Cherenkov Gravitational Radiation during the Radiation Era

Universe

Yi-Zen Chu¹  Yen-Wei Liu² 

[1] Department of Physics, National Central University, Taoyuan City 32001, Taiwan;Department of Physics, National Tsing-Hua University, Hsinchu 30013, Taiwan;

关键词: gravitational waves;    cosmology;    Cherenkov radiation;   

DOI  :  10.3390/universe7110437

来源: DOAJ

【 摘 要 】

Cherenkov radiation may occur whenever the source is moving faster than the waves it generates. In a radiation dominated universe, with equation-of-state $w=1/3$, we have recently shown that the Bardeen scalar-metric perturbations contribute to the linearized Weyl tensor in such a manner that its wavefront propagates at acoustic speed $\sqrt{w}=1/\sqrt{3}$. In this work, we explicitly compute the shape of the Bardeen Cherenkov cone and wedge generated respectively by a supersonic point mass (approximating a primordial black hole) and a straight Nambu-Goto wire (approximating a cosmic string) moving perpendicular to its length. When the black hole or cosmic string is moving at ultra-relativistic speeds, we also calculate explicitly the sudden surge of scalar-metric induced tidal forces on a pair of test particles due to the passing Cherenkov shock wave. These forces can stretch or compress, depending on the orientation of the masses relative to the shock front’s normal.

【 授权许可】

Unknown