arXiv subjects

Zidu Lin

Publications and source records attributed to Zidu Lin.

At least 19 recordsLinked to original sources

arXiv2026

Joint Detection and Characterization of the Standing Accretion Shock Instability for Core-Collapse Supernovae with cWB XP

The most sensitive to-date multimessenger detection of the standing accretion shock instability in real interferometric data is presented, which quantitatively identifies the presence of the SASI in core-collapse supernovae using neutrino and gravitational-wave (GW) signals. In the GW channel, the coherent WaveBurst (cWB) software on its version XP is implemented, among with real LIGO data from the O3 and O4 observing runs. With this, a more accurate estimation of parameters, such as the central frequency and signal duration, is obtained for both sets of data. The SASI identification probability versus false alarm rates is presented in the form of Receiver Operating Characteristic (ROC) curves. For O3, the new study for the combined GW and neutrino detection condition, labeled as $x + y$, shows an identification probability (previous best results from Lin et al. [1]) of 1 (1), 0.90 (0.70) and 0.37 (0.34) at 1, 5 and 10 kpc for a false identification probability of 0.10. On the other hand, using O4 shows that the GW channel by itself is sensitive enough to provide almost perfect identification probability scores, with identification probability values of 1, 0.99 and 0.97 for a false identification probability of 0.01 at 1, 5 and 10 kpc, respectively.

astro-ph.HE↗

arXiv2026

Neutrino flavor instabilities in neutron star mergers with moment transport: Slow, fast, and collisional modes

Determining where, when, and how neutrino flavor oscillations must be included in large-scale simulations of hot and dense astrophysical environments is an enduring challenge that must be tackled to obtain accurate predictions. Using an angular moment-based linear stability analysis framework, we examine the different kinds of flavor instabilities that can take place in the context of the post-processing of a neutron star merger simulation, with a particular focus on the collisional flavor instability and a careful assessment of several commonly used approximations. First, neglecting anisotropies of the neutrino field, we investigate the extent to which commonly used monoenergetic growth rates reproduce the results obtained from a full multi-energy treatment. Contrary to the large discrepancies found in core-collapse supernova environments, we propose a simple combination of energy-averaged estimates that reproduces the multi-energy growth rates in our representative simulation snapshot. We then quantify the impact of additional physical effects, including nuclear many-body corrections, scattering opacities, and the inclusion of the vacuum term in the neutrino Hamiltonian. Finally, we include the neutrino distribution anisotropies, which allows us to explore, for the first time in a multi-energy setting, the interplay between collisional, fast, and slow modes in a moment-based neutron star merger simulation. We find that, despite a dominance of the fast instability in most of the simulation volume, certain regions exhibit only a collisional instability, while others, especially at large distances, exhibit a slow instability that is largely underestimated if anisotropic effects are neglected.

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arXiv2025

Recurring region for neutron-star observables

In this letter, we report a novel, somewhat analytical way to produce equations of state (EOSs) that generate particular values of neutron star mass, radius, and tidal deformability. This is possible because our description for the EoS of dense matter can produce recurring regions, small areas where several EoSs cross in the mass-radius and mass-tidal deformability diagrams. We can place recurring regions in desired locations of these diagrams, corresponding e.g., to a given observation. Our prescription is versatile, in the sense that different microscopic models can be used for the low density hadronic phase and high density quark phase, as long as they are connected by a percolation, a description that mimics quark deconfinement and is motivated by QCD. The several EoSs that pass by a recurring region can present different thresholds for the boundaries of the percolation region (different beginning and ending for the quark deconfinement region), as well as different orders for the phase transition at the boundaries. When combining all these features, our prescription allows one not only to produce an EoS that matches an observation, but also one that matches specific chosen criteria for the EoS. The EoSs produced by this new method will be specially suitable for the study of dense-matter properties in future gravitational-wave observations, when both the inspiral and post-merger phase signals will become available. Our numerical code that calculates recurring regions using CompOSE microscopic EoSs is open source and publicly available.

