特低频电磁波吸收与银河系自由电子气分布

Very Low Frequency Electromagnetic Wavse Absorption and Free Electron Gas Distribution in the Milky Way

电磁环境中双黑洞并合可辐射与引力波同频率的电磁信号,但低频电磁波有可能被星系介质吸收。电磁波在穿越大气过程中会被吸收,某些频率的电磁波被吸收得多,某些频率的电磁波被吸收得少,被吸收得少的那些频率窗口被称为电磁波的大气窗口。类似地,电磁波在宇宙空间中传播会被星系介质吸收。着重探讨电磁波在银河系空间中传播的吸收问题。研究发现,电磁波穿越银河系空间到达地球存在下限截止频率。天球上不同方向上对应的下限截止频率不同,存在一个分布,该分布与银河系自由电子气的分布密切相关。该文通过对该截止频率分布进行测定从而确定银河系自由电子气的分布。

Electromagnetic waves will be absorbed when they pass through the atmosphere.Electromagnetic waves with some frequencies are absorbed more,while electromagnetic waves with other frequencies are absorbed less.The frequency range within which the electromagnetic waves are less absorbed is called the atmospheric window of electromagnetic waves.Similarly,the propagation of electromagnetic waves in the universe will be absorbed by the galactic medium.This paper investigates the problem of the absorption of electromagnetic wave when it propagates in the Milky Way.Our analysis shows that there is a lower cut-off frequency for the electromagnetic waves which can reach the earth passing through the Milky Way.Interestingly,the lower cut-off frequency is different respect to different direction on the celestial sphere,which gives a distribution.This distribution is closely related to the distribution of free electron gas in the Milky Way.We propose to determine the distribution of free electron gas in the Milky Way by measuring the cut-off frequency distribution.