Signatures of Lorentz violation in the bright ring for Sgr A* images from radiatively inefficient accretion flows

Abstract We have investigated the effects of Lorentz violation (LV) on the bright ring in Sgr A* images illuminated by the 230 GHz thermal synchrotron emission from radiatively inefficient accretion flows around a rotating LV black hole within the low-energy Hořava gravity framework. Our results reveal that the LV parameter reduces the bright ring diameter yet increases its width, luminosity, azimuthal asymmetry and orientation angle. A higher spin parameter strengthens the LV-induced effects on the bright ring properties. Increasing disk thickness reduces the ring diameter and enhances the LV parameter’s effects on this diameter. The ring width shows no systematic dependence on the disk thickness. These quantities of the bright ring display similar trends against the black hole spin and the LV parameter for the rotating LV black hole. Using EHT observational data of Sgr A*, we find that, at fixed disk thickness, the parameter-space map illustrates that the bounded range of the LV parameter first broadens and then contracts with the growing black hole spin, and shifts toward smaller LV parameter values. In addition, the LV parameter narrows the bounded range of black hole spin: negative LV parameter values shift this range to a higher spin, while positive values shift it to a lower spin. Finally, we probe effects of the LV parameter on the peak position value and the width of the primary image and the $$n=1$$ n = 1 photon ring for the rotating LV black hole. The peak positions and their widths nearly always decrease with the LV parameter. The peak position differences for various LV parameters are more pronounced for a purely Keplerian accretion flow. In addition, the primary image and the $$n=1$$ n = 1 photon ring produced by purely radially free-falling flows are broader than their counterparts generated by purely Keplerian flows.