Black Hole Shadows in M-theory Scenarios

Abstract

We study the shadows of four dimensional black holes in M-theory inspired models. We first inspect the influence of M2-branes on such optical aspects for non-rotating solutions. In particular, we show that the M2-brane number can control the circular shadow size. This geometrical behavior is distorted for rotating solutions exhibiting cardioid shapes in certain moduli space regions. Implementing a rotation parameter, we analyze the geometrical shadow deformations. Among others, we recover the circular behaviors for a large M2-brane number. In addition, we propose a possible connection with observations (from Event Horizon Telescope or future devices) for a particular M-theory compactification by deriving naive constraints on the M2-brane number in the light of the M 87 observational parameters. Investigating the energy emission rate at high energies, we find, in a well-defined approximation, that the associated peak decreases with the M2-brane number.

Superentropic AdS Black Hole Shadows

“…Parallelly to these efforts, optical behaviors have been investigated by considering the deflection angle of lights and the shadow geometry [10][11][12][13][14][15][16]. Concretely, the black hole shadow behaviors have been examined in different theories including M-theory and superstring theory in the presence of D-brane objects [17,18]. The visualization of the shadow cast using the null geodesic equations has been completed by the study of geometrical observables.…”

“…For non-rotating black holes, it has been revealed that the shadow has a circular geometry where its size can be controlled by the mass and other parameters including the charge and dark energy [19]. This geometric manifestation is distorted for ordinary rotating black holes, to exhibit either the D-shape or the cardioid geometries [17,18,20,21]. In addition, it has been shown that the shadow behaviors depend also on other parameters including the brane number and a cosmological scale [18,22].…”

Optical Shadows of Rotating Bardeen AdS Black Holes

“…Moreover, it has been observed that the shadow aspects could depend also on geometric and stringy parameters. Indeed, the brane number and cosmological scale have been implemented where non-trivial geometries have been appeared [34,35]. In this work, we aim to investigate the optical behaviors of Bardeen AdS black holes by examining the corresponding shadows using one dimensional real curves.…”

Superentropic Black Hole Shadows in Arbitrary Dimensions

“…The circular geometric manifestation can be distorted by introducing the rotating parameter which generates nontrivial geometries involving either D or cardioid shapes [14,15,[17][18][19][20]. The latter has been appeared in the study of AdS black holes obtained from type superstrings and Mtheory scenarios using brane physics [19,21]. Certain distorted geometrical behaviors have been observed for rotating stringy solutions exhibiting cardioid shapes by varying the brane number.…”