Astrophysical Bounds on Global Strings

TL;DR

This paper investigates how global strings, as topological defects, influence astrophysical systems gravitationally and uses observations to set bounds on their abundance in the universe.

Contribution

It provides new constraints on the cosmic abundance of global strings by analyzing their gravitational effects on astrophysical systems.

Findings

Global strings can be constrained by their gravitational influence.

Observed tidal disruptions limit the number of global strings.

Bounds on global string abundance are tighter than previous estimates.

Abstract

Global topological defects produce nonzero stress-energy throughout spacetime, and as a result can have observable gravitational influence on surrounding matter. Gravitational effects of global strings are used to place bounds on their cosmic abundance. The minimum separation between global strings is estimated by considering the defects' contribution to the cosmological energy density. More rigorous constraints on the abundance of global strings are constructed by examining the tidal forces such defects will have on observable astrophysical systems. The small number of observed tidally disrupted systems indicates there can be very few of these objects in the observable universe.