scholarly journals Galaxy Formation, Evolution and Rotation as a 4D Relativistic Cloud-World Embedded in a 4D Conformal Bulk: From String to Cloud Theory

2021 ◽  
Author(s):  
Mohammed Al-Fadhli
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Early Universe ◽  
Galaxy Formation ◽  
Positive Curvature ◽  
Recent Observation ◽  
Galactic Centre ◽  
Field Equations ◽  
The Galaxy ◽  
Gas Cloud

The recent observation of the G2 gas cloud orbit around the galactic centre has challenged the model of a mere supermassive black hole that should have destroyed it. In addition, the Planck Legacy 2018 (PL18) release has preferred a positively curved early Universe with a confidence level exceeding 99%. In this study, the formation of a galaxy from the collapse of a supermassive gas cloud in the early Universe is modelled based on extended field equations as a 4D relativistic cloud-world that flows and spins through a 4D conformal bulk of an initial positive curvature considering the preference of the PL18 release. Owning to the curved background, this scenario of galaxy formation reveals that the core of the galaxy undergoes a forced vortex formation with a central event horizon leading to opposite vortices (traversable wormholes) that are spatially shrinking through evolving in the conformal time. It indicates that the galaxy and its core are formed at the same process where the surrounding gas clouds form the spiral arms due to the frame-dragging induced by the fast-rotating core. Further, the bulk conformal curvature evolution demonstrates the fast orbital speed of outer stars owing to external fields exerted on galaxies as they travel through conformally curved space-time. Accordingly, the G2 gas cloud that only faced the drag effects could be explained if its orbit is around the vortex but at a distance from the central event horizon. These findings could explain the fast orbital speed of outer stars where the galaxy formation and its core simultaneously could explain the formation of the supermassive compact galaxy cores with a mass of ~109 M⊙ at just 6% of the current Universe age and thus could resolve the black hole hierarchy problem.

scholarly journals Galaxy Formation and Rotation as a 4D Relativistic Cloud-World Embedded in a 4D Conformal Background: A Cloud Theory

2021 ◽  
Author(s):  
Mohammed Al-Fadhli
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Early Universe ◽  
Galaxy Formation ◽  
Positive Curvature ◽  
Recent Observation ◽  
Galactic Centre ◽  
Field Equations ◽  
The Galaxy ◽  
Gas Cloud

The recent observation of the G2 gas cloud orbit around the galactic centre has challenged the model of a mere supermassive black hole at the centre of our galaxy which should have destroyed it. In addition, the Planck Legacy 2018 (PL18) release has preferred a positively curved early Universe with a confidence level exceeding 99%. In this study, the collapse of a large gas cloud in the early Universe to form a galaxy is modelled based on extended field equations as a 4D relativistic CloudWorld that flows and spins through a 4D independent conformal background of an initial positive curvature considering the preference of the PL18 release. Owning to the curved background, this scenario of galaxy formation indicates that the core of the galaxy undergoes a forced vortex formation with a central event horizon leading to opposite traversable wormholes that are spatially shrinking through the conformal time. It reveals that the galaxy and its core are formed at the same process where the surrounding gas clouds form the spiral arms due to the frame-dragging induced by the fast-rotating core. Accordingly, the G2 gas cloud that only faced the drag effects could be explained if its orbit is around the wormhole but at a distance from the central event horizon. The formation of the galaxy and its core simultaneously could explain the formation of the supermassive compact galaxy cores with a mass of ~109 M⊙ at just 6% of the current Universe age and could resolve the black hole hierarchy problem.

scholarly journals Universal interferometric signatures of a black hole’s photon ring

2020 ◽  
Vol 6 (12) ◽  
pp. eaaz1310 ◽  
Author(s):  
Michael D. Johnson ◽  
Alexandru Lupsasca ◽  
Andrew Strominger ◽  
George N. Wong ◽  
Shahar Hadar ◽  
...  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Event Horizon ◽  
Infinite Sequence ◽  
High Order ◽  
Black Hole Mass ◽  
Tests Of General Relativity ◽  
Supermassive Black Hole ◽  
The Galaxy ◽  
Self Similar

The Event Horizon Telescope image of the supermassive black hole in the galaxy M87 is dominated by a bright, unresolved ring. General relativity predicts that embedded within this image lies a thin “photon ring,” which is composed of an infinite sequence of self-similar subrings that are indexed by the number of photon orbits around the black hole. The subrings approach the edge of the black hole “shadow,” becoming exponentially narrower but weaker with increasing orbit number, with seemingly negligible contributions from high-order subrings. Here, we show that these subrings produce strong and universal signatures on long interferometric baselines. These signatures offer the possibility of precise measurements of black hole mass and spin, as well as tests of general relativity, using only a sparse interferometric array.

