The Dark Dimension, the Swampland, and the Dark Matter Fraction Composed of Primordial Near-Extremal Black Holes

Understand

In a recent publication we studied the decay rate of primordial black holes perceiving the dark dimension, an innovative five-dimensional (5D) scenario that has a compact space with characteristic length-scale in the micron range.

• We demonstrated that the rate of Hawking radiation of 5D black holes slows down compared to 4D black holes of the same mass.
• Armed with our findings we showed that for a species scale of ${\cal O} (10^{9}~{\rm GeV})$, an all-dark-matter interpretation in terms of primordial black holes should be feasible for black hole masses in the range $10^{14} \lesssim M/{\rm g} \lesssim 10^{21}$.
• As a natural outgrowth of our recent study, herein we calculate the Hawking evaporation of near-extremal 5D black holes.