标题： 克尔-标量子度规和银河系中心黑洞附近的天体物理后果 显示英文标题

标题： Kerr-scalaron metric and astronomical consequences near the Galactic Center black hole

摘要： 天体物理测试银河系中心（GC）黑洞Sgr A*附近的时空度规和引力理论，随着对黑洞附近致密恒星轨道的观测和黑洞阴影的测量而获得了动力。 偏离Kerr度规可能是修改引力理论的潜在特征。 在本工作中，我们使用Newman-Janis算法在f(R)标量子引力理论中构建一个轴对称且渐近平坦的度规。 我们称之为Kerr-标量子度规。 为了研究新度规的天体物理后果，我们使用了致密恒星轨道和黑洞阴影。 我们使用GC黑洞阴影的发射环观测大小来估计新度规与广义相对论的偏差。 已经发现质量在$10^{-17}$电子伏特 -$10^{-16}$电子伏特范围内的标量子与黑洞自转$\chi=0.9$的观测发射环大小相容。 我们估计了靠近黑洞的致密恒星轨道的近日点进动的Schwarzschild极限。 包括S星如S4716和S2在内的更宽轨道中的广义相对论近日点进动已通过这些标量子再现。 测量偏离Schwarzschild近日点进动的参数$f_{SP}$在具有半长轴$45$天文单位 -$100$天文单位的恒星轨道中被发现为$f_{SP}=1.00-1.04$。 标量子能够支配远低于$45$天文单位的施瓦茨希尔德进动。 使用新度规估计了紧凑轨道的伦斯-蒂林进动。 大质量标量子在S2轨道上产生大小为 ($12.25-24.5$)$\mu$每年 的伦斯-蒂林进动。 伦斯-蒂林进动的时间尺度在S星年龄的$0.1$% 范围内。 显示英文摘要

摘要： Astronomical tests of spacetime metric and gravitation theory near the Galactic Center (GC) black hole, Sgr A* have gained momentum with the observations of compact stellar orbits near the black hole and measurement of the black hole shadow. Deviation from the Kerr metric is a potential signature of modified gravity theory. In this work, we use Newman-Janis algorithm to construct an axially symmetric and asymptotically flat metric in f(R) scalaron gravity theory. We call it as Kerr-scalaron metric. For studying astronomical consequences of the new metric we use the compact stellar orbits and the black hole shadow. We use the observed size of the emission ring of the GC black hole shadow for estimating deviation of the new metric from general relativity. It has been found that scalarons with mass within $10^{-17}$ eV - $10^{-16}$ eV are compatible with the observed emission ring size for black hole spin $\chi=0.9$. Schwarzschild limit of the pericenter shift is estimated for compact stellar orbits near the black hole. General relativistic pericenter shift in wider orbits including S-stars such as S4716 and S2 has been reproduced with these scalarons. The parameter $f_{SP}$ measuring deviation from Schwarzschild pericenter shift has been found as $f_{SP}=1.00-1.04$ within stellar orbits having semi-major axes $45$ au - $100$ au. Scalarons have the capability to dominate Schwarzschild precession for orbits much below $45$ au. Lense-Thirring (LT) precession with the new metric is estimated for the compact orbits. The massive scalarons produce LT precession with magnitude ($12.25-24.5$) $\mu$as/yr in the orbit of S2. The LT precession time scale is within $0.1$% of the age of the S-stars.