arXiv subjects

Jin-Liang Jiang

Publications and source records attributed to Jin-Liang Jiang.

At least 19 recordsLinked to original sources

arXiv2026

The initial spin matters: the impact of rapid rotation on magnetic-field amplification at merger

A couple of milliseconds after the merger of a binary system of neutron stars can play a fundamental role in amplifying the comparatively low initial magnetic fields into magnetar strengths. The basic mechanism responsible for this amplification is the Kelvin-Helmholtz instability (KHI) and we here report the first systematic study of the impact of rapid rotation on the KHI-amplification process exploiting general-relativistic magnetohydrodynamic simulations at very high-resolutions of $35\,{\rm m}$. Concentrating on four different spinning configurations, we find that aligned, anti-aligned, and mixed (aligned/anti-aligned) spin configurations lead to markedly different growth rates of the electromagnetic (EM) energy, field topologies, and vortex properties when compared to the irrotational case. These differences arise from intrinsic variations in the system dynamics, such as tidal deformation, collision strength, and contact surface area, with the anti-aligned configuration producing the largest vorticity and growth in EM energy. Importantly, while different spin configurations lead to significantly different initial growth rates of the poloidal/toroidal components, all systems converge to a specific topological partition. Our simulations are confined to a short window in time, but the different EM energies produced as a result of spin will imprint the EM emission at merger and provide information on the spinning state at merger.

astro-ph.HE↗

arXiv2025

Long-term impact of the magnetic-field strength on the evolution and electromagnetic emission by neutron-star merger remnants

Numerical simulations are essential to understand the complex physics accompanying the merger of binary systems of neutron stars. However, these simulations become computationally challenging when they have to model the merger remnants on timescales over which secular phenomena, such as the launching of magnetically driven outflows, develop. To tackle these challenges, we have recently developed a hybrid approach that combines, via a hand-off transition, a fully general-relativistic code (FIL) with a more efficient code making use of the conformally flat approximation (BHAC+). We here report important additional developments of BHAC+ consisting of the inclusion of gravitational-wave radiation-reaction contributions and of higher-order formulations of the equations of general-relativistic magnetohydrodynamics. Both improvements have allowed us to explore BNS merger remnants with high accuracy and over timescales that would have been computationally prohibitive otherwise. More specifically, we have investigated the impact of the magnetic-field strength on the long-term (i.e., $\sim 200\,{\rm ms}$) and high-resolution (i.e., $150\,{\rm m}$) evolutions of the "magnetar" resulting from the merger of two neutron stars with a realistic equation of state. In this way, and for sufficiently large magnetic fields, we observe the weakening or suppression of differential rotation and the generation of magnetic flares in the outer layers of the remnant. These flares, driven mostly by the Parker instability, are responsible for intense and collimated Poynting flux outbursts and mass ejections. This novel phenomenology offers the possibility of seeking corresponding signatures from the observations of short gamma-ray bursts and hence revealing the existence of a long-lived strongly magnetized remnant.

astro-ph.HE↗

arXiv2024

A hybrid approach to long-term binary neutron-star simulations

One of the main challenges in the numerical modeling of binary neutron-star (BNS) mergers is long-term simulations of the post-merger remnant over timescales of the order of seconds. When this modeling includes all the aspects of complex physics, the computational costs can easily become enormous. To address this challenge in part, we have developed a novel hybrid approach in which the solution from a general-relativistic magnetohydrodynamics (GRMHD) code solving the full set of the Einstein equations in Cartesian coordinates is coupled with another GRMHD code in which the Einstein equations are solved under the Conformally Flat Condition (CFC). The latter approximation has a long history and has been shown to provide an accurate description of compact objects in non-vacuum spacetimes. An important aspect of the CFC is that the elliptic equations need to be solved only for a fraction of the steps needed for the underlying HD/MHD evolution, thus allowing for a gain in computational efficiency that can be up to a factor of $\sim 6~(230)$ in three-dimensional (two-dimensional) simulations. We present the basic features of the new code, the strategies necessary to interface it when importing both two- and three-dimensional data, and a novel and robust approach to the recovery of the primitive variables. To validate our new framework, we have carried out code tests with various coordinate systems and different numbers of spatial dimensions, involving a variety of astrophysical scenarios, including the evolution of the post-merger remnant of a BNS merger over a timescale of one second. \texttt{BHAC+}, can accurately reproduce the evolution of compact objects in non-vacuum spacetimes and that, when compared with the evolution in full general relativity, the CFC reproduces accurately both the gravitational fields and the matter variables at a fraction of the computational costs.

