论文标题
Axion $ f（R）$ GRAVITY中的超质量中子星星
Supermassive Neutron Stars in Axion $F(R)$ Gravity
论文作者
论文摘要
我们研究了轴$ r^{2} $重力中的现实中子星。曲率和轴向字段$ ϕ $之间的耦合在简单的表格$ \ sim r^2ϕ $中。对于范围内的轴质量，$ m_ {a} \ sim 10^{ - 11} -10^{ - 10} $ ev中子星中的词素核心和尺寸$ \ sim 100 $ km的相应halo可能存在。因此，$ r^2 $项的有效贡献在恒星内生长，并导致恒星参数的变化（即质量和半径）。我们获得了与中央密度无关的恒星质量的增加，以范围广泛的质量。因此，给定状态方程增长的最大质量。同时，与GR相比，恒星半径并不大。 {因此，我们的模型可能会预测具有质量$ M \ sim 2.2-2.2-2.2.2-2.2.2-2.2m_ \ odot $和radii $ r_ {s} \ sim 11 $ km的状态方程的超级质量紧凑型恒星可能存在（我们考虑了APR方程式）。总的来说，相对性可以获得具有此类特征的中子星，仅用于不现实的状态方程。}请注意，由于恒星外的标量曲率的溶液的变化，质量的增加发生。在GR曲率中，在$ρ= p = 0 $的恒星表面下降至零。在正在考虑的模型中，与真空$ r^2 $重力相比，标量曲率转储更慢，这是由于恒星周围的轴“ galo”引起的。
We investigated realistic neutron stars in axion $R^{2}$ gravity. The coupling between curvature and axion field $ϕ$ is assumed in the simple form $\sim R^2ϕ$. For the axion mass in the range $m_{a}\sim 10^{-11}-10^{-10}$ eV the solitonic core within neutron star and corresponding halo with size $\sim 100$ km can exist. Therefore the effective contribution of $R^2$ term grows inside the star and it leads to change of star parameters (namely, mass and radius). We obtained the increase of star mass independent from central density for wide range of masses. Therefore, maximal possible mass for given equation of state grows. At the same time, the star radius increases not so considerably in comparison with GR. {Hence, our model may predict possible existence of supermassive compact stars with masses $M\sim 2.2-2.3M_\odot$ and radii $R_{s}\sim 11$ km for realistic equation of state (we considered APR equation of state). In General Relativity one can obtain neutron stars with such characteristics only for unrealistic, extremely stiff equations of state.} Note that this increase of mass occurs due to change of solution for scalar curvature outside the star. In GR curvature drops to zero on star surface where $ρ=p=0$. In the model under consideration the scalar curvature dumps more slowly in comparison with vacuum $R^2$ gravity due to axion "galo" around the star.
