Observational appearances of magnetically charged black holes in Born–Infeld electrodynamics

Abstract

In this paper, we investigate the observational appearances of magnetically charged black holes in Born–Infeld (BI) electrodynamics. We examine the effects of the magnetic charge and the BI parameter on the geodesics with different impact parameters. Using the backward ray tracing method, we investigate how spherically symmetric accretions interact with black hole shadows and photon spheres. The shadows of infalling accretion are darker than that of static ones. Moreover, the radius of the photon sphere is an intrinsic property of the spacetime independent of accretions. We then study how the thin disk models affect the black hole shadows. After obtaining the transfer functions, we divide photons emitted from the thin disk into three categories: direct emission, lens ring, and photon ring. Applying three emission models, we find that the width of the shadow is dominated by the direct emission, the photon ring and the lens ring can hardly be identified by changing the emission models.

Observational appearances of hairy black holes in the framework of gravitational decoupling

“…The visible shapes of the brightest black holes accompanied by an accretion disk were comparable with the EHT observations for M87 * and SgrA * [17,18]. In recent years, research on black hole shadows has extended to black holes in Born-Infeld electromagnetic fields [19,20], the Ayón-Beato-García black hole family [21] and black holes with multiple photon spheres [22][23][24][25]. Moreover, Euler-Heisenberg black holes [26], black holes immersed in quintessence dark energy [27], brane-world black holes [28] and others have also been studied [29][30][31][32][33].…”

“…The specific intensity I with respect to the impact parameter b can be obtained by substituting equation (16) and equation (19) into equation (18). We set γ = 1 and M = 1 for simplicity.…”

“…In this subsection, we will consider four emission models to work out the optical appearances of a hairy black hole in WEC. One can focus on four different emission positions of the accretion disk: ISCO, the photon sphere radius r ph , the event horizon r h [19] and a certain position r = 17/3 outside the ISCO [55]. The first three positions are special and have applications in many articles studying black hole shadows.…”

Lyapunov exponents and phase transitions of Born-Infeld AdS black holes

“…The BI AdS black hole solution in the presence of a cosmological constant was studied in [46,47]. The thermodynamic behaviors and phase transitions of BI black holes in different fields have also been investigated [48][49][50][51][52].…”