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arXiv2025

Bayesian Inference of the Landau Parameter $G'_0$ from Joint Gamow-Teller Measurements

The Landau-Migdal parameter $G'_0$ characterizes the main part of the spin-isospin dependent nucleon-nucleon interaction. Consequently, the $G'_0$ is closely related to the Gamow-Teller resonance (GTR), the beta and double-beta decay rates of finite nuclei, the response of hot and dense nucleonic matter that modifies the neutrino-nucleon absorption rates in core-collapse supernovae (CCSNe) and binary neutron star (BNS) mergers, and finally the critical density for pion condensation in neutron stars. In this letter, for the first time, we report the $G'_0$ with quantified uncertainty in the framework of Bayesian inference, using a self-consistent standard Skyrme Random Phase Approximation (RPA) model and joint constraints from experimental GTR measurements on $^{208}\mathrm{Pb}$, $^{132}\mathrm{Sn}$, $^{90}\mathrm{Zr}$. Our extracted $G_0'$ is $0.48\pm0.034$, which is close to the prediction of a few existing Skyrme models that consider spin-isospin observables but smaller than the traditional ones extracted from pion-exchange models. We hint to possible reasons for this deviation, like the value of the nucleon effective mass $\frac{m^*}{m}$. The $G_0'$ values extracted in this work may guide the construction of new energy density functionals that aims to self-consistently describe the dense matter properties in the spin-isospin channel.

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arXiv2025

Towards constraining QCD phase transitions in neutron star interiors: Bayesian Inference with TOV linear response analysis

The potential hadron-to-quark phase transition in neutron stars has not been fully understood as the property of cold, dense, and strongly interacting matter cannot be theoretically described by the first-principle perturbative calculations, nor have they been systematically measured through terrestrial low-to-intermediate energy heavy-ion experiments. Given the Tolman--Oppenheimer--Volkoff (TOV) equations, the equation of state (EoS) of the neutron star (NS) matter can be constrained by the observations of NS mass, radius, and tidal deformability. However, large observational uncertainties and the limited number of observations currently make it challenging to strictly reconstruct the EoS, especially to identify interesting features such as a strong first-order phase transition. In this work, we study the dependency of reconstruction quality of the phase transition on the number of NS observations of mass and radius as well as their uncertainty, based on a fiducial EoS. We conquer this challenging problem by constructing a neural network, which allows one to parametrize the EoS with minimum model-dependency, and by devising an algorithm of parameter optimization based on the analytical linear response analysis of the TOV equations. This work may pave the way for the understanding of the phase transition features in NSs using future $x$-ray and gravitational wave measurements.

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arXiv2024

Characterizing the nuclear models informed by PREX and CREX: a view from Bayesian inference

New measurements of the weak charge density distributions of $^{48}$Ca and $^{208}$Pb challenge existing nuclear models. In the post-PREX-CREX era, it is unclear if current models can simultaneously describe weak charge distributions along with accurate measurements of binding energy and charge radii. In this letter, we explore the parameter space of relativistic and non-relativistic models to study the differences between the electric and weak form factors, $\Delta F=F_{ch}-F_{W}$, in $^{48}$Ca and $^{208}$Pb. We show, for the first time, which aspects of mean-field models are the most important in determining the relative magnitude of the neutron skin in lead and calcium nuclei. We carefully disentangle the tension between the PREX-2/CREX constraints and the ability of the RMF and Skyrme models to accurately describe binding energies and charge radii. We find that the nuclear symmetry energy coefficient $S_V$ and the isovector spin-orbit coefficient $b'_4$ play different roles in determining $\Delta F$ of $^{48}$Ca and $^{208}$Pb. Consequently, adjusting $S_V$ or $b'_4$ shifts predicted $\Delta F$ values toward or away from PREX-2/CREX measurements. Additionally, $S_V$ and the slope L are marginally correlated given the prior constraints of our Bayesian inference, allowing us to infer them separately from PREX-2/CREX data.

