标题： 超紧致矢量星 显示英文标题

标题： Ultracompact vector stars

摘要： 我们解析研究了引力的矢量-张量理论中的一个新的无视界紧致天体家族，称为超紧致矢量星。 它们由一种由矢量凝聚态产生，这种凝聚态是由与引力的非最小耦合引起的。 由于其内部的各向异性应力，它们可以和黑洞一样紧凑。 在球对称情况下，它们的内部类似于等温球，其中的奇点可以通过调整可用的积分常数来解决。 恒星内部平滑地匹配到外部的施瓦西几何，无需在恒星表面添加额外的能量动量张量。 我们分析了恒星内部测地线的行为，其中允许存在稳定的圆形轨道，以及穿越恒星表面的轨迹。 我们解析研究了破坏球对称性的矢量场和几何形状的定态变形，其特征取决于我们考虑的矢量-张量理论。 我们引入并确定了矢量磁化率作为探测恒星性质的探针，并分析了矢量电荷如何影响恒星的旋转速率。 显示英文摘要

摘要： We analytically investigate a new family of horizonless compact objects in vector-tensor theories of gravity, called ultracompact vector stars. They are sourced by a vector condensate, induced by a non-minimal coupling with gravity. They can be as compact as black holes, thanks to their internal anisotropic stress. In the spherically symmetric case their interior resembles an isothermal sphere, with a singularity that can be resolved by tuning the available integration constants. The star interior smoothly matches to an exterior Schwarzschild geometry, with no need of extra energy-momentum tensor at the star surface. We analyse the behaviour of geodesics within the star interior, where stable circular orbits are allowed, as well as trajectories crossing in both ways the star surface. We analytically study stationary deformations of the vector field and of the geometry, which break spherical symmetry, and whose features depend on the vector-tensor theory we consider. We introduce and determine the vector magnetic susceptibility as a probe of the star properties, and we analyze how the rate of rotation of the star is affected by the vector charges.