Angular momentum in general relativity I. Definition and asymptotic behaviour

1977 ◽  
Vol 354 (1679) ◽  
pp. 379-405 ◽  
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Angular Momentum ◽  
Asymptotic Behaviour ◽  
Event Horizon ◽  
Conservation Law ◽  
General Definition ◽  
Field Equations ◽  
Spin Coefficient ◽  
Coefficient Formalism

Angular momentum in axisymmetric space-times is investigated. The conclusions lead to a general definition suitable for all asymptoticallyflat spaces which is valid both at infinity and on the event horizon of a black hole. This first paper restricts attention to considerations at infinity. Working in terms of the spin coefficient formalism, the field equations are solved asymptotically at large distances and the definition is evaluated. A conservation law is derived and finally the effect on the angular momentum of a supertranslation of the coordinates is discussed.

scholarly journals The Brightest Point in Accretion Disk and Black Hole Spin: Implication to the Image of Black Hole M87*

Universe ◽  
2019 ◽  
Vol 5 (8) ◽  
pp. 183 ◽  
Author(s):  
Vyacheslav I. Dokuchaev ◽  
Natalia O. Nazarova
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Accretion Disk ◽  
Disk Model ◽  
Dark Region ◽  
High Resolution Image ◽  
Supermassive Black Hole ◽  
Black Hole Spin ◽  
The Galaxy ◽  
Expected Position

We propose the simple new method for extracting the value of the black hole spin from the direct high-resolution image of black hole by using a thin accretion disk model. In this model, the observed dark region on the first image of the supermassive black hole in the galaxy M87, obtained by the Event Horizon Telescope, is a silhouette of the black hole event horizon. The outline of this silhouette is the equator of the event horizon sphere. The dark silhouette of the black hole event horizon is placed within the expected position of the black hole shadow, which is not revealed on the first image. We calculated numerically the relation between the observed position of the black hole silhouette and the brightest point in the thin accretion disk, depending on the black hole spin. From this relation, we derive the spin of the supermassive black hole M87*, a = 0.75 ± 0.15 .

scholarly journals THERMODYNAMICS OF BLACK HOLE IN (N+3) DIMENSIONS FROM EUCLIDEAN N-BRANE THEORY

1995 ◽  
Vol 10 (36) ◽  
pp. 2775-2782 ◽  
Author(s):  
ICHIRO ODA
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Three Dimensional ◽  
Black Hole Entropy ◽  
Particle Model ◽  
Field Equations ◽  
3 Dimensional ◽  
The Past ◽  
Dimensional Black Hole ◽  
Brane Theory

In this letter we consider an N-brane description of an (N+3)-dimensional black hole horizon. First of all, we start by examining in more detail a previous work where a string theory is used in describing the dynamics of the event horizon of a four-dimensional black hole. This is an attempt to understand the black hole thermodynamics by an effective two-dimensional field theory of the event horizon of a black hole. Then we consider a particle model defined on one-dimensional Euclidean line in a three-dimensional black hole as a target spacetime metric. By solving the field equations we find a “worldline instanton” which connects the past event horizon with the future one. This solution gives us the exact value of the Hawking temperature and to leading order the Bekenstein-Hawking formula of black hole entropy. We also show that this formalism is extensible to an arbitrary spacetime dimension. Finally we make a comment of many recent works of one-loop quantum correction to the black hole entropy.

scholarly journals A gas cloud on its way towards the supermassive black hole at the Galactic Centre

Nature ◽  
2011 ◽  
Vol 481 (7379) ◽  
pp. 51-54 ◽  
Author(s):  
S. Gillessen ◽  
R. Genzel ◽  
T. K. Fritz ◽  
E. Quataert ◽  
C. Alig ◽  
...  
Keyword(s):  
Black Hole ◽  
Galactic Centre ◽  
Supermassive Black Hole ◽  
Gas Cloud

scholarly journals Extended General Relativity for a Curved Universe

2021 ◽  
Author(s):  
Mohammed B. Al-Fadhli
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Early Universe ◽  
Cold Dark Matter ◽  
Positive Curvature ◽  
Boundary Term ◽  
Radius Of Curvature ◽  
Field Equations ◽  
Extended Field ◽  
Background Curvature

The recent Planck Legacy release revealed the presence of an enhanced lensing amplitude in the cosmic microwave background (CMB). Notably, this amplitude is higher than that estimated by the lambda cold dark matter model (ΛCDM), which endorses the positