English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We study gravitational lensing in strong-field limit by a static sphericallysymmetric black hole in quartic scalar field Horndeski gravity havingadditional hair parameter $q$, evading the no-hair theorem. We find an increasein the deflection angle $\alpha_D$, photon sphere radius $x_{ps}$, and angularposition $\theta_{\infty}$ that increases more quickly while angular separation$s$ more slowly, but the ratio of the flux of the first image to all otherimages $r_{mag}$ decreases rapidly with increasing magnitude of the hair $q$.We also discuss the astrophysical consequences in the supermassive black holesat the centre of several galaxies and note that the black holes in Horndeskigravity can be quantitatively distinguished from the Schwarzschild black hole.Notably, we find that the deviation $\Delta\theta_{\infty}$ of black holes inHorndeski gravity from their general relativity (GR) counterpart, forsupermassive black holes Sgr A* and M87, for $q=-1$ respectively, can reach asmuch as $25.192~\mu$as and $18.92~\mu$as while $\Delta s$ is about$1.121~\mu$as for Sgr A* and $0.8424~\mu$as for M87*. The ratio of the flux ofthe first image to all other images suggest that the Schwarzschild images arebrighter than those of the black holes in Horndeski gravity, wherein thedeviation $|\Delta r_{mag}|$ is as much as 3.082. The results suggest thatobservational tests of hairy black holes in Horndeski gravity are indeedfeasible.

Investigating strong gravitational lensing effects by suppermassive black holes with Horndeski gravity