Radiation enhancement and "temperature" in the collapse regime of gravitational scattering

Abstract

We generalize the semiclassical treatment of graviton radiation to gravitational scattering at very large energies $\sqrt{s}\gg m_P$ and finite scattering angles ${\Theta }_s$, 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 ${\Theta }_s\ll 1$ but, for sizeable angles ${\Theta }_s(b)\le {\Theta }_c=O(1)$ acquires an exponential cutoff of the large $\omega R$ 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 $⟨N⟩\sim Gs\gg 1$ 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 $\sqrt{s}$.

35 pages, 18 figures

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Cited by in corpus (5)

• Infrared features of gravitational scattering and radiation in the eikonal approach
• Soft gravitational radiation from ultra-relativistic collisions at sub- and sub-sub-leading order
• Wave scattering event shapes at high energies
• Unitarity restoring graviton radiation in the collapse regime of scattering
• Soft gravitational radiation from multi-body collisions