gr-qc↗

arXiv2024

Bulk properties of PSR J0030+0451 inferred with the compactness measurement of NICER

In 2019, Neutron star Interior Composition ExploreR (NICER) mission released its findings on the mass and radius of the isolated neutron star (INS) PSR J0030+0451, revealing a mass of approximately 1.4 solar masses ($M_{\odot}$) and a radius near 13 kilometers. However, the recent re-analysis by the NICER collaboration \citep{vinciguerra2024updated} suggests that the available data primarily yields a precise inference of the compactness for this source while the resulting mass and radius are strongly model-dependent and diverse (the 68.3\% credible regions just overlap slightly for the ST+PDT and PDT-U models). By integrating this compactness data with the equation of state (EoS) refined by our latest investigations, we have deduced the mass and radius for PSR J0030+0451, delivering estimates of $M=1.48^{+0.09}_{-0.10}~M_\odot$ and $R=12.38_{-0.70}^{+0.51}~{\rm km}$ for the compactness found in ST+PDT model, alongside $M=1.47^{+0.14}_{-0.20}~M_\odot$ and $R=12.37_{-0.69}^{+0.50}~{\rm km}$ for the compactness in PDT-U model. These two groups of results are well consistent with each other and the direct X-ray data inference within the ST+PDT model seems to be favored. Additionally, we have calculated the tidal deformability, moment of inertia, and gravitational binding energy for this NS. Furthermore, employing these refined EoS models, we have updated mass-radius estimates for three INSs with established gravitational redshifts.

astro-ph.HE↗

arXiv2024

Maximum gravitational mass $M_{\rm TOV}=2.25^{+0.08}_{-0.07}M_\odot$ inferred at about $3\%$ precision with multimessenger data of neutron stars

The maximal gravitational mass of nonrotating neutron stars ($M_{\rm TOV}$) is one of the key parameters of compact objects and only loose bounds can be set based on the first principle. With reliable measurements of the masses and/or radii of the neutron stars, $M_{\rm TOV}$ can be robustly inferred from either the mass distribution of these objects or the reconstruction of the equation of state (EoS) of the very dense matter. For the first time we take the advantages of both two approaches to have a precise inference of $M_{\rm TOV}=2.25^{+0.08}_{-0.07}~M_\odot$ (68.3\% credibility), with the updated neutron star mass measurement sample, the mass-tidal deformability data of GW170817, the mass-radius data of PSR J0030+0451 and PSR J0740+6620, as well as the theoretical information from the chiral effective theory ($χ$EFT) and perturbative quantum chromodynamics (pQCD) at low and very high energy densities, respectively. This narrow credible range is benefited from the suppression of the high $M_{\rm TOV}$ by the pQCD constraint and the exclusion of the low $M_{\rm TOV}$ by the mass function. Three different EoS reconstruction methods are adopted separately, and the resulting $M_{\rm TOV}$ and $R_{\rm TOV}$ are found to be almost identical, where $R_{\rm TOV}=11.90^{+0.63}_{-0.60}$ km is the radius of the most massive non-rotating NS. This precisely evaluated $M_{\rm TOV}$ suggests that the EoS of neutron star matter is just moderately stiff and the $\sim 2.5-3M_\odot$ compact objects detected by the second generation gravitational wave detectors are most likely the lightest black holes.

astro-ph.HE↗

arXiv2022

Bayesian analysis of neutron-star properties with parameterized equations of state: the role of the likelihood functions

