标题： 均匀等离子体中范德瓦尔斯黑洞的阴影和强引力透镜效应 显示英文标题

标题： Shadows and Strong Gravitational Lensing by Van der Waals Black Hole in Homogeneous Plasma

摘要： 本文首先分析了范德瓦尔斯（VdW）黑洞的视界结构，然后研究了它在无等离子体介质以及存在均匀等离子体介质情况下的阴影。我们发现，范德瓦尔斯参数$a$和$b$对黑洞阴影有显著影响。我们还观察到，在均匀等离子体介质中，阴影半径随着参数$\sigma =\frac{\omega_p}{\omega_{\infty}}$（等离子体频率与光子频率之比）的增加而减小，并且在非均匀等离子体介质中的阴影半径大于真空介质中的阴影半径。此外，我们在均匀等离子体介质中讨论了强引力透镜效应。我们观察到，光球半径、偏转极限系数以及强场中的偏转角受到均匀等离子体介质存在的强烈影响。我们还发现，均匀等离子体介质情况下，范德瓦尔斯黑洞在强场极限下的偏转角大于真空介质中的偏转角。进一步地，我们以强场极限下的超大质量黑洞为例，讨论了均匀等离子体的影响下可观测量的角度位置$\theta_{\infty}$、分离$S$和增益$r_{mag}$。 结论认为，范德华参数$a$、$b$和均匀等离子体介质对阴影和强引力透镜效应均有显著影响。 显示英文摘要

摘要： In this paper, we first analyze the horizon structure of the Van der Waals(VdW) black hole and then investigate its shadow in the absence of a plasma medium as well as the presence of a homogeneous plasma medium. We find that both the Van der Waals parameters $a$ and $b$ have a significant effect on the shadow of the black hole. We also observe that the radius of the shadow in a homogeneous plasma medium decreases while parameter $\sigma =\frac{\omega_p}{\omega_{\infty}}$ ( the ratio of plasma frequency and photon frequency) increases and the radius of the shadow inhomogeneous plasma medium is larger than the vacuum medium. We also discuss the strong gravitational lensing in a homogeneous plasma medium. We observe that the photon sphere radius, deflection limit coefficients and deflection angle in the strong field are highly affected by the presence of a homogeneous plasma medium. We also find that the deflection angle in the strong field limit by the Van der Waals black hole with the homogeneous plasma is greater than that of the Vacuum medium. Further, we discuss the observables quantities angular position $\theta_{\infty}$, separation $S$ and magnification $r_{mag}$ by taking the example of a supermassive black hole in the strong field limit with the effects of homogeneous plasma. It is concluded that the Van der Waals parameters $a$, $b$ and homogeneous plasma medium have a significant effect on both the shadows and strong gravitational lensing.