标题： 强透镜系统中等离子体引起的时滞 显示英文标题

标题： Time delay induced by plasma in strong lens systems

摘要： 如果引力透镜被非均匀等离子体包围，除了真空中的引力偏折外，还会发生色散折射。 此外，信号传播速度相比真空会降低。 在本文中，我们分析研究了等离子体中引力透像情况下的时间延迟，重点放在强透镜系统上。 我们考虑以下贡献：在引力和等离子体共同作用下，由于轨迹弯曲引起的几何延迟；光线在透镜引力场中的势延迟；由于光速在介质中降低而在等离子体中产生的色散延迟。 我们采用奇异等温球作为引力透镜的模型，并考虑周围等离子体任意球对称分布。 对于这种情况，找到了两个图像之间时间延迟的等离子体修正的紧凑解析形式，便于估算。 我们还讨论了等离子体对从强透镜系统时间延迟观测中确定的哈勃常数值的可能影响。 显示英文摘要

摘要： If the gravitational lens is surrounded by non-homoheneous plasma, in addition to the vacuum gravitational deflection, chromatic refraction occurs. Also, the speed of signal propagation decreases compared to vacuum. In this article, we investigate analytically the time delay in the case of gravitational lensing in plasma, focusing on strong lens systems. We take into account the following contributions: geometric delay due to trajectory bending in the presence of both gravity and plasma; potential delay of the ray in the gravitational field of the lens; dispersion delay in the plasma due to decrease of speed of light signal in the medium. We consider singular isothermal sphere as a model of gravitational lens, and arbitrary spherically symmetric distribution of surrounding plasma. For this scenario, plasma corrections for the time delay between two images are found in compact analytical form convenient for estimates. We discuss also the possible influence of the plasma on the value of the Hubble constant, determined from observations of the time delay in strong lens systems.