We have investigated the systematic differences introduced when performing a Bayesian-inference analysis of the equation of state of neutron stars employing either variable- or constant-likelihood functions. The former have the advantage that it retains the full information on the distributions of the measurements, making an exhaustive usage of the data. The latter, on the other hand, have the advantage of a much simpler implementation and reduced computational costs. In both approaches, the EOSs have identical priors and have been built using the sound-speed parameterization method so as to satisfy the constraints from X-ray and gravitational-waves observations, as well as those from Chiral Effective Theory and perturbative QCD. In all cases, the two approaches lead to very similar results and the $90\%$-confidence levels are essentially overlapping. Some differences do appear, but in regions where the probability density is extremely small and are mostly due to the sharp cutoff set on the binary tidal deformability $\tilde Λ\leq 720$ employed in the constant-likelihood analysis. Our analysis has also produced two additional results. First, a clear inverse correlation between the normalized central number density of a maximally massive star, $n_{\rm c, TOV}/n_s$, and the radius of a maximally massive star, $R_{\rm TOV}$. Second, and most importantly, it has confirmed the relation between the chirp mass $\mathcal{M}_{\rm chirp}$ and the binary tidal deformability $\tildeΛ$. The importance of this result is that it relates a quantity that is measured very accurately, $\mathcal{M}_{\rm chirp}$, with a quantity that contains important information on the micro-physics, $\tildeΛ$. Hence, once $\mathcal{M}_{\rm chirp}$ is measured in future detections, our relation has the potential of setting tight constraints on $\tildeΛ$.

gr-qc↗

arXiv2021

Constraints on the phase transition and nuclear symmetry parameters from PSR $\mathrm{J}0740+6620$ and multimessenger data of other neutron stars

Recently, the radius of neutron star (NS) PSR J0740+6620 was measured by Neutron Star Interior Composition Explorer (NICER) and an updated measurement of neutron skin thickness of ${}^{208}$Pb ($R_{\rm skin}^{208}$) was reported by the PREX-II experiment. These new measurements can help us better understand the unknown equation of state (EOS) of dense matter. In this work, we adopt a hybrid parameterization method, which incorporates the nuclear empirical parameterization and some widely used phenomenological parameterizations, to analyze the results of nuclear experiments and astrophysical observations. With the joint Bayesian analysis of GW170817, PSR J0030+0451, and PSR J0740+6620, the parameters that characterize the ultradense matter EOS are constrained. We find that the slope parameter $L$ is approximately constrained to $70_{-18}^{+21}$ MeV, which predicts $R_{\rm skin}^{208}=0.204^{+0.030}_{-0.026}\,{\rm fm}$ by using the universal relation between $R_{\rm skin}^{208}$ and $L$. The bulk properties of canonical $1.4\,M_\odot$ NS (e.g., $R_{1.4}$ and $Λ_{1.4}$) as well as the pressure ($P_{2ρ_{\rm sat}}$) at two times the nuclear saturation density are well constrained by the data; i.e., $R_{1.4}$, $Λ_{1.4}$, and $P_{2ρ_{\rm sat}}$ are approximately constrained to $12.3\pm0.7$ km, $330_{-100}^{+140}$, and $4.1_{-1.2}^{+1.5}\times10^{34}\,{\rm dyn\,cm^{-2}}$, respectively. Besides, we find that the Bayes evidences of the hybrid star and normal NS assumptions are comparable, which indicates that current observation data are compatible with quarkyonic matter existing in the core of massive star. Finally, in the case of normal NS assumption, we obtain a constraint for the maximum mass of nonrotating NS $M_{\rm TOV}=2.30^{+0.30}_{-0.18}$ $M_\odot$. All of the uncertainties reported above are for 68.3% credible levels.

nucl-th↗

arXiv2021

Constrains on the electric charges of the binary black holes with GWTC-1 events

Testing black hole's charged property is a fascinating topic in modified gravity and black hole astrophysics. In the first Gravitational-Wave Transient Catalog (GWTC-1), ten binary black hole merger events have been formally reported, and these gravitational wave signals have significantly enhanced our understanding of the black hole. In this paper, we try to constrain the amount of electric charge with the parameterized post-Einsteinian framework by treating the electric charge as a small perturbation in a Bayesian way. We find that the current limits in our work are consistent with the result of Fisher information matrix method in previous works. We also develop a waveform model considering a leading order charge effect for binary black hole inspiral.

gr-qc↗

arXiv2021

Bayesian inference of quark star equation of state using the NICER PSR J0030+0451 data

