Browsing by Author "Bahamonde, Sebastian"

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    Astrophysical flows near f (T) gravity black holes
    (2016) Ahmed, Ayyesha K.; Azreg-Ainou, Mustapha; Bahamonde, Sebastian; Capozziello, Salvatore; Jamil, Mubasher; 27257404
    In this paper, we study the accretion process for fluids flowing near a black hole in the context of f (T) teleparallel gravity. Specifically, by performing a dynamical analysis by a Hamiltonian system, we are able to find the sonic points. After that, we consider different isothermal test fluids in order to study the accretion process when they are falling onto the black hole. We find that these flows can be classified according to the equation of state and the black hole features. Results are compared in f (T) and f (R) gravity.
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    Strong gravitational lensing by a charged Kiselev black hole
    (2017) Azreg, Ainou Mustapha; Bahamonde, Sebastian; Jamil, Mubasher; 0000-0002-3244-7195; R-1759-2019; AAZ-1598-2021
    We study the gravitational lensing scenario where the lens is a spherically symmetric charged black hole (BH) surrounded by quintessence matter. The null geodesic equations in the curved background of the black hole are derived. The resulting trajectory equation is solved analytically via perturbation and series methods for a special choice of parameters, and the distance of the closest approach to black hole is calculated. We also derive the lens equation giving the bending angle of light in the curved background. In the strong field approximation, the solution of the lens equation is also obtained for all values of the quintessence parameter w(q). For all w(q), we show that there are no stable closed null orbits and that corrections to the deflection angle for the Reissner-Nordstrom black hole when the observer and the source are at large, but finite, distances from the lens do not depend on the charge up to the inverse of the distances squared. A part of the present work, analyzed, however, with a different approach, is the extension of Younas et al. (Phys Rev D 92:084042, 2015) where the uncharged case has been treated.