Shadows and thin accretion disk images of the $\gamma$-metric

Abstract

The $\gamma$-metric is a static, axially-symmetric singular solution of the vacuum Einstein's equations without an event horizon. This is a two-parameter family of solutions, generic values of one of which (called $\gamma$) measure the deviation from spherical symmetry. Here, we first study the shadow cast by this geometry, in order to constrain the $\gamma$-metric from observations. We find that for $\gamma <1/2$, there are, in principle, no shadows cast. On the other hand, shadows cast for all values of $\gamma \ge 1/2$ are consistent with observations of M$87^{\ast }$ by the Event Horizon Telescope. We also study images of thin accretion disks in the $\gamma$-metric background. In situations where the $\gamma$-metric possesses light rings, these qualitatively mimic Schwarzschild black holes with the same ADM mass, while in the absence of such rings, they are drastically different from the black hole case.

arXiv comment14 pages, 22 figures

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• Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A${}^{\ast }$
• Shadow and deflection angle of asymptotic, magnetically-charged, non-singular black hole
• Null geodesics and shadow of 4$D$ Einstein-Gauss-Bonnet black holes surrounded by quintessence
• Thin accretion disk images of the black hole in symmergent gravity
• Motion of particles around a magnetically charged Euler-Heisenberg black hole with scalar hair and the Event Horizon Telescope
• Constraining deviations from spherical symmetry using $\gamma$-metric
• Modelling the Sgr A${}^{\ast }$ and M87${}^{\ast }$ shadows by using the Kerr-Taub-NUT metrics in the presence of a scalar field
• Periodic orbits and their gravitational wave radiations in $\gamma$-metric
• Asymptotically-Flat Black Hole Solutions in Symmergent Gravity
• Shadow of rotating black holes with consistent thermodynamics
• Quasinormal spectra of a wormhole family: overtone features and a parameter-controlled redshift