We generalize the semiclassical treatment of graviton radiation to gravitational scattering at very large energies $\sqrt{s}\gg m_P$ and finite scattering angles $Θ_s$, so as to approach the collapse regime of impact parameters $b \simeq b_c \sim R\equiv 2G\sqrt{s}$. Our basic tool is the extension of the recently proposed, unified form of radiation to the ACV reduced-action model and to its resummed-eikonal exchange. By superimposing that radiation all-over eikonal scattering, we are able to derive the corresponding (unitary) coherent-state operator. The resulting graviton spectrum, tuned on the gravitational radius $R$, fully agrees with previous calculations for small angles $Θ_s\ll 1$ but, for sizeable angles $Θ_s(b)\leq Θ_c = O(1)$ acquires an exponential cutoff of the large $ωR$ region, due to energy conservation, so as to emit a finite fraction of the total energy. In the approach-to-collapse regime of $b\to b_c^+$ we find a radiation enhancement due to large tidal forces, so that the whole energy is radiated off, with a large multiplicity $\langle N \rangle\sim Gs \gg 1$ and a well-defined frequency cutoff of order $R^{-1}$.
The latter corresponds to the Hawking temperature for a black hole of mass notably smaller than $\sqrt{s}$.
Bifurcated Impact of Neutrino Fast Flavor Conversion on Core-collapse Supernovae Informed by Multi-angle Neutrino Radiation Hydrodynamics
Waseda University（早稻田大学）；National Astronomical Observatory of Japan（日本国立天文台）；Kanto Gakuin University（关东学院大学）；RIKEN（理化学研究所）；National Institute of Technology, Ibaraki College（茨城工业高等专门学校）；Aomori University（青森大学）；High Energy Accelerator Research Organization（高能加速器研究机构）；National Institute of Technology, Numazu College（沼津工业高等专门学校）
Burst particle creation in gravitational collapse to a horizonless compact object
在前一篇论文中[Harada，Cardoso和Miyata，Phys.修订版本\ D { \bf 99}（2019），044039]，它表明，一个中空的透射壳塌缩到一个半径非常接近其视界半径的超紧凑物体通常会发射瞬态霍金辐射，随后是一对彼此相隔很长时间间隔的爆发。在本文中，我们扩展了以前的工作在两个独立的方向：改变边界条件和指定的物质状态方程。首先，我们引入了一个完美的反射表面塌缩到一个超紧凑的对象，并发现这个模型也发出瞬态霍金辐射，其次是一个单一的爆发。其次，我们引入了两种不同的坍缩动力学的超紧物体，并指定相应的物质状态方程。我们发现，瞬态霍金辐射是很常见的早期，而随后的爆发强烈依赖于边界条件和状态方程或制动行为的表面。
