scholarly journals Loosely trapped surface and dynamically transversely trapping surface in Einstein–Maxwell systems

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Kangjae Lee ◽  
Tetsuya Shiromizu ◽  
Hirotaka Yoshino ◽  
Keisuke Izumi ◽  
Yoshimune Tomikawa
Keyword(s):  
Black Hole ◽  
Energy Density ◽  
Electromagnetic Fields ◽  
Upper Bound ◽  
Correction Term ◽  
Strong Gravity ◽  
Black Hole Spacetimes ◽  
Trapped Surface

Abstract We study the properties of the loosely trapped surface (LTS) and the dynamically transversely trapping surface (DTTS) in Einstein–Maxwell systems. These concepts of surfaces were proposed by four of the present authors in order to characterize strong gravity regions. We prove the Penrose-like inequalities for the area of LTSs/DTTSs. Interestingly, although the naively expected upper bound for the area is that of the photon sphere of a Reissner–Nordström black hole with the same mass and charge, the obtained inequalities include corrections represented by the energy density or pressure/tension of electromagnetic fields. Due to this correction, the Penrose-like inequality for the area of LTSs is tighter than the naively expected one. We also evaluate the correction term numerically in the Majumdar–Papapetrou two-black-hole spacetimes.

scholarly journals The swampland at large number of space-time dimensions

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Quentin Bonnefoy ◽  
Luca Ciambelli ◽  
Dieter Lüst ◽  
Severin Lüst
Keyword(s):  
Black Hole ◽  
Upper Bound ◽  
Space Time ◽  
Large Dimension ◽  
De Sitter ◽  
Black Hole Spacetimes ◽  
Characteristic Radius ◽  
Kaluza Klein ◽  
Dimension Conjecture

Abstract We discuss some aspects of swampland constraints — especially the swamp-land distance conjecture — in a large number of space-time dimensions D. We analyze Kaluza-Klein (KK) states at large D and find that some KK spectra possess an interesting dependence on D. On the basis of these observations we propose a new large dimension conjecture. We apply it to KK states of compactifications to anti-de Sitter backgrounds where it predicts an upper bound on the dimension of space-time as a function of its characteristic radius. We also apply our conjecture to black hole spacetimes, whose entropies have a D-dependence very similar to that of the KK spectrum.

scholarly journals Stable circular orbits in caged black hole spacetimes

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
Takahisa Igata ◽  
Shinya Tomizawa
Keyword(s):  
Black Hole ◽  
Circular Orbits ◽  
Black Hole Spacetimes

scholarly journals Master equations and quasinormal modes of spin- 3/2 fields in Schwarzschild (A)dS black hole spacetimes

2019 ◽  
Vol 100 (10) ◽  
Author(s):  
Chun-Hung Chen ◽  
Hing-Tong Cho ◽  
Alan S. Cornell ◽  
Gerhard E. Harmsen
Keyword(s):  
Black Hole ◽  
Quasinormal Modes ◽  
Master Equations ◽  
Black Hole Spacetimes

OBSERVATIONAL CONSTRAINTS ON STRONG GRAVITY

2011 ◽  
Vol 20 (14) ◽  
pp. 2755-2760
Author(s):  
CHRIS DONE
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Strong Field ◽  
Field Tests ◽  
High Energy ◽  
Observational Constraints ◽  
Tests Of General Relativity ◽  
Strong Gravity ◽  
Accretion Flows ◽  
Spacetime Curvature

Accretion onto a black hole transforms the darkest objects in the universe to the brightest. The high energy radiation emitted from the accretion flow before it disappears forever below the event horizon lights up the regions of strong spacetime curvature close to the black hole, enabling strong field tests of General Relativity. I review the observational constraints on strong gravity from such accretion flows, and show how the data strongly support the existence of such fundamental General Relativistic features of a last stable orbit and the event horizon. However, these successes also imply that gravity does not differ significantly from Einstein's predictions above the event horizon, so any new theory of quantum gravity will be very difficult to test.

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