moon system as an intermediary, it obtains a simplified transformation formula between LTC and TT. An independent and universal lunar standard time framework is proposed. Crucially, the derived coordinate time transformation coefficient exhibits long-term secular variation. This variation can be measured and predicted through precise Earth-Moon time comparisons.

gr-qc↗

arXiv2025

New Physics Search at the CEPC: a General Perspective

The Circular Electron-Positron Collider (CEPC), a proposed next-generation Higgs factory, provides new opportunities to explore physics beyond the Standard Model (SM). With its clean electron-positron collision environment and the ability to collect large samples of Higgs, W, and Z bosons, the CEPC enables precision measurements and searches for new physics. This white paper outlines the CEPC's discovery potential, including studies of exotic decays of the Higgs, Z, and top quarks, dark matter and dark sector phenomena, long-lived particles, supersymmetry, and neutrino-related signatures. Advanced detector technologies and reconstruction techniques, such as one-to-one correspondence reconstruction and jet origin identification, significantly improve sensitivity to rare and weakly interacting processes. The CEPC is particularly well suited to probe the electroweak phase transition and test models of electroweak baryogenesis and dark sector interactions. In addition, global fit analyses highlight the CEPC's complementary role in constraining a wide range of new physics scenarios. These features position the CEPC as a powerful tool for exploring the next frontier in fundamental particle physics in the post-Higgs discovery era.

hep-ex↗

arXiv2025

Parameter extraction of the stochastic gravitational wave background with peak-like templates in millihertz

We investigate a framework for extracting parameters of stochastic gravitational wave background (SGWB) with peak-like templates in the millihertz frequency band, and analyzing transient contamination effects on parameter reconstruction. We present the spectrum and spectrogram under different conditions and provide the results of parameter reconstruction. Using templates from the early universe, we demonstrate that the peak-like templates outperform the broken power law (BPL) templates in power-law exponents recovery and peak frequency localization. The reconstruction results obtained using data from Fast Fourier Transform (FFT) are better than those obtained using data from Short-Time Fourier Transform (STFT) which is based on the spectrogram. For the single-peak template, the estimation accuracy of the exponent and peak frequency surpasses that of the BPL template by an order of magnitude, but demonstrates less precision in amplitude estimation compared to BPL. Regarding the double-peak template, parameter estimation results derived from the FFT methodology consistently outperform those obtained using STFT. Nevertheless, transient signals exhibit a detrimental impact on parameter estimation precision, causing errors to increase by an order of magnitude, particularly in multi-peak scenarios. This framework provides an example for using templates to analyze data from space-based gravitational wave detectors.

gr-qc↗

arXiv2025

Probing Gravitational Quantum Field Theory through Polarization Fingerprints of Gravitational Waves

Gravitational Quantum Field Theory (GQFT) has been proposed as a candidate framework to reconcile general relativity with quantum field theory, and a distinctive imprint on gravitational-wave (GW) polarizations is crucially predicted. While general relativity allows only two tensor modes ($+, \times$), GQFT additionally favors a massless breathing scalar mode, providing a compelling yet largely unexplored observational target for testing quantum gravity. The central challenge is therefore to assess, in a mission-agnostic manner, how well future space-based interferometers can disentangle and detect these tensor and scalar polarization components across the sky. In this work, we develop a model-independent response formalism for LISA- and Taiji-like detectors by incorporating first-order orbital dynamics in the Solar System Barycenter frame. This framework yields three key observational consequences: (1) characteristic interference patterns between tensor and scalar modes, (2) a generalized, model-independent response function for the breathing mode, and (3) sky-position-dependent strategies that optimize detectability. We further translate the formalism into comprehensive polarization maps that provide complete sky coverage and remain fully compatible with existing mission designs, thereby circumventing the need for challenging direct breathing-mode measurements. Overall, our results deliver practical tools for future data analysis and establish a systematic avenue to test fundamental theories of gravity through their GW polarization fingerprints.