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arXiv2023

Indication of Sharp and Strong Phase-Transitions from NICER Observations

In this letter, we present a new, weakly model-dependent, test for ``standard" equations of state (EoS) models that disfavor sharp and strong phase-transitions, by using neutron star mass and radius observations. We show the radii of two neutron stars observed by NICER (PSR J0740+6620 and PSR 0030+0451) are correlated if these two neutron stars are built upon standard EoS models. The radii of neutron stars with different masses are sensitive to the pressures at different densities, and the pressures at different densities are strongly correlated in standard EoS models. We further show that the correlation of the neutron star radii can be significantly weakened, when additional degrees of freedom concerning the first-order phase transitions are added into the EoSs. We propose a new quantity, ${D}_{\mathrm{L}}$, which measures the extent to which the linear correlation of the radii of two neutron stars is weakened. Our method gives a $48\%$ identification probability (with a $5\%$ false alarm rate) of finding beyond standard EoS models in NICER observations. Future observations with higher measurement accuracy can confirm or rule out this identification. Our method is generalizable to any pair of neutron star masses and can be employed with other sets of observations in the future.

astro-ph.HE↗

arXiv2023

Structure Factors for Hot Neutron Matter from Ab Initio Lattice Simulations with High-Fidelity Chiral Interactions

We present the first ab initio lattice calculations of spin and density correlations in hot neutron matter using high-fidelity interactions at next-to-next-to-next-to-leading order (N3LO) in chiral effective field theory. These correlations have a large impact on neutrino heating and shock revival in core-collapse supernovae and are encapsulated in functions called structure factors. Unfortunately, calculations of structure factors using high-fidelity chiral interactions were well out of reach using existing computational methods. In this work, we solve the problem using a computational approach called the rank-one operator (RO) method. The RO method is a general technique with broad applications to simulations of fermionic many-body systems. It solves the problem of exponential scaling of computational effort when using perturbation theory for higher-body operators and higher-order corrections. Using the RO method, we compute the vector and axial static structure factors for hot neutron matter as a function of temperature and density. The ab initio lattice results are in good agreement with virial expansion calculations at low densities but are more reliable at higher densities. Random phase approximation codes used to estimate neutrino opacity in core-collapse supernovae simulations can now be calibrated with ab initio lattice calculations.

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arXiv2023

Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter

This review aims at providing an extensive discussion of modern constraints relevant for dense and hot strongly interacting matter. It includes theoretical first-principle results from lattice and perturbative QCD, as well as chiral effective field theory results. From the experimental side, it includes heavy-ion collision and low-energy nuclear physics results, as well as observations from neutron stars and their mergers. The validity of different constraints, concerning specific conditions and ranges of applicability, is also provided.

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arXiv2022

Characterizing a supernova's Standing Accretion Shock Instability with neutrinos and gravitational waves

We perform a novel multi-messenger analysis for the identification and parameter estimation of the Standing Accretion Shock Instability (SASI) in a core collapse supernova with neutrino and gravitational wave (GW) signals. In the neutrino channel, this method performs a likelihood ratio test for the presence of SASI in the frequency domain. For gravitational wave signals we process an event with a modified constrained likelihood method. Using simulated supernova signals, the properties of the Hyper-Kamiokande neutrino detector, and O3 LIGO Interferometric data, we produce the two-dimensional probability density function (PDF) of the SASI activity indicator and calculate the probability of detection $P_\mathrm{D}$ as well as the false identification probability $P_\mathrm{FI}$. We discuss the probability to establish the presence of the SASI as a function of the source distance in each observational channel, as well as jointly. Compared to a single-messenger approach, the joint analysis results in $P_\mathrm{D}$ (at $P_\mathrm{FI}=0.1$) of SASI activities that is larger by up to $\approx~40\%$ for a distance to the supernova of 5 kpc. We also discuss how accurately the frequency and duration of the SASI activity can be estimated in each channel separately. Our methodology is suitable for implementation in a realistic data analysis and a multi-messenger setting.

