We consider the observational effects of a deficit angle, w, in the topology of the solar system and in the 'double pulsar' system PSR J0737-3039A/B. Using observations of the perihelion precession of Mercury, and the gravitational deflection of light due to the Sun, we constrain the magnitude of such a deficit angle in the solar system to be 2*pi*(1-w), with 0<(1-w)<10^(-9) at 95% confidence. We calculate the effects of a deficit angle on the periastron advance, geodetic precession rate and inclination angle of the double pulsar system and use the observational data to obtain the constraint 0<(1-w)<2.4*10^(-8) at 95% confidence. Although this result is weaker than the solar system bound, it is in a very different physical environment, where accumulating data is likely to lead to tighter constraints in the future.
Observational evidence for the formation of trapping horizons in astrophysical black holes
在广义相对论中，黑洞的特征是它们的捕获视界，一种只能向内穿过的单向膜。在天体物理学上，黑洞中的俘获视界的存在可以用反证法（reductio ad absurdum argument）在观测上进行检验，用具有物理表面的无视界结构代替黑洞，并寻找与电磁波和引力波观测不一致的地方。在这种方法中，无水平线物体的半径总是大于但任意接近相同质量的黑洞的视界所在的位置。这些替代方案的半径上限已提供使用电磁观测（在光学/红外波段）的天文源在星系中心，但缺乏下限，留下不受约束的巨大区域的参数空间。我们在这里表明，下限的半径不发展捕获地平线的地平线上的物体，可以放置使用观测吸积系统。这个结果与模型无关，只依赖于由无视界物体周围的时空几何所决定的局部因果关系概念。这些观测范围大大减少了以前允许的参数空间，提高了利用电磁观测建立陷阱视界存在的前景。
Astrophysical Black holes: An Explanation for the Galaxy Quenching
Ahmedabad University（艾哈迈达巴德大学）；UM-DAE Centre for Excellence in Basic Sciences (CEBS)（基础科学卓越中心（CEBS））；Max Planck Institute for Radio Astronomy（马克斯·普朗克射电天文研究所）；University of Alabama（阿拉巴马大学）
