Probing Observable Features of Lorentz violation in Low-Energy Hořava Gravity with Accretion Disk Images of Black Hole

TL;DR

This work investigates observable signatures of Lorentz violation in low-energy Hořava gravity by simulating thin-disk black hole images and polarization using backward ray-tracing in a ZAMO framework. The rotating LV black hole is parameterized by $\ell$, with Kerr recovered at $\ell=0$, and the study analyzes how $\ell$ alters the inner shadow, critical curve, and polarization patterns relative to Kerr. Key findings show that positive $\ell$ amplifies the ring brightness and spins effects, producing distinctive leftward D-shaped curves and enhanced angular velocity near the horizon, while negative $\ell$ tends to circularize the shadow and suppress drag, with polarization patterns also exhibiting LV-dependent changes. The results suggest that high-resolution EHT-like observations combining thin-disk images and polarization could test LV effects and constrain $\ell$, potentially validating or challenging the low-energy Hořava gravity framework.

Abstract

In this paper, we study the observable signatures of Lorentz violation (LV) in low-energy Horava gravity by simulating the images and polarization features of rotating LV black holes using a backward ray-tracing method. Within a thin-disk accretion model and the ZAMO framework, we numerically solve the geodesics equation of photon and simulate the corresponding thin-disk images and polarization patterns. The results show that the LV parameter l strongly affects the inner shadow, brightness asymmetry, and polarization properties of the thin disk. The decrease of l leads to a more elliptical and untilted inner shadow, while increasing l produces a pronounced leftward D-shaped structure of the critical curve. In addition, the variation of l alters the distribution of polarized intensity and polarization direction, especially near the critical curve. Moreover, it also shows that a positive l enhances the black hole's angular velocity, while a negative one suppresses it, indicating that the sign of l determines the trend direction of the LV effect. These findings suggest that future high-resolution EHT observations combining the thin-disk images and polarization patterns could provide valuable tests of the LV effect.

Figures (11)

• Figure 1: The method of stereographic projection
• Figure 2: Images of the rotating LV black hole illuminated by the thin disk in Hořava gravity.
• Figure 3: The redshift of direct images of the thin disk, where the red and blue color represent red shift and blue shift respectively.
• Figure 4: The redshift of lensed images of the thin disk.
• Figure 5: The intensity distribution of the screen along the $x$-axis and the $y$-axis. For the first two graphs, $a=0.1$(blue line) and $a=0.94$(black line), while for the last two graphs, $\ell=0.99$(blue line) and $\ell=-0.99$(black line).