Shadows of Kerr black holes with a Gaussian-distributed plasma in the polar direction

Zhang, Zhenyu; Yan, Haopeng; Guo, Minyong; Chen, Bin

doi:10.1103/physrevd.107.024027

Cited by 20 publications

(5 citation statements)

References 34 publications

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“…Recently, various BH solutions have been considered to investigate their shadows in the presence of plasma, see refs. [72][73][74][75][76][77][78]. In [76], Briozzo et al considered Konoplya, Stuchlík and Zhidenko class of BHs to study the aberration effects in plasma medium.…”

Section: Jcap05(2024)047mentioning

confidence: 99%

Influence of plasma on the optical appearance of spinning black hole in Kalb-Ramond gravity and its Existence around M87* and Sgr A*

Raza,

Zubair,

Maqsood

2024

J. Cosmol. Astropart. Phys.

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The visible universe is filled with different types of plasma media in the form of stars, nebulas and other forms of excited gases. These matter fields have a high influence on the gravity and are likely to be present around the black holes due to the immense gravitational attraction. Since a plasma medium affects the speed of light, therefore we investigated the null geodesics and various optical features around the rotating black hole in Kalb-Ramond gravity immersed in plasma medium. Various plasma distributions are considered to develop a comparative study for their influence on unstable null circular orbits, shadows and evaporation rate of the black hole in the presence of a plasma medium. Moreover, the shadow results are also compared with Event Horizon Telescope data for M78* and Sgr A* in order to estimate the parametric bounds for which the rotating black hole in Kalb-Ramond gravity is considered either M87* or Sgr A* under the different values of plasma parameters. From this analysis, we also found the distribution of plasma that has a significant impact on the above mentioned features and is most likely to be present around M87* and Sgr A*.

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Section: Jcap05(2024)047mentioning

confidence: 99%

Influence of plasma on the optical appearance of spinning black hole in Kalb-Ramond gravity and its Existence around M87* and Sgr A*

Raza,

Zubair,

Maqsood

2024

J. Cosmol. Astropart. Phys.

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“…In this subsection, we would like to give a quantitative study of the variation of the shadow concerning the radius of the surface of a CO. Following the work [57,58], we use the average radius R as the characteristic length of a shadow.…”

Section: Quantitative Study Of the Variation Of The Co Shadowmentioning

confidence: 99%

How different of shadows of compact objects with and without horizons?

Wang¹,

Hou²,

Guo³

2023

Preprint

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In this work, we theoretically assume that a compact object (CO) can have a dark surface so that the CO is simplified to have no emissions and reflections. Considering that the radius of the surface can be located inside or outside the photon region, which is closely related to the shadow curve, we investigate if a CO without an event horizon could produce shadow structures similar to black holes and figure out how different of shadows of COs with and without horizons. In particular, by introducing the (possible) observational photon region, we analytically construct an exact correspondence between the shadow curves with the impact parameters of photons and find that there are indeed several differences for shadows of COs without horizons and black holes. More precisely, We found the shadow curve is still determined by the photon region when the radius of the surface is small enough to retain a whole photon region outside the shell. When only part of the photon region remains, the shadow curve is partially determined by the photon region, and the remaining portion of the shadow curve is partly controlled by the impact parameters of photons which has a turning point on the surface. When there's no photon region outside the surface, the shadow curve is totally controlled by the impact parameters of photons which has a turning point on the surface.

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“…It is also noteworthy that, in both static and infalling accretion, the impact parameter corresponding to the peak of the specific intensity is always the same. This is because, in this paper, we ignore the other factors that may affect the photons' equivalent metric, such as the electromagnetic interaction between the accretion matters and photons [96].…”

Section: Infalling Spherical Accretionsmentioning

confidence: 99%

Observational appearances of magnetically charged black holes in Born–Infeld electrodynamics

2023

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In this paper, we investigate the observational appearances of magnetically charged black holes in Born–Infeld (BI) electrodynamics. We examine the effects of the magnetic charge and the BI parameter on the geodesics with different impact parameters. Using the backward ray tracing method, we investigate how spherically symmetric accretions interact with black hole shadows and photon spheres. The shadows of infalling accretion are darker than that of static ones. Moreover, the radius of the photon sphere is an intrinsic property of the spacetime independent of accretions. We then study how the thin disk models affect the black hole shadows. After obtaining the transfer functions, we divide photons emitted from the thin disk into three categories: direct emission, lens ring, and photon ring. Applying three emission models, we find that the width of the shadow is dominated by the direct emission, the photon ring and the lens ring can hardly be identified by changing the emission models.

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Shadows of Kerr black holes with a Gaussian-distributed plasma in the polar direction

Cited by 20 publications

References 34 publications

Influence of plasma on the optical appearance of spinning black hole in Kalb-Ramond gravity and its Existence around M87* and Sgr A*

Influence of plasma on the optical appearance of spinning black hole in Kalb-Ramond gravity and its Existence around M87* and Sgr A*

How different of shadows of compact objects with and without horizons?

Observational appearances of magnetically charged black holes in Born–Infeld electrodynamics

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