We constrain the equation of state of quark stars within the Bayesian statistical approach using the mass and radius measurements of PSR J0030+0451 from NICER. Three types of bag models, with and without non-zero finite quark mass and/or superfluidity, are employed for quark stars made up with self-bound strange quark matter. We find the $90\%$ posterior credible boundary around the most probable values of the quark star maximum mass is $M_{\rm TOV}=2.38_{-0.23}^{+0.26}\,M_{\odot}$, within the model flexibility of the finite quark mass, the quark pairing gap, and the perturbative contribution from the one-gluon exchange. The radius of a canonical $1.4\,M_{\odot}$ quark star is $R_{\rm 1.4}\sim12.3\,{\rm km}$, smaller than the results based on neutron star models.

astro-ph.HE↗

arXiv2021

Bayesian inference of strange star equation of state using the GW170817 and GW190425 data

The observations of compact star inspirals from LIGO/Virgo provide a valuable tool to study the highly uncertain equation of state (EOS) of dense matter at the densities in which the compact stars reside. It is not clear whether the merging stars are neutron stars or quark stars containing self-bound quark matter. In this work, we explore the allowed bag-model-like EOSs by assuming the merging stars are strange quark stars (SQSs) from a Bayesian analysis employing the tidal deformability observational data of the GW170817 and GW190425 binary mergers. We consider two extreme states of strange quark matter, either in nonsuperfluid or color-flavor locked (CFL) and find the results in these two cases essentially reconcile. In particular, our results indicate that the sound speed in the SQS matter is approximately a constant close to the conformal limit of $c/\sqrt{3}$. The universal relations between the mass, the tidal deformability and the compactness are provided for the SQSs. The most probable values of the maximum mass are found to be $M_{\rm TOV}=2.10_{-0.12}^{+0.12}~(2.15_{-0.14}^{+0.16})\,M_{\odot}$ for normal (CFL) SQSs at a $90\%$ confidence level. The corresponding radius and tidal deformability for a $1.4\,M_{\odot}$ star are $R_{\rm 1.4}= 11.50_{-0.55}^{+0.52}~({11.42}_{-0.44}^{+0.52})~\rm km$ and $Λ_{1.4}= {650}_{-190}^{+230}~({630}_{-150}^{+220})$, respectively. We also investigate the possibility of GW190814's secondary component $m_2$ of mass $2.59_{-0.09}^{+0.08}\,M_{\odot}$ being an SQS, and find that it could be a CFL SQS with the pairing gap $Δ$ larger than $244~\rm MeV$ and the effective bag parameter $B_{\rm eff}^{1/4}$ in the range of $170$ to $192$ MeV, at a $90\%$ confidence level.

astro-ph.HE↗

arXiv2021

Bayesian nonparametric inference of neutron star equation of state via neural network

We develop a new nonparametric method to reconstruct the Equation of State (EoS) of Neutron Star with multimessenger data. As an universal function approximator, the Feed-Forward Neural Network (FFNN) with one hidden layer and a sigmoidal activation function can approximately fit any continuous function. Thus we are able to implement the nonparametric FFNN representation of the EoSs. This new representation is validated by its capabilities of fitting the theoretical EoSs and recovering the injected parameters. Then we adopt this nonparametric method to analyze the real data, including mass-tidal deformability measurement from the Binary Neutron Star (BNS) merger Gravitational Wave (GW) event GW170817 and mass-radius measurement of PSR J0030+0451 by {\it NICER}. We take the publicly available samples to construct the likelihood and use the nested sampling to obtain the posteriors of the parameters of FFNN according to the Bayesian theorem, which in turn can be translated to the posteriors of EoS parameters. Combining all these data, for a canonical 1.4 $M_\odot$ neutron star, we get the radius $R_{1.4}=11.83^{+1.25}_{-1.08}$ km and the tidal deformability $Λ_{1.4} = 323^{+334}_{-165}$ (90\% confidence interval).Furthermore, we find that in the high density region ($\geq 3ρ_{\rm sat}$), the 90\% lower limits of the $c_{\rm s}^2/c^2$ ($c_{\rm s}$ is the sound speed and $c$ is the velocity of light in the vacuum) are above $1/3$, which means that the so-called conformal limit (i.e., $c_{\rm s}^2/c^2<1/3$) is not always valid in the neutron stars.

