تقرير
Impact of bulk viscosity on the post-merger gravitational-wave signal from merging neutron stars
| العنوان: | Impact of bulk viscosity on the post-merger gravitational-wave signal from merging neutron stars |
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| المؤلفون: | Chabanov, Michail, Rezzolla, Luciano |
| سنة النشر: | 2023 |
| المجموعة: | Astrophysics General Relativity and Quantum Cosmology Nuclear Theory |
| مصطلحات موضوعية: | General Relativity and Quantum Cosmology, Astrophysics - High Energy Astrophysical Phenomena, Nuclear Theory |
| الوصف: | In the violent post-merger of binary neutron-star mergers strong oscillations are present that impact the emitted gravitational-wave (GW) signal. The frequencies, temperatures and densities involved in these oscillations allow for violations of the chemical equilibrium promoted by weak-interactions, thus leading to a nonzero bulk viscosity that can impact dynamics and GW signals. We present the first simulations of binary neutron-star mergers employing the self-consistent and second-order formulation of the equations of relativistic hydrodynamics for dissipative fluids proposed by M\"uller, Israel and Stewart. With the spirit of obtaining a first assessment of the impact of bulk viscosity on the structure and radiative efficiency of the merger remnant we adopt a simplified approach for the viscosity, which we assume to be constant within the stars, but which we vary in strength for different binaries, thus exploring the possible behaviours and obtaining strict upper limits. In this way, we find that large bulk viscosities are very effective at damping the collision-and-bounce oscillations that characterize the dynamics of the stellar cores right after the merger. As a result, the $m=2$ deformations and the gravitational-radiation efficiency of the remnant are considerably reduced, with qualitative and quantitative changes in the post-merger spectrum that can be large in the case of the most extreme configurations. Overall, our crude but self-consistent results indicate that bulk viscosity reduces the energy radiated in GWs by $\lesssim 1\%$ in the (realistic) scenario of small viscosity, and by $\lesssim 15\%$ in the (unrealistic) scenario of large viscosity. Comment: 8 pages, 2 figures |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2307.10464 |
| رقم الأكسشن: | edsarx.2307.10464 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |