Astrophysical Observations of a Dark Matter-Baryon Fifth Force

TL;DR

This paper investigates a long-range fifth force between dark matter and baryons, showing it can significantly affect neutron star heating and pulsar timing, and derives new constraints from astrophysical observations.

Contribution

It introduces the first constraints on a long-range dark matter-baryon fifth force using neutron star heating and pulsar timing data, extending the parameter space of dark matter interactions.

Findings

Fifth force strength can be comparable to gravity at large ranges.

Neutron star heating and pulsar timing are sensitive probes of such fifth forces.

Combined astrophysical limits can surpass collider and laboratory constraints.

Abstract

We consider the effects of an attractive, long-range Yukawa interaction between baryons and dark matter (DM), focusing in particular on temperature and pulsar timing observations of neutron stars (NSs). We show that such a fifth force, with strength modestly stronger than gravity at ranges greater than tens of kilometers (corresponding to mediator masses less than $10^{-11} \text{eV}$), can dramatically enhance dark matter kinetic heating, capture, and pulsar timing Doppler shifts relative to gravity plus short range interactions alone. Using the coldest observed NS and pulsar timing array (PTA) data, we derive limits on fifth force strength over a DM mass range spanning light dark matter up to order solar mass composite DM objects. We also consider an indirect limit by combining bullet cluster limits on the DM self-interaction with weak equivalence principle test limits on baryonic self-interactions. We find the combined indirect limits are moderately stronger than kinetic heating and PTA limits, except when considering a DM subcomponent.