论文标题
在有共同移动观察者的等离子体存在下，科特勒黑洞的阴影
Shadow of Kottler black hole in the presence of plasma for a co-moving observer
论文作者
论文摘要
我们考虑在（3+1） - 维度中的球形对称黑洞指标，存在正宇宙常数$λ$。我们使用\ cite {1}中提出的一般方法来转换共同移动坐标中的度量。然后，对于一般度量，我们已经评估了在不存在和存在血浆的情况下的角阴影尺寸。通过使用畸变关系，我们找到了Schwarzschild De-Sitter或Kottler SpaceTime的共同移动观察者所观察的相应的阴影半径。详细观察到了宇宙学常数$λ$和等离子参数$ k $对黑洞阴影的角度大小的影响。最后，通过使用M87 $^*$的观察到的角度大小和sgr a $^*$黑洞，我们用特定的观察值$ k $限制了宇宙常数$λ$的特定观察值（或Hubble常数$ H_0 $）。
We consider a spherically symmetric black hole metric in (3+1)-dimensions in presence of a positive cosmological constant $Λ$. We use a general approach as proposed in \cite{1} to transform the metric in co-moving coordinates. Then for a general metric we have evaluated the angular shadow size both in absence and presence of plasma. By using the aberration relation, we then find the corresponding shadow radius as viewed by a co-moving observer for Schwarzschild de-Sitter or Kottler spacetime. The effect of cosmological constant $Λ$ and plasma parameter $k$ on the angular size of black hole shadow has been observed in detail. Finally, by using the observed angular size of M87$^*$ and Sgr A$^*$ black hole, we constrain the value of the plasma parameter $k$ with a specific observational value of the cosmological constant $Λ$ (or the Hubble constant $H_0$).