hep-ph↗

arXiv2021

Constraint on phase transition with the multimessenger data of neutron stars

The equation of state (EoS) of the neutron star (NS) matter remains an enigma. In this work we perform the Bayesian parameter inference with the gravitational wave data (GW170817) and mass-radius observations of some NSs (PSR J0030+0451, PSR J0437-4715, and 4U 1702-429) using the phenomenologically constructed EoS models to search for a potential first-order phase transition. Our phenomenological EoS models take the advantages of current widely used parametrizing methods, which are flexible enough to resemble various theoretical EoS models. We find that the current observation data are still not informative enough to support/rule out phase transition, due to the comparable evidences for models with and without phase transition. However, the bulk properties of the canonical $1.4\,M_\odot$ NS and the pressure at around $2ρ_{\rm sat}$ are well constrained by the data, where $ρ_{\rm sat}$ is the nuclear saturation density. Moreover, strong phase transition at low densities is disfavored, and the $1σ$ lower bound of transition density is constrained to $1.84ρ_{\rm sat}$.

astro-ph.HE↗

arXiv2020

Strong post-merger gravitational radiation of GW170817-like events

The post-merger gravitational wave (GW) radiation of the remnant formed in the binary neutron star (BNS) coalescence has not been directly measured, yet. We show in this work that the properties of the BNS involved in GW170817, additionally constrained by PSR J0030+0451, the lower limit on the maximum gravitational mass of non-rotating neutron star (NS) and some nuclear data, are in favor of strong post-merger GW radiation. This conclusion applies to the mergers of Galactic BNS systems as well. Significant post-merger GW radiation is also preferred to improve the consistency between the maximum gravitational mass of the non-rotating NS inferred from GW170817/GRB170817A/AT2017gfo and the latest mass measurements of pulsars. The prominent post-merger gravitational radiation of GW170817-like events are expected to be detectable by advanced LIGO/Virgo detectors in the next decade and then shed valuable lights on the properties of the matter in the extremely high density.

astro-ph.HE↗

arXiv2020

Maximum mass cutoff in the neutron star mass distribution and the prospect of forming supramassive objects in the double neutron star mergers

The sample of neutron stars with a measured mass is growing quickly. With the latest sample, we adopt both a flexible Gaussian mixture model and a Gaussian plus Cauchy-Lorentz component model to infer the mass distribution of neutron stars and use the Bayesian model selection to explore evidence for multimodality and a sharp cutoff in the mass distribution. The two models yield rather similar results. Consistent with previous studies, we find evidence for a bimodal distribution together with a cutoff at a mass of $M_{\rm max}=2.26_{-0.05}^{+0.12}M_\odot$ (68% credible interval; for the Gaussian mixture model). If such a cutoff is interpreted as the maximum gravitational mass of nonrotating cold neutron stars, the prospect of forming supramassive remnants is found to be quite promising for the double neutron star mergers with a total gravitational mass less than or equal to 2.7$M_\odot$ unless the thermal pions could substantially soften the equation of state for the very hot neutron star matter. These supramassive remnants have a typical kinetic rotational energy of approximately $1-2\times 10^{53}$ ergs. Together with a high neutron star merger rate approximately $10^{3}~{\rm Gpc^{-3}~yr^{-3}}$, the neutron star mergers are expected to be significant sources of EeV($10^{18}$eV) cosmic-ray protons.

astro-ph.HE↗

arXiv2020

PSR J0030+0451, GW170817 and the nuclear data: joint constraints on equation of state and bulk properties of neutron stars

Very recently the NICER collaboration has published the first-ever accurate measurement of mass and radius together for PSR J0030+0451, a nearby isolated quickly-rotating neutron star (NS). In this work we set the joint constraints on the equation of state (EoS) and some bulk properties of NSs with the data of PSR J0030+0451, GW170817 and some nuclear experiments. The piecewise polytropic expansion method and the spectral decomposition method have been adopted to parameterize the EoS. The resulting constraints are consistent with each other. Assuming the maximal gravitational mass of non-rotating NS $M_{\rm TOV}$ lies between $2.04 \rm M_{\odot}$ and $2.4 \rm M_{\odot}$, with the piecewise method the pressure at twice nuclear saturation density is measured to be $3.38^{+2.43}_{-1.50}\times 10^{34}~{\rm dyn~cm^{-2}}$ at the $90\%$ level. For a NS with canonical mass of $1.4 \rm M_\odot$, we have the moment of inertia $I_{1.4} = {1.43}^{+0.28}_{-0.13} \times 10^{38}~{\rm kg \cdot m^2}$, tidal deformability $Λ_{1.4} = 390_{-140}^{+320}$, radius $R_{1.4} = 12.2_{-0.9}^{+1.0}~{\rm km}$, and binding energy $BE_{1.4} = {0.16}^{+0.01}_{-0.02} \rm M_{\odot}$ at the $90\%$ level, which are improved in comparison to the constraints with the sole data of GW170817.

