Observational distinction between black holes and naked singularities: the role of the redshift function

Abstract

We suggest that the redshift of photons traveling from past to future null infinity through a collapsing object could provide an observational signature capable of differentiating between the formation of a globally naked singularity and the formation of an event horizon. Supporting evidence for this idea is drawn from the analysis of photons with zero angular momentum through the center of a collapsing spherical dust cloud. We show that the frequency shift as a function of proper time with respect to stationary observers has distinct features depending on whether the object collapses to a black hole or a naked singularity.

6 pages, 3 figures. Journal reference, expanded discussion, typos corrected, updated references

References in corpus (7)

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• Shadow of a naked singularity
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• Cosmic Censorship for Self-Similar Spherical Dust Collapse
• Cauchy horizon stability in a collapsing spherical dust cloud I: geometric optic approximation and spherically symmetric test fields

Cited by in corpus (16)

• Calculating black hole shadows: Review of analytical studies
• Shadows of spherically symmetric black holes and naked singularities
• Can we distinguish black holes from naked singularities by the images of their accretion disks?
• Motion of test particles in the field of a naked singularity
• Shadow of a naked singularity
• Photon sphere and shadow of a time-dependent black hole described by a Vaidya metric
• Global visibility of a strong curvature singularity in nonmarginally bound dust collapse
• Quasi-local photon surfaces in general spherically symmetric spacetimes
• Distinguishing Brans-Dicke-Kerr type naked singularities and black holes with their thin disk electromagnetic radiation properties
• Globally visible singularity in an astrophysical setup
• Generating Rotating Spacetime in Ricci-Based Gravity: Naked Singularity as a Black Hole Mimicker
• Collapsing scenario for the k-essence emergent generalised Vaidya spacetime in the context of massive gravity's rainbow
• The shadow of a collapsing dark star
• Static Vacuum Solutions on Curved Spacetimes with Torsion
• Shadow of higher dimensional collapsing dark star and blackhole
• Cauchy horizon stability in a collapsing spherical dust cloud. II: Energy bounds for test fields and odd-parity gravitational perturbations