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    Circular geodesic of Bardeen and Ayon-Beato-Garcia regular black-hole and no-horizon spacetimes

    Zdeněk Stuchlík · Prosinec 01, 2015 · Fyzika · 0 comments
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    Publication date: Dec 2015

    Abstract:
    In this paper, we study circular geodesic motion of test particles and
    photons in the Bardeen and Ayon-Beato-Garcia (ABG) geometry describing
    spherically symmetric regular black-hole or no-horizon spacetimes. While
    the Bardeen geometry is not exact solution of Einstein’s equations, the
    ABG spacetime is related to self-gravitating charged sources governed by
    Einstein’s gravity and nonlinear electrodynamics. They both are
    characterized by the mass parameter m and the charge parameter g. We
    demonstrate that in similarity to the Reissner-Nordstrom (RN) naked
    singularity spacetimes an antigravity static sphere should exist in all
    the no-horizon Bardeen and ABG solutions that can be surrounded by a
    Keplerian accretion disc. However, contrary to the RN naked singularity
    spacetimes, the ABG no-horizon spacetimes with parameter g/m > 2 can
    contain also an additional inner Keplerian disc hidden under the static
    antigravity sphere. Properties of the geodesic structure are reflected
    by simple observationally relevant optical phenomena. We give silhouette
    of the regular black-hole and no-horizon spacetimes, and profiled
    spectral lines generated by Keplerian rings radiating at a fixed
    frequency and located in strong gravity region at or nearby the
    marginally stable circular geodesics. We demonstrate that the profiled
    spectral lines related to the regular black-holes are qualitatively
    similar to those of the Schwarzschild black-holes, giving only small
    quantitative differences. On the other hand, the regular no-horizon
    spacetimes give clear qualitative signatures of their presence while
    compared to the Schwarschild spacetimes. Moreover, it is possible to
    distinguish the Bardeen and ABG no-horizon spacetimes, if the
    inclination angle to the observer is known.

    Authors:
    Stuchlík, Zdeněk; Schee, Jan;

    https://ui.adsabs.harvard.edu/abs/2015IJMPD..2450020S

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