gr-qc↗

arXiv2025

Detecting stochastic gravitational wave background from cosmic strings with next-generation detector networks: Component separation based on a multi-source astrophysical foreground noise model

Detecting stochastic gravitational wave background (SGWB) from cosmic strings is crucial for unveiling the evolutionary laws of the early universe and validating non-standard cosmological models. This study presents the first systematic evaluation of the detection capabilities of next-generation ground-based gravitational wave detector networks for cosmic strings. By constructing a hybrid signal model incorporating multi-source astrophysical foreground noise, including compact binary coalescences (CBCs) and compact binary hyperbolic encounters (CBHEs), we propose an innovative parameter estimation methodology based on multi-component signal separation. Numerical simulations using one-year observational data reveal three key findings: (1) The CE4020ET network, comprising the Einstein Telescope (ET-10 km) and the Cosmic Explorer (CE-40 km and CE-20 km), achieves nearly one order of magnitude improvement in constraining the cosmic string tension $G\mu$ compared to individual detectors, reaching a relative uncertainty $\Delta G\mu / G\mu < 0.5$ for $G\mu > 3.5 \times 10^{-15}$ under standard cosmological framework; (2) The network demonstrates enhanced parameter resolution in non-standard cosmological scenarios, providing a novel approach to probe pre-Big Bang Nucleosynthesis cosmic evolution; (3) Enhanced detector sensitivity amplifies CBHE foreground interference in parameter estimation, while precise modeling of such signals could further refine $G\mu$ constraints by $1-2$ orders of magnitude. This research not only quantifies the detection potential of third-generation detector networks for cosmic string models but also elucidates the intrinsic connection between foreground modeling precision and cosmological parameter estimation accuracy, offering theoretical foundations for optimizing scientific objectives of next-generation gravitational wave observatories.

astro-ph.CO↗

arXiv2024

Beam quality $M^2(\psi)$ factor, spot rotation angle, and angular speed in general laser beams

A unified definition for the rotation angle and rotation angular speed of general beams, including those with orbital angular momentum (OAM), has been lacking until now. The rotation of a general beam is characterized by observing the rotational behavior of the directions of the extreme spot sizes during propagation. We introduce the beam quality $M^2(\psi)$ factor to characterize the unique beam quality of a general beam across all directions, not limited to the $x$- or $y$-axes. Besides that, we present the beam center $s_{\psi}(\psi,z)$, spot size $w_{\psi}(\psi,z)$, waist position, waist radius, and divergence angle along the direction that forms an angle $\psi$ with the $x$-axis in the plane perpendicular to the $z$-axis for the general beam. Furthermore, this paper presents rapid calculation formulas for these parameters, utilizing the mode expansion method (MEM). Subsequently, we prove that only two extreme spot sizes exist in a given detection plane and the angle between the maximum and minimum spot angles is consistently $90^{\circ}$ during the propagation. We also prove the spot rotation angles converge as $z$ approaches either positive or negative infinity. We first show the extreme spot sizes, spot rotation angle, and angular speed for the vortex beam. Our formulas efficiently differentiate between vortex OAM beams and asymmetry OAM beams.

physics.optics↗

arXiv2024

Approximate model for the coupling of far-field wavefront errors and jitter in space-based gravitational wave laser interferometry

Space-based gravitational wave observatories, such as LISA, Taiji, and TianQin, employ long-baseline laser interferometry, necessitating displacement measurement sensitivity at 1 pm/$\sqrt{Hz}$ level. A significant challenge in achieving this precision is the coupling noise arising from far-field wavefront errors (WFE) and laser pointing jitter. This paper presents a comprehensive noise model that incorporates three critical factors: transmitted WFE, static pointing angle, and laser beam jitter. Utilizing the Nijboer-Zernike diffraction theory, we derive an approximate expression for far-field WFE, ensuring minimal error and efficient computational performance. The approximate expression has convincing physical interpretability and reveals how various Zernike aberrations and their coupling impact far-field WFE. Furthermore, the study identifies that correcting optical axis deviations induced by $Z_3^{\pm1}$ through beam tilt exacerbates far-field WFE, underscoring the necessity for active suppression of $Z_3^{\pm1}$. The proposed model facilitates detailed system simulations of the laser link, evaluates Tilt-to-Length (TTL) noise, and offers theoretical insights for system optimization.

