https://doi.org/10.1140/epjc/s10052-022-10782-3
Regular Article - Theoretical Physics
Shadow and quasinormal modes of the Kerr–Newman–Kiselev–Letelier black hole
1
Inha University in Tashkent, Ziyolilar 9, 100170, Tashkent, Uzbekistan
2
Akfa University, Milliy Bog’ Street 264, 111221, Tashkent, Uzbekistan
3
National University of Uzbekistan, 100174, Tashkent, Uzbekistan
4
Tashkent State Technical University, 100095, Tashkent, Uzbekistan
5
School of Electrical Engineering and Computer Science, National University of Sciences and Technology, H-12, Islamabad, Pakistan
6
Department of Physics, Zhejiang Normal University, 321004, Jinhua, China
7
Physics Department, State University of Tetovo, Ilinden Street nn, 1200, Tetovo, North Macedonia
b
ibrar.hussain@seecs.nust.edu.pk
Received:
25
July
2022
Accepted:
3
September
2022
Published online:
21
September
2022
We investigate the null geodesics and the shadow cast by the Kerr–Newman–Kiselev–Letelier (KNKL) black hole for the equation of state parameter 
and for different values of the spacetime parameters, including the quintessence parameter 
, the cloud of string (CS) parameter b, the spin parameter a and the charge Q of the black hole. We notice that for the increasing values of the parameters and b the size of the shadow of the KNKL black hole increases and consequently the strength of the gravitational field of the black hole increases. On the other hand with increase in the charge Q of the black hole the size of the shadow of the black hole decreases. Further with the increase in the values of the spin parameter a of the KNKL black hole, we see that the distortion of the shadow of the black hole becomes more prominent. Moreover we use the data released by the Event Horizon Telescope (EHT) collaboration, to restrict the parameters b and for the KNKL black hole, using the shadow cast by the KNKL black hole. To this end, we also explore the relation between the typical shadow radius and the equatorial and polar quasinormal mods (QNMs) for the KNKL black hole and extend this correspondence to non-asymptotically flat spacetimes. We also study the emission energy rate from the KNKL black hole for the various spacetime parameters, and observe that it increases for the increasing values of both the parameters and b for fixed charge-to-mass and spin-to-mass ratios of the KNKL black hole. Finally, we investigate the effects of plasma on the photon motion, size and shape of the shadow cast by the KNKL black hole. While keeping the spacetime parameters fixed, we notice that with increase in the strength of the plasma medium the size of the shadow of the KNKL black hole decreases and therefore the intensity of the gravitational field of the KNKL black hole decreases in the presence of plasma.
© The Author(s) 2022
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3. SCOAP3 supports the goals of the International Year of Basic Sciences for Sustainable Development.
