6/2/2023 0 Comments Era of celestials codes 2020![]() We also notice that the smaller values of the equation of state parameter ωq, for the quintessence, reduces the thermal flux for very small values of the Rastall parameter κλ. We observe that the thermal flux of the accretion disk strongly depends on the intensity of the quintessence in the spacetime of the KNNK black hole in the RG, and the flux decreases for the increasing values of the quintessential intensity. ![]() In our analysis we consider the thin accretion disk model of Novikov and Thorne. Here, we study the effect of strong gravitational field on the light rays emitted from the particles in the accretion disk in the vicinity of the Kerr–Newman–NUT–Kiselev (KNNK) black hole in the Rastall gravity (RG). From the analysis of the reflection features in the X-ray spectrum of the Galactic black hole in EXO 1846-031, we find $-0.1 < q < 0.7$ (90% CL), which is consistent with the hypothesis that the spacetime around the compact object in EXO 1846-031 is a Kerr black hole but does not entirely rule out the $\delta$-Kerr metric. The parameter $\delta=1 q$ quantifies the departure of the source from the Kerr metric and for $q=0$ we recover the Kerr solution. In this work, we consider the $\delta$-Kerr metric, which is an exact solution of the field equations in vacuum and can be obtained from a non-linear superposition of the Kerr metric with a static axially symmetric solution, often referred to as the $\delta$-metric. We can thus speculate on the possibility that the spacetime around astrophysical black holes may be described by other solutions of the Einstein Equations and we can test such a hypothesis with observations. However, even within general relativity, there is not yet a proof that the final product of the complete collapse of an uncharged body can only be a Kerr black hole. The spacetime around astrophysical black holes is thought to be described by the Kerr solution. We discuss our findings in relation to the capability of boson stars to effectively act as black hole mimickers in their optical appearances as well as potential observational discriminators. ![]() ![]() Furthermore, we also find a shadow-like central brightness depression for some of these stars in both axial observations and at the inclination angles above. For accretion disks we find that the latter class of stars actually shows a sequence of additional secondary images in agreement with the hot-spot analysis, a feature absent in typical black hole space-times. For the hot-spots, using inclination angles $\theta=\$ we find a secondary track plunge-through image of photons crossing the interior of the boson star, which can be further decomposed into additional images if the star is compact enough. We consider two families of boson stars supported by quartic and sixth-order self-interaction potentials, and choose three samples of each of them in growing compactness only those with large enough compactness are capable to hold light-rings, namely, null bound orbits. In this work we consider the observational properties of compact boson stars with self-interactions orbited by isotropically emitting (hot-spot) sources and optically thin accretion disks.
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