高能暂现源 · 每日文献综述

We explore the dynamics of neutron star binaries that approach their final inspiral stages with residual eccentricity and strong magnetic fields, features that can arise in systems formed through dynamical capture of relatively young neutron stars. Our analysis focuses on identifying magnetic field imprints on the gravitational-wave signal arising from two mechanisms: magnetic interaction between the neutron stars and electromagnetic radiation from the system's effective dipole. Using a perturbative approach, we obtain the associated gravitational-wave energy-loss rate and phase evolution, and quantify detectability through cumulative dephasing, horizon distances, and Fisher-matrix analyses. While magnetic effects are intrinsically small, entering at 2 post-Newtonian order, their cumulative influence over extended inspirals will become distinguishable in future detectors owing to enhanced low-frequency sensitivity. For binaries with comparable magnetic fields, we show that 10<SUP>14</SUP> G systems will be detectable up to ∼10 Mpc with DECIGO and the Einstein Telescope, while 10<SUP>15</SUP> G fields will be discernible out to several hundred megaparsecs. For extreme fields of 10<SUP>16</SUP> G, third-generation detectors could probe out to gigaparsec scales. These findings suggest that magnetic effects in compact binaries can indeed become observable with next-generation detectors, offering a potential probe of magnetar-level fields and binary formation pathways.

In the past decades, heavy-ion collisions (HIC) at intermediate energies have allowed to probe the nuclear equation-of-state (EoS) of both symmetric and asymmetric nuclear matter over a broad range of densities. In particular, flow has proven to be a powerful observable. Combining the symmetry energy and the symmetric nuclear matter constraints of the EoS from HIC allowed to predict a density dependence of the pressure in a neutron star, up to about 2.5 times saturation density (n<SUB>sat</SUB>), which agrees with recent astronomical measurements deduced from gravitational waves and pulsar observations. So far, the accuracy from HIC expectations is comparable to the latter up to 1.5 n<SUB>sat</SUB>. In these studies, a fundamental aspect is the determination of the profile of densities that are probed by experimental observables used to constrain the EoS. In the near future, new experiments like ASY-EOS performed at higher incident energy and with better accuracy will push further the frontier of the knowledge of the symmetry energy at higher density. These efforts cannot be conclusive without a reliable uncertainty determination, which is related to the reliability of transport model dependencies. Improvements and breakthroughs in transport model simulations and nuclear theory are therefore expected in a joint effort towards HIC contributions to the field of neutron-star physics, including the contribution of strangeness and of the QCD phase transition.

Numerical studies of core-collapse supernovae have demonstrated the importance of nonradial motions in precollapse progenitors on the explosion outcome. We use the CHIMERA neutrino radiation hydrodynamics code running seven two-dimensional simulations of 15 M<SUB>⊙</SUB> progenitors with different progenitor structures introduced by different one- and two-dimensional precollapse stellar evolution environments to examine the impacts of stellar structure and nonspherical motion in the precollapse progenitor on the development of explosions. We compare the explosion evolution of these models in terms of shock dynamics, diagnostic energy, neutrino heating, accretion, explosion geometry, nuclear abundances, and turbulent convection. We also analyze how stochastic variation impacts our simulations. Contrary to results reported in prior studies examining the impacts of multidimensional progenitors, we observe similar shock revival times and explosion development in our simulations despite differences in initial compositions and structures. We find no discernible impact from the accretion of nonradial perturbations from a multi-D progenitor onto the stalled shock in the revival and strength of explosion, as fully developed neutrino-driven convection behind the stalled shock is similar for all our models. For models with physically sourced noise in the iron core, a strong oscillation of the shock occurs after bounce and deflects infall laterally, and accelerates the saturation of the lateral turbulent kinetic energy. An examination of model stochasticity shows that any prior expected impacts on explosive outcome due to convection-related perturbations lie below the detectable threshold of numerical variation.