astro-ph.HE↗

arXiv2020

Estimating the maximum gravitational mass of nonrotating neutron stars from the GW170817/GRB 170817A/AT2017gfo observation

Assuming that the differential rotation of the massive neutron star (NS) formed in the double NS (DNS) mergers has been effectively terminated by the magnetic braking and a uniform rotation has been subsequently established (i.e., a supramassive NS is formed), we analytically derive in this work an approximated expression for the critical total gravitational mass ($M_{\rm tot,c}$) to form supramassive NS (SMNS) in the DNS mergers, benefited from some equation of state (EoS) insensitive relationships. The maximum gravitational mass of the nonrotating NSs ($M_{\rm TOV}$) as well as the dimensionless angular momentum of the remnant ($j$) play the dominant roles in modifying $M_{\rm tot,c}$, while the radius and mass differences of the premerger NSs do not. The GW170817/GRB 170817A/AT2017gfo observations have provided so far the best opportunity to quantitatively evaluate $M_{\rm TOV}$. Supposing the central engine for GRB 170817A is a black hole quickly formed in the collapse of an SMNS, we find $M_{\rm TOV}=2.13^{+0.09}_{-0.08}M_\odot$ (68.3% credibility interval, including also the uncertainties of the EoS insensitive relationships), which is consistent with the constraints set by current NS mass measurements.

astro-ph.HE↗

arXiv2020

Is GW190425 consistent with being a neutron star$-$black hole merger?

GW190425 is the second neutron star merger event detected by the Advanced LIGO/Virgo detectors. If interpreted as a double neutron star merger, the total gravitational mass is substantially larger than that of the binary systems identified in the Galaxy. In this work we analyze the gravitational-wave data within the neutron star$-$black hole merger scenario. For the black hole, we yield a mass of $2.40^{+0.36}_{-0.32}M_\odot$ and an aligned spin of $0.141^{+0.067}_{-0.064}$. As for the neutron star we find a mass of $1.15^{+0.15}_{-0.13}M_\odot$ and the dimensionless tidal deformability of $1.4^{+3.8}_{-1.2}\times 10^{3}$. These parameter ranges are for 90\% credibility. The inferred masses of the neutron star and the black hole are not in tension with current observations and we suggest that GW190425 is a viable candidate of a neutron star$-$black hole merger event. Benefitting from the continual enhancement of the sensitivities of the advanced gravitational detectors and the increase of the number of the observatories, similar events are anticipated to be much more precisely measured in the future and the presence of black holes below the so-called mass gap will be unambiguously clarified. If confirmed, the mergers of neutron stars with (quickly rotating) low-mass black holes are likely important production sites of the heaviest r-process elements.

astro-ph.HE↗

arXiv2020

The Masses of Isolated Neutron Stars Inferred from the Gravitational Redshift Measurements

For some neutron stars (NSs) in the binary systems, the masses have been accurately measured. While for the isolated neutron stars (INSs), no mass measurement has been reported yet. The situation will change soon thanks to the successful performance of the Neutron Star Interior Composition Explorer (NICER), with which the radius and mass of the isolated PSR J0030+0451 can be simultaneously measured. For most INSs, no mass measurements are possible for NICER because of observational limitations. Benefiting from recent significant progress made on constraining the equation of state of NSs, in this work we propose a way to estimate the masses of the INSs with the measured gravitational redshifts. We apply our method to RX J1856.5-3754, RX J0720.4-3125, and RBS 1223, three members of "The Magnificent Seven" (M7), and estimate their masses to be $1.24_{-0.29}^{+0.29}M_{\odot}$, $1.23_{-0.05}^{+0.10}M_{\odot}$, and $1.08_{-0.11}^{+0.20}M_{\odot}$, respectively. These masses are consistent with that of binary NS systems, suggesting no evidence for experiencing significant accretion of these isolated objects.

astro-ph.HE↗