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arXiv2022

Uncertainty Quantification for Neutrino Opacities in Core-Collapse Supernovae and Neutron Star Mergers

We perform an extensive study of the correlations between the neutrino-nucleon inverse mean free paths (IMFPs) and the underlying equation of states (EoSs). Strong interaction uncertainties in the neutrino mean free path are investigated in different density regimes. The nucleon effective mass, the nucleon chemical potentials, and the residual interactions in the medium play an important role in determining neutrino-nucleon interactions in a density-dependent manner. We study how the above quantities are constrained by an EoS consistent with (i) nuclear mass measurements, (ii) proton-proton scattering phase shifts, and (iii) neutron star observations. We then study the uncertainties of both the charged current and the neutral current neutrino-nucleon inverse mean free paths due to the variation of these quantities, using Hartree-Fock+random phase approximation method. Finally, we calculate the Pearson correlation coefficients between (i) the EoS-based quantities and the EoS-based quantities; (ii) the EoS-based quantities and the IMFPs; (iii) the IMFPs and the IMFPs. We find a strong impact of residual interactions on neutrino opacity in the spin and spin-isospin channels, which are not well constrained by current nuclear modelings.

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arXiv2022

Detectability of neutrino-signal fluctuations induced by the hadron-quark phase transition in failing core-collapse supernovae

We introduce a systematic and quantitative methodology for establishing the presence of neutrino oscillatory signals due to the hadron-quark phase transition (PT) in failing core-collapse supernovae from the observed neutrino event rate in water- or ice-based neutrino detectors. The methodology uses a likelihood ratio in the frequency domain as a test-statistic; it is employed for quantitative analysis of neutrino signals without assuming the frequency, amplitude, starting time, and duration of the PT-induced oscillations present in the neutrino events and thus it is suitable for analyzing neutrino signals from a wide variety of numerical simulations. We test the validity of this method by using a core-collapse simulation of a 17 solar-mass star by Zha \emph{et al.} (2021). Based on this model, we further report the presence of a PT-induced oscillations quantitatively for a core-collapse supernovae out to a distance of $\sim 10$ kpc, $\sim 5$ kpc for IceCube and to a distance of $\sim 10$ kpc, $\sim 5$ kpc and $\sim 1$ kpc for a 0.4 Mt mass water Cherenkov detector. This methodology will aid the investigation of a future galactic supernova and the study of hadron-quark phase in the core of core-collapse supernovae.

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arXiv2021

Memory-triggered supernova neutrino detection

We demonstrate that observations of the gravitational memory from core collapse supernovae at future Deci-Hz interferometers enable time-triggered searches of supernova neutrinos at Mt-scale detectors. Achieving a sensitivity to characteristic strains of at least $\sim 10^{-25}$ at $f\simeq 0.3$ Hz -- e.g., by improving the noise of DECIGO by one order of magnitude -- will allow robust time triggers for supernovae at distances $D\sim 40-300$ Mpc, resulting in a nearly background-free sample of $\sim 3-70$ neutrino events per Mt per decade of operation. This sample would bridge the sensitivity gap between rare galactic supernova bursts and the cosmological diffuse supernova neutrino background, allowing detailed studies of the neutrino emission of supernovae in the local Universe.

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arXiv2020

Fast neutrino cooling of nuclear pasta in neutron stars: molecular dynamics simulations

The direct URCA process of rapid neutrino emission can occur in nonuniform nuclear pasta phases that are expected in the inner crust of neutron stars. Here, the periodic potential for a nucleon in nuclear pasta allows momentum conservation to be satisfied for direct URCA reactions. We improve on earlier work by modeling a rich variety of pasta phases (gnocchi, waffle, lasagna, and anti-spaghetti) with large-scale molecular dynamics simulations. We find that the neutrino luminosity due to direct URCA reactions in nuclear pasta can be 3 to 4 orders of magnitude larger than that from the modified URCA process in the NS core. Thus neutrino radiation from pasta could dominate radiation from the core and this could significantly impact the cooling of neutron stars

