标题： Weyl几何引力中的致密星体结构 显示英文标题

标题： Compact stellar structures in Weyl geometric gravity

摘要： 我们考虑在共形不变的Weyl几何引力理论中，特定类型的中子星、夸克星和玻色-爱因斯坦凝聚星的结构和物理性质。 基本理论来自于最简单的共形不变作用量，该作用量分别由Weyl标量的平方、Weyl矢量的强度和物质项构成。 通过引入一个辅助标量场，作用量在Weyl标量上进行线性化。 为了保持理论的共形不变性，在物质能量动量张量上施加了迹条件。 通过相对于度规张量、Weyl矢量场和标量场变分作用量来推导场方程。 通过采用静态球对称的内部几何结构，我们得到了描述Weyl几何引力中天体结构和特性的场方程。 对于中子物质和夸克物质的不同状态方程，场方程的解是数值求解的。 更具体地说，常密度恒星模型，以及由刚性流体、辐射流体、夸克袋模型和玻色-爱因斯坦凝聚状态方程描述的模型，在广义相对论和Weyl几何引力中都被显式地数值构造出来，从而允许对这两种引力理论的预测进行深入比较。 作为一般结果，发现对于所有考虑的状态方程，Weyl几何引力中的恒星比其广义相对论对应的恒星质量更大。 作为获得结果的一个可能天体物理应用，我们建议最近观测到的中子星，其质量分别为2$M_{\odot}$和3$M_{\odot}$，实际上可能是共形不变的Weyl几何中子星或夸克星。 显示英文摘要

摘要： We consider the structure and physical properties of specific classes of neutron, quark, and Bose-Einstein Condensate stars in the conformally invariant Weyl geometric gravity theory. The basic theory is derived from the simplest conformally invariant action, constructed, in Weyl geometry, from the square of the Weyl scalar, the strength of the Weyl vector, and a matter term, respectively. The action is linearized in the Weyl scalar by introducing an auxiliary scalar field. To keep the theory conformally invariant the trace condition is imposed on the matter energy-momentum tensor. The field equations are derived by varying the action with respect to the metric tensor, Weyl vector field and scalar field. By adopting a static spherically symmetric interior geometry, we obtain the field equations, describing the structure and properties of stellar objects in Weyl geometric gravity. The solutions of the field equations are obtained numerically, for different equations of state of the neutron and quark matter. More specifically, constant density stellar models, and models described by the stiff fluid, radiation fluid, quark bag model, and Bose-Einstein Condensate equations of state are explicitly constructed numerically in both general relativity and Weyl geometric gravity, thus allowing an in depth comparison between the predictions of these two gravitational theories. As a general result it turns out that for all the considered equations of state, Weyl geometric gravity stars are more massive than their general relativistic counterparts. As a possible astrophysical application of the obtained results we suggest that the recently observed neutron stars, with masses in the range of 2$M_{\odot}$ and 3$M_{\odot}$, respectively, could be in fact conformally invariant Weyl geometric neutron or quark stars.