Influence of quintessence dark energy on the shadow of black hole

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Regular Article - Theoretical Physics

Influence of quintessence dark energy on the shadow of black hole Xiao-Xiong Zeng1,2,a , Hai-Qing Zhang4,3,b 1

State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing 400074, China Department of Mechanics, Chongqing Jiaotong University, Chongqing 400074, China 3 Department of Space Science, Center for Gravitational Physics, Beihang University, Beijing 100191, China 4 International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191, China

2

Received: 20 August 2020 / Accepted: 9 November 2020 © The Author(s) 2020

Abstract We investigate the effects of quintessence dark energy on the shadows of black hole, surrounded by various profiles of accretions. For the thin-disk accretion, the images of the black hole comprises the dark region and bright region, including direct emission, lensing rings and photon rings. Although their details depend on the form of the emission, generically, direct emission plays a major role for the observed brightness of the black hole, while the lensing ring makes a small contribution and the photon ring makes a negligible contribution. The existence of a cosmological horizon also plays an important role in the shadows, since the observer in the domain of outer communications is near the cosmological horizon. For spherically symmetric accretion, static and infalling matters are considered. We find that the positions of photon spheres are the same for both static and infalling accretions. However, the observed specific intensity of the image for infalling accretion is darker than for static accretion, due to the Doppler effect of the infalling motion.

Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . 2 Light deflection by a black hole in quintessence dark energy . . . . . . . . . . . . . . . . . . . . . . . . . 3 Shadows, photon rings and lensing rings with thindisk accretion . . . . . . . . . . . . . . . . . . . . . 3.1 Number of orbits of the deflected light trajectories 3.2 Observed specific intensities and transfer functions 3.3 Shadows, lensing rings and photon rings . . . . . 4 Shadows and photon spheres with spherical accretions . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Shadows and photon spheres with a static spherical accretion . . . . . . . . . . . . . . . . . . . a e-mail:

[email protected]

b e-mail:

[email protected] (corresponding author)

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4.2 Shadows and photon spheres spherical accretion . . . . . 5 Conclusions and discussions . . . References . . . . . . . . . . . . . .

with an infalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 Introduction The Event Horizon Telescope (EHT) collaboration has recently released an image of a supermassive black hole in M87 [1–6]. The image shows that there is a dark interior surrounded by a bright ring, which are called the black hole shadow and photon ring, respectively. The shadow and photon ring result from the deflections of l