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arXiv2019

Detectability of SASI activity in supernova neutrino signals

We introduce a novel methodology for establishing the presence of Standing Accretion Shock Instabilities (SASI) in the dynamics of a core collapse supernova from the observed neutrino event rate at water- or ice-based neutrino detectors. The methodology uses a likelihood ratio in the frequency domain as a test-statistics; it is also employed to assess the potential to estimate the frequency and the amplitude of the SASI modulations of the neutrino signal. The parameter estimation errors are consistent with the minimum possible errors as evaluated from the inverse of the Fisher information matrix, and close to the theoretical minimum for the SASI amplitude. Using results from a core-collapse simulation of a 15 solar-mass star by Kuroda $\it {et\, al.}$ (2017) as a test bed for the method, we find that SASI can be identified with high confidence for a distance to the supernova of up to $\sim 6$ kpc for IceCube and and up to $\sim 3$ kpc for a 0.4 Mt mass water Cherenkov detector. This methodology will aid the investigation of a future galactic supernova.

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arXiv2019

Observing cosmological binary mergers with next generation neutrino and gravitational wave detectors

We discuss the potential of detecting thermal neutrinos from matter-rich binary mergers, via a decades-long multi-messenger campaign involving a Mt-scale water Cherenkov neutrino detector and one or more next generation gravitational wave detectors, capable of observing mergers up to redshift $z\sim 2$. The search of neutrinos in time-coincidence with gravitational wave detections will allow to identify single neutrinos from individual mergers above the background, and to study their distributions in energy, redshift and type (double neutron-star or neutron-star-black hole merger) of the candidate sources. We find that, for merger rates consistent with current LIGO-Virgo constraints, and for a $100~{\rm Mt\cdot yr}$ exposure, between ${\mathcal O(10^{-1})}$ and ${\mathcal O(10)}$ neutrino events are expected. For extreme cases of mergers with more than $10^{52}$ ergs emitted in $\mathrel{{\bar \nu}_e}$, the number of events can be as large as $\sim 100$, with sensitivity to mergers up to redshift $z\sim 0.5$ or so. Such scenarios can already be tested with a $10~{\rm Mt\cdot yr}$ exposure, resulting in constraints on the post-merger evolution of the systems being considered.

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arXiv2017

Core-Collapse Supernova Simulations including Neutrino Interactions from the Virial EOS

Core-collapse supernova explosions are driven by a central engine that converts a small fraction of the gravitational binding energy released during core collapse to outgoing kinetic energy. The suspected mode for this energy conversion is the neutrino mechanism, where a fraction of the neutrinos emitted from the newly formed protoneutron star are absorbed by and heat the matter behind the supernova shock. Accurate neutrino-matter interaction terms are crucial for simulating these explosions. In this proceedings for IAUS 331, SN 1987A, 30 years later, we explore several corrections to the neutrino-nucleon scattering opacity and demonstrate the effect on the dynamics of the core-collapse supernova central engine via two dimensional neutrino-radiation-hydrodynamics simulations. Our results reveal that the explosion properties are sensitive to corrections to the neutral-current scattering cross section at the 10-20% level, but only for densities at or above $\sim 10^{12}$ g cm$^{-3}$

astro-ph.HE↗

arXiv2017

Deep crustal heating by neutrinos from the surface of accreting neutron stars

We present a new mechanism for deep crustal heating in accreting neutron stars. Charged pions ($\pi^+$) are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. For massive and/or compact neutron stars, neutrinos deposit $\approx 1\textrm{--} 2 \, \mathrm{MeV}$ of heat per accreted nucleon into the inner crust. The strength of neutrino heating is comparable to the previously known sources of deep crustal heating, such as from pycnonuclear fusion reactions, and is relevant for studies of cooling neutron stars. We model the thermal evolution of a transient neutron star in a low-mass X-ray binary, and in the particular case of the neutron star MXB~1659-29 we show that additional deep crustal heating requires a higher thermal conductivity for the neutron star inner crust. A better knowledge of pion production cross sections near threshold would improve the accuracy of our predictions.

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