Light escape cones in the locally non-rotating reference frames of the Kerr-de Sitter superspinars and related superspinar shadows

TL;DR

This paper analyzes the escape cones and shadows of Kerr-de Sitter superspinars in locally non-rotating frames, considering various spacetime parameters, and explores their observational implications near static observers.

Contribution

It introduces a comprehensive method to construct local escape cones and superspinar shadows in Kerr-de Sitter spacetimes for all classes of naked singularities and observer positions.

Findings

Constructed escape cones for all KdS naked singularity classes

Analyzed superspinar shadows near static observers close to the static radius

Identified parameter ranges for observable superspinar shadows

Abstract

The construction of local escape cones and their complementary cones, related to the locally non-rotating frames (LNRFs) orbiting superspinars with the external field described by the Kerr-de Sitter (KdS) naked singularity (NS) spacetimes, is described for all possible classes of the KdS NS spacetimes and all possible positions of the photon emitter. The notion of the local escape cones is then applied to construct the shadow of the KdS superspinars related to the distant static observers represented by the LNRFs located near the so-called static radius where the spacetime is close to the asymptotically flat region of the Kerr spacetimes. The shadow construction is focused on the KdS superpsinars limited by the cosmological and astrophysical restrictions on the spacetime parameters, namely the superspinar dimensionless spin and the dimensionless cosmological parameter relating the cosmological constant and the superspinar's mass.