Astrophysical Constraints on Decaying Dark Gravitons

TL;DR

This paper investigates how decaying dark gravitons in a dark dimension scenario affect astrophysical signals, deriving constraints on model parameters and predicting dark matter mass and extra dimension size.

Contribution

It provides the first astrophysical constraints on dark gravitons in a micron-scale extra dimension model, linking decay effects to observable signals.

Findings

Dark matter mass is predicted to be a few hundred keV.

The extra dimension size is constrained to 1-30 micrometers.

Model parameters are consistent with astrophysical bounds.

Abstract

In the dark dimension scenario, which predicts an extra dimension of micron scale, dark gravitons (KK modes) are a natural dark matter candidate. In this paper, we study observable features of this model. In particular, their decay to standard matter fields can distort the CMB and impact other astrophysical signals. Using this we place bounds on the parameters of this model. In particular we find that the natural range of parameters in this scenario is consistent with these constraints and leads to the prediction that the mean mass of the dark matter today is close to a few hundred keV and the effective size of the extra dimension is around $1 - 30 \;\mu\mathrm{m}$.