astro-ph.IM↗

arXiv2024

Intermediate-mass-ratio inspirals with general dynamical friction in dark matter minispikes

The intermediate-mass-ratio inspirals (IMRIs) may be surrounded by dark matter (DM) minispikes. The dynamical friction from these DM minispike structures can affect the dynamics and the gravitational wave (GW) emission of the IMRIs. We analyze the effects of general dynamical friction, with a particular contribution from DM particles moving faster than the stellar-mass black hole in an eccentric IMRI. Our calculation show that these DM particles tends to eccentricify the orbit, therefore the evolution of the eccentricity depends on the competition between the fast moving DM particles and the slow moving DM particles. The results show that the dynamical friction enhances the eccentricity when $\gamma_\mathrm{sp}\lesssim2.0$, and the general dynamical friction is able to increase the eccentricity. We also analyze the effects of general dynamical friction on the GW characteristic strain. The results indicate that the characteristic strain is suppressed at lower frequencies, and the peak value of the characteristic strain occurs at higher frequencies as the power law index of DM minispike $\gamma_\mathrm{sp}$ increases. For the first time, a relation between the frequency peak value of characteristic strain of GWs and $\gamma_\mathrm{sp}$ is established. Using this analytical relation, the presence of DM and its halo density may be determined potentially from future GW data.

astro-ph.HE↗

arXiv2024

Gravitational Wave Polarization Detection with Tetrahedron Constellation of Gravitational Wave Observatory

For the first time, we have introduced the Tetrahedron Constellation of Gravitational Wave Observatory (TEGO) composed of four identical spacecrafts (S/Cs). The laser telescopes and their pointing structures are mounted on the S/C platform and are evenly distributed at three locations 120 degrees apart. These structures form automatically a stable mass center for the platform. The time delay interferometry (TDI) are used to suppress the frequency noise of Gravitational Wave (GW) detector. The unequal arm Michelson TDI configuration and the Sagnac TDI configuration are equally effective at eliminating the laser frequency noise based on the TEGO configuration. Furthermore, comparing to the configurations of LISA, Taiji, and TianQin, the TEGO has more combinations of optical paths in its TDI system sensitive to GW signals. The six arms of TEGO are simultaneously sensitive to the six polarization modes of GWs. The sensitivity implies that GW modes beyond the predictions of general relativity (GR) can be detected directly. For instance, a scalar longitudinal mode of GWs, which is not predicted by GR, has been identified as a dominant polarization component. This mode is found to be evident in the response amplitudes of the TEGO arms, such as between S/C1 and S/C4, and S/C3 and S/C4, at certain orbital positions.

gr-qc↗

arXiv2024

Sky location of Massive Black Hole Binaries in the foreground of Galactic white dwarf binaries

For space-based gravitational wave (GW) detection, the main noise source for massive black hole binaries (MBHBs) is attributed to approximately $10^7$ double white dwarf binaries in the foreground. For a GW source, the amplitude of the detector response, recorded by a space-based gravitational wave detector, exhibits a modulation effect with a year period when observing the source from various orbital positions. Under the adverse conditions mentioned above, where there is a strong foreground noise and annual modulation in the signals, we employed the wavelet transform and the strong-amplitude relevant orbital position search methods, which allows the weak MBHB sources to achieve higher locating accuracy. In detail, for two MBHB sources of lower intensity, the precision of luminosity distance, represented by the ratio $\Delta D_L / D_L$ at the 95$\%$ confidence level, is enhanced by factors of $\sim$ 2. And the angular resolutions, denoted by $\Delta \Omega_s$, are enhanced by a factor of $\sim$ 20. These improvements increase the number of detectable GW sources, facilitates multi-messenger follow-up observations and provides constraints on the cosmological constant.

astro-ph.HE↗