Rotating wormhole shadows develop cusps above a universal critical redshift value λ_c, yielding four morphologies: smooth, cuspy, ears touching, and throat drowning.
Gravastar Shadows
3 Pith papers cite this work. Polarity classification is still indexing.
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abstract
Direct observation of black holes is one of the grand challenges in astronomy. If there are super-compact objects which possess unstable circular orbits of photons, however, it may be difficult to distinguish them from black holes by observing photons. As a model of super-compact objects, we consider a gravastar (gravitational-vacuum-star) which was originally proposed by Mazur and Mottola. For definiteness, we adopt a spherical thin-shell model of a gravastar developed by Visser and Wiltshire, which connects interior de-Sitter geometry and exterior Schwarzschild geometry. We find that unstable circular orbits of photons can appear around the gravastar. Then, we investigate the optical images of the gravastar possessing unstable circular orbits, with assuming the optically transparent surface of it and two types of optical sources behind the gravastar: (i) an infinite optical plane and (ii) a companion star. The main feature of the image of (i) is that a bright disk and a dark thick ring surrounding the disk appear in the center of the region which would be completely dark if the compact object was not the gravastar but Schwarzschild black hole. Also in the case (ii), a small disk and arcs around the disk appear in the region which would be completely dark for the lensing image by Schwarzschild black hole. Because characteristic images appear inside the gravastar in both cases, we could tell the difference between a black hole and a gravastar with high-resolution VLBI observations near future.
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Bayesian fitting to mock GRAVITY data shows robust detection of secondary images from Sgr A* flares requires both an order-of-magnitude larger sample and astrometric uncertainties reduced to 40% of current levels for |ΔBIC| > 7.9.
Current and future observations can test whether dark compact objects are Kerr black holes or exotic alternatives, with null results strengthening the black hole paradigm.
citing papers explorer
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On the Cuspy Structure of Rotating Wormhole Shadows
Rotating wormhole shadows develop cusps above a universal critical redshift value λ_c, yielding four morphologies: smooth, cuspy, ears touching, and throat drowning.
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Detectability of secondary images from flares near Sgr A* with mock GRAVITY data
Bayesian fitting to mock GRAVITY data shows robust detection of secondary images from Sgr A* flares requires both an order-of-magnitude larger sample and astrometric uncertainties reduced to 40% of current levels for |ΔBIC| > 7.9.
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Testing the nature of dark compact objects: a status report
Current and future observations can test whether dark compact objects are Kerr black holes or exotic alternatives, with null results strengthening the black hole paradigm.