Vector Fuzzy Dark Matter, Fifth Forces, and Binary Pulsars

TL;DR

This paper investigates how an oscillating ultralight vector dark matter field influences binary pulsar dynamics, revealing potential observable effects and constraints comparable to laboratory tests of fundamental forces.

Contribution

It introduces a detailed analysis of vector fuzzy dark matter effects on binary systems, highlighting differences from scalar fields and exploring direct coupling implications.

Findings

Secular effects could be observable in pulsar timing if dark matter density is high.

Constraints from pulsar data are competitive with laboratory equivalence principle tests.

Vector dark matter can mediate baryonic forces, affecting binary system dynamics.

Abstract

We study the secular effects that an oscillating background ultralight (fuzzy) cosmological vector field has on the dynamics of binary systems; such effects appear when the field and the binary are in resonance. We first consider the gravitational interaction between the field and the systems, and quantify the main differences with an oscillating background scalar field. If the energy density of such a field is sufficiently large, as required if it is supposed to be all of the dark matter, we show that the secular effects could yield potentially observable signatures in high precision time of arrival measurements of binary pulsars. We then analyse the secular effects that arise when the field is directly coupled to the bodies in the binary. We show that this study is particularly relevant for models where fuzzy dark matter mediates a baryonic force $B$ (or $B-L$, with $L$ the lepton number), due to the stellar amount of nucleons present in the stars. The constraints we obtain from current data are already competitive with (or even more constraining than) laboratory tests of the equivalence principle.