Faster rate of Hawking radiation in modified gravity constraining dark matter

TL;DR

This paper investigates how modified gravity theories affect Hawking radiation, revealing that primordial black holes evaporate faster, which constrains their role as dark matter candidates and impacts theories of gravity and dark matter origin.

Contribution

The study demonstrates that in scalar-tensor modified gravity, primordial black holes evaporate faster than in Einstein gravity, providing new constraints on dark matter models.

Findings

Primordial black holes evaporate faster in scalar-tensor gravity.

Black holes of mass ~10^{15} g or less should have evaporated by now.

Constraints on primordial black holes as dark matter candidates are tightened.

Abstract

The exact theory of gravity in the strong field regime is still under debate. There are observations implying the need for modification to Einstein's gravity. On the other hand, the exact constituents of dark matter are also a big puzzle, where primordial black holes (PBHs) are argued to be a potential candidate. We explore Hawking radiation in a modified gravity and find that PBHs evaporate faster in a scalar-tensor theory based modified gravity. Subsequently, all the nonrotating BHs of mass $\sim 10^{15}$ g or less should have been evaporated by today, which is an order of magnitude heavier than what the Einstein gravity predicts. This has many consequences including a strict constraint on contributing PBHs to dark matter, widening the debate of dark matter origin.