Big Rip: heating by Hawking radiation and a possible connection to conformal cyclic cosmology

TL;DR

This paper explores the Big Rip scenario, showing Hawking radiation diverges at the singularity and proposing a novel conformal cyclic cosmology model where the future spacetime becomes conformally invariant at the Big Rip, avoiding mass decay.

Contribution

It introduces a new variant of Penrose's conformal cyclic cosmology where the Big Rip replaces the remote future, linking Hawking radiation divergence to cosmological cyclicity.

Findings

Hawking radiation diverges at the Big Rip

The proposed model removes the need for mass decay

Conformal invariance is achieved at the Big Rip

Abstract

In the Big Rip cosmological scenario, a FRW universe containing dark energy with $w < -1$ in its equation of state (phantom energy) expands in such way that, in a finite time span, the scale factor diverges to infinity and the size of the cosmic horizon goes to zero. Here we revisit this scenario in light of the fact that Hawking radiation is expected to be generated at the apparent horizon of a FRW universe, and show that the energy density and temperature of that radiation both diverge at the Big Rip. We then use this fact to propose a new variant of Penrose's conformal cyclic cosmology model in which the future spacetime metric becomes conformally invariant at the Big Rip instead of in the remote future of a de Sitter universe; this removes the need for mass decay from the model and makes it consistent with current physical laws.