Probing Non-rotating Black Hole in Kalb-Ramond Gravity: Imaging and Polarized Signatures Surrounded by Different Thick Accretion Flows

TL;DR

This paper investigates the shadow and polarization images of a non-rotating black hole in Kalb-Ramond gravity, analyzing how different accretion flow models and parameters affect observable features like brightness, shape, and polarization signatures.

Contribution

It provides the first detailed analysis of black hole shadows and polarized images in Kalb-Ramond gravity with different thick accretion flow models, highlighting the effects of specific parameters on observable features.

Findings

Higher-order image size decreases with increasing $\hat{\lambda}$ or $\\gamma$

Observer inclination $ heta_o$ affects the shape and obscuration of the horizon outline

Polarization intensity is strongest in higher-order image regions and varies with space-time parameters

Abstract

In this work, we consider a spherically symmetric static black hole metric in Kalb-Ramond (KR) gravity, and investigate the impact of relevant parameters on the black hole shadow and polarization images. For black hole shadow images, we consider two geometrically thick accretion disk models such as a phenomenological RIAF-like model and an analytical HOU disk model. In each case, we observe a bright ring-like structure corresponding to the higher-order images with a surrounding region of non-zero intensity that represents the primary image. The increasing values of $\hat{\lambda}$ or $\hat{\gamma}$ results in decrease the size of the higher-order image, while increasing values of observer inclination $\theta_{o}$ alter its shape and cause the horizons outline to be obscured. On the other hand, in HOU disk model, at high observer inclinations, the obscuration of the horizons outline by radiation from outside the equatorial plane is weakened. Consequently, the brightness of the primary image in the phenomenological model is significantly greater than that in the HOU disk model, indicating the strong gravitational lensing effect. For the polarized images, we use only the HOU disk model with anisotropic radiation, assuming an infalling accretion flow matter. The obtained results illustrate that the polarization intensity $P_{o}$ in the higher-order image region is significantly stronger than as compare to other regions, and it is rapidly decreases away from this region. The variation in $\hat{\lambda}$ and $\hat{\gamma}$ depicts the intrinsic structure of the space-time and $\theta_o$ depends on the observers orientation, together they shape the polarization features.