Dark energy in thermal equilibrium with the cosmological horizon?

AbstractWe 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.

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THERMODYNAMICAL PROPERTIES OF DARK ENERGY IN LOOP QUANTUM COSMOLOGY

International Journal of Modern Physics D ◽

10.1142/s0218271811018731 ◽

2011 ◽

Vol 20 (02) ◽

pp. 169-179

Author(s):

KUI XIAO ◽

JIAN-YANG ZHU

Keyword(s):

Dark Energy ◽

Equation Of State ◽

Quantum Cosmology ◽

Thermal Equilibrium ◽

Apparent Horizon ◽

State Parameter ◽

Loop Quantum Cosmology ◽

Thermodynamical Properties ◽

The One ◽

Modified Entropy

Considering an arbitrary, varying equation of state parameter, the thermodynamical properties of dark energy fluid in the semiclassical loop quantum cosmology scenario, where we consider the inverse volume modification, are studied. The equation of state parameters are corrected when we consider the effective behavior. Assuming that the apparent horizon has Hawking temperature, the modified entropy–area relation is obtained, and we find that this relation is different from the one which is obtained by considering the holonomy correction. Considering that the dark energy is in thermal equilibrium with the Hawking radiation of the apparent horizon, we get the expression for the entropy of the dark energy fluid.

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The price of curiosity: information recovery in de Sitter space

Journal of High Energy Physics ◽

10.1007/jhep05(2021)291 ◽

2021 ◽

Vol 2021 (5) ◽

Author(s):

Lars Aalsma ◽

Watse Sybesma

Keyword(s):

Black Hole ◽

Thermal Equilibrium ◽

De Sitter Space ◽

Cosmological Horizon ◽

De Sitter ◽

Information Recovery ◽

Fine Grained ◽

Black Hole Radiation ◽

Entropy Of Black Hole

Abstract Recent works have revealed that quantum extremal islands can contribute to the fine-grained entropy of black hole radiation reproducing the unitary Page curve. In this paper, we use these results to assess if an observer in de Sitter space can decode information hidden behind their cosmological horizon. By computing the fine-grained entropy of the Gibbons-Hawking radiation in a region where gravity is weak we find that this is possible, but the observer’s curiosity comes at a price. At the same time the island appears, which happens much earlier than the Page time, a singularity forms which the observer will eventually hit. We arrive at this conclusion by studying de Sitter space in Jackiw-Teitelboim gravity. We emphasize the role of the observer collecting radiation, breaking the thermal equilibrium studied so far in the literature. By analytically solving for the backreacted geometry we show how an island appears in this out-of-equilibrium state.

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Dark energy model with generalized cosmological horizon

Journal of Experimental and Theoretical Physics ◽

10.1134/s1063776114100100 ◽

2014 ◽

Vol 119 (4) ◽

pp. 668-676

Author(s):

M. Sharif ◽

A. Jawad

Keyword(s):

Dark Energy ◽

Dark Energy Model ◽

Energy Model ◽

Cosmological Horizon

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Dark energy and cosmological horizon thermal effects

Physical Review D ◽

10.1103/physrevd.103.043514 ◽

2021 ◽

Vol 103 (4) ◽

Author(s):

Artyom V. Astashenok ◽

Sergei D. Odintsov ◽

V. K. Oikonomou

Keyword(s):

Dark Energy ◽

Thermal Effects ◽

Cosmological Horizon

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Next Generation Design and Prospects for Cannex

Universe ◽

10.3390/universe7070234 ◽

2021 ◽

Vol 7 (7) ◽

pp. 234

Author(s):

René I. P. Sedmik ◽

Mario Pitschmann

Keyword(s):

Dark Matter ◽

Dark Energy ◽

Present Article ◽

Thermal Equilibrium ◽

Parallel Plates ◽

Casimir Forces ◽

Plane Parallel ◽

Systematic Effects ◽

Implementation Stage ◽

Proof Of Principle

The Casimir And Non-Newtonian force EXperiment (Cannex) implements the unique geometry of macroscopic plane parallel plates that guarantees an optimum sensitivity with respect to interfacial forces and their gradients. Based on experience from the recently completed proof-of-principle phase, we have started a re-design of the setup aiming to reduce systematic effects and maximize the achievable sensitivity. Several propositions have been made to measure Casimir forces in and out of thermal equilibrium, hypothetical axion and axion-like dark matter interactions, and forces originating from chameleon or symmetron dark energy interactions. In the present article, we give details on the design for the next implementation stage of Cannex and discuss the experimental opportunities, as well as limitations expected for this new setup.

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