arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2006.10080gr-qcastro-ph.COastro-ph.HEhep-ph
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高度致密的中子星和屏蔽机制。I.平衡与稳定性

Highly compact neutron stars and screening mechanisms. I. Equilibrium and stability

Bernardo F. de Aguiar, Raissa F. P. Mendes

摘要:

修正后的引力理论为暗能量提供了可行的模型,它们通常依赖于在高密度环境中屏蔽其影响的机制。从这个角度来看,似乎一旦满足太阳系的限制,这些理论将预测(密度更大的)中子星的一个微不足道的现象。在这项工作中,我们探索了这样一个事实:在纯量张量理论中,纯量自由度并不单独与质量密度耦合,而是与能量动量张量的踪迹耦合--随着密度和压力的增加,能量动量张量可以增加并最终改变符号。在中子星的核心,并调查是否可能存在对自然界中发现的最致密恒星内部的标量场的部分非屏蔽。为此,我们构造了具有屏蔽机制的中子星理论状态方程,并研究了它们在径向扰动下的稳定性。特别是,我们发现,稳定的解决方案,一个未屏蔽的核心可以存在于变色龙模型,而环境依赖的变色龙模型的一个新的,标量化的平衡解决方案的财富被发现,其中一些可以是稳定的。

英文摘要:

Modified theories of gravity that offer viable models for dark energy often rely on mechanisms that screen their effects in high density environments. From this perspective, it would appear that, once solar system constraints are satisfied, these theories would predict a trivial phenomenology for (much denser) neutron stars. In this work we explore the fact that in scalar-tensor theories the scalar degree of freedom does not couple to the mass density alone, but to the trace of the energy-momentum tensor - which can increase and eventually change sign as density and pressure build up in the core of neutron stars -, and investigate whether there could be a partial unscreening of the scalar field inside the most compact stars found in Nature. For this purpose, we construct neutron star solutions with realistic equations of state in theories with screening mechanisms and study their stability under radial perturbations. In particular, we find that stable solutions with a unscreened core can exist in chameleon models, while for the environmentally-dependent dilaton model a wealth of new, scalarized equilibrium solutions are found, some of which can be stable.

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