Abstract
We study optical effects in quintessential Kerr black hole spacetimes corresponding to the limiting case of the equation-of-state parameter $\omega_{q}=-1/3$ of the quintessence. In dependence on the dimensionless quintessential field parameter $c$, we determine the black hole silhouette and the spectral line profiles of Keplerian disks generated in this special quintessential Kerr geometry, representing an extension of the general modifications of the Kerr geometry introduced recently by Ghasemi-Nodehi and Bambi \cite{Gha-Bam:2016:EPJC:}. We demonstrate that due to the influence of the parameter $c$, the silhouette is almost homogeneously enlarged, and the spectral line profiles are redshifted with almost conserved shape.
Highlights
Recent research of astrophysical and connected optical phenomena related to possible direct observations of effects occurring in the field of black holes and naked singularities, or other strong gravity compact objects, is often concentrated in effects occurring in the modified Kerr geometry implied by alternatives to the Einstein gravity
We study optical effects in quintessential Kerr black hole spacetimes corresponding to the limiting case of the equation-of-state parameter ωq = −1/3 of the quintessence
Studies of the astrophysical phenomena in the field of black holes, based on the modified geometry only, can give very important basic information, but they have to be considered very carefully, as additional effects related to the origin of the modified gravity, or the source terms hidden behind the dirty Kerr geometry, could significantly alter the predictions based on the purely geometrical considerations
Summary
Recent research of astrophysical and connected optical phenomena related to possible direct observations of effects occurring in the field of black holes and naked singularities, or other strong gravity compact objects, is often concentrated in effects occurring in the modified Kerr geometry implied by alternatives to the Einstein gravity. Ghasemi-Nodehi and Bambi proposed a new version of modified Kerr geometry, where the latitudinal profiles of the metric coefficients can be modified [15] In this approach, the geometry modifications are related to all terms of the Kerr metric containing mass M and specific angular momentum (spin) a. We study the black hole silhouette shape, and the profile of the spectral lines of radiation from the inner parts of the Keplerian disks for the special limit (ωq = −1/3) of the quintessential Kerr metric, in dependence on the parameter c. Both these phenomena are fully governed by the geodesic structure of the quintessential Kerr spacetime.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
