Analytic thin disks and rings in a class of nonasymptotically flat static spacetimes

TL;DR

This paper studies how external quadrupolar distortions of static spacetimes influence accretion disk dynamics and emission, revealing observable signatures linked to the spacetime geometry.

Contribution

It demonstrates the impact of external quadrupolar fields on accretion structures and identifies the radial domain where the local spacetime remains self-consistent.

Findings

External quadrupolar distortion affects orbital dynamics and accretion morphology.

The outer radiating region correlates with the transition from radiation to gas pressure dominance.

Distorted spacetime geometries produce observable signatures in accretion flows.

Abstract

External matter distributions can substantially reshape the strong field environment of compact objects, yet this effect is usually neglected in idealized isolated models. In this work, we investigate geometrically thin, optically thick relativistic accretion onto a static axisymmetric space-time that describes a slightly deformed compact object immersed in an external quadrupolar field as an exact solution of vacuum Einstein field equations. Our aim is to determine whether such locally geometries can produce distinctive accretion signatures and, more broadly, to identify the physically meaningful radial domain over which the local solution remains self-consistent. We show that the external quadrupolar distortion leaves a clear imprint on both orbital dynamics and accretion structure. We further find that the outer edge of the radiating region is closely tied to the transition between radiation pressure and gas pressure dominance, which may link the geometry to the thermodynamic properties of the flow. Therefore, the local nature of the distorted spacetime is not merely a formal geometric feature, but has observable consequences for the morphology and emission properties of accretion flows.