论文标题
旋转常规黑洞和无抗衡空间的光子环结构
Photon ring structure of rotating regular black holes and no-horizon spacetimes
论文作者
论文摘要
Kerr黑色的黑洞分别具有带有术前和逆行轨道半径的光子区域，$ M \ M \ leq r_p^ - \ leq 3M $和$ 3M \ leq r_p^+\ leq 4M $，因此总是施放封闭的光子环或一个封闭的光子环或一个Shadow shadow silhouette，以$ a \ leq m $。对于$ a> m $，它是一个无野体的时空（裸奇异），其中prograild旋转到中央奇异性，而逆行轨道产生了类似弧形的阴影，中央有一个黑暗的斑点。我们将Kerr黑洞的光子环结构与三个旋转的常规空间产生的光子结构进行比较。 Bardeen，Hayward和非语言。这些是非Kerr黑洞指标，其额外的偏差参数为$ G $，与非线性电动力学费用有关。事实证明，对于给定的$ a $，存在$ g $，$ g_e $的临界值，因此$δ= 0 $对$ g> g_e $没有零，一个双重零，分别为$ r = r_e $ for $ g = g_e $，与无兴奋的空间和极端的黑孔相关，并与重量级的极端黑洞相通用。我们证明，与Kerr裸露的奇异性不同，当$ g_e <g \ leq g_c $，例如，$ a = 0.1亿美元，bardeen（$ g_e = 0.763332m <g \ g \ g \ leq leq g_c = 0.81692m $ $ $ $ $ $ $），无原来的空间可以具有封闭的光子环。 g \ leq g_c = 1.164846m $）和非词（$ g_e = 1.2020m <g \ leq g_c = 1.222461m $）no-horizon pactetimes已关闭光子环。这些结果证实，仅封闭光子环的存在并不能证明紧凑的物体必然是黑洞。根据M87* Black Hole Shadow观测值，三个无原子旋转空间的环圆偏差可观察到的$ΔC$满足$ΔC\ leq 0.10 $。我们还附加了具有类似功能的Kerr-Newman无抗衡空位（裸奇异点）的情况。
The Kerr black holes possess a photon region with prograde and retrograde orbits radii, respectively, $M\leq r_p^-\leq 3M$ and $3M\leq r_p^+\leq 4M$, and thereby always cast a closed photon ring or a shadow silhouette for $a\leq M$. For $a>M$, it is a no-horizon spacetime (naked singularity) wherein prograde orbits spiral into the central singularity, and retrograde orbits produce an arc-like shadow with a dark spot at the center. We compare Kerr black holes' photon ring structure with those produced by three rotating regular spacetimes, viz. Bardeen, Hayward, and nonsingular. These are non-Kerr black hole metrics with an additional deviation parameter of $g$ related to the nonlinear electrodynamics charge. It turns out that for a given $ a $, there exists a critical value of $ g $, $g_E$ such that $Δ=0$ has no zeros for $ g > g_E$, one double zero at $ r = r_E $ for $ g = g_E $, respectively, corresponding to a no-horizon regular spacetime and extremal black hole with degenerate horizon. We demonstrate that, unlike the Kerr naked singularity, no-horizon regular spacetimes can possess closed photon ring when $g_E< g \leq g_c$, e.g., for $a=0.10M$, Bardeen ($g_E=0.763332M<g\leq g_c= 0.816792M$), Hayward ($g_E=1.05297M < g\leq g_c = 1.164846M$) and nonsingular ($g_E=1.2020M < g \leq g_c= 1.222461M$) no-horizon spacetimes have closed photon ring. These results confirm that the mere existence of a closed photon ring does not prove that the compact object is necessarily a black hole. The ring circularity deviation observable $ΔC$ for the three no-horizon rotating spacetimes satisfy $ΔC\leq 0.10$ as per the M87* black hole shadow observations. We have also appended the case of Kerr-Newman no-horizon spacetimes (naked singularities) with similar features.
