Observe matter falling into a black hole
It has been well known that in the point of view of a distant observer, all in-falling matter to a black hole (BH) will be eventually stalled and frozen just outside the event horizon of the BH. although an in-falling observer will see the matter falling straight through the event horizon. Thus in this frozen star scenario, as distant observers, we could never observe matter falling into a BH. neither could we see any real BH other than primordial ones, since all other BHs are believed to be formed by matter falling towards singularity. Here we first obtain the exact solution for a pressureless mass shell around a pre—existing BH. The metrics inside and interior to the shell are all different from the Schwarzschild metric of the enclosed mass, meaning that the well-known Birkhoff Theorem can only be applied to the exterior of a spherically symmetric mass. The metric interior to the shell can be transformed to the Schwarzschild metric for a slower clock Which is dependent of the location and mass of the shell; we call this Generalized Birkhoff Theorem. Another result is that there does not exist a singularity nor event horizon in the shell. Therefore the frozen star scenario is incorrect. We also show that for all practical astrophysical settings the in- falling time recorded by an external observer is sufficiently short that future astrophysical instruments may be able to follow the whole process of matter falling into BHs. The distant observer could not distinguish between a real BH and a frozen star, until two such objects merge together. It has been proposed that electromagnetic waves will be produced when two frozen stars merge together, but not true when two real bare BHs merge together. However gravitational waves will be produced in both cases. Thus our solution is testable by future high sensitivity astronomical observations.
General relativity Schwarzschild metric Birkhoff theorem black hole black hole accretion black hole merger frozen star black star
Shuang Nan Zhang Yuan Liu
Physics Department and Center for Astrophysics, Tsinghua University, Beijing 100084, China
国际会议
紧凑型物体的天体物理学国际会议(International Conference on Astrophysics of Compact Objects)
安徽黄山
英文
384-391
2007-07-01（万方平台首次上网日期，不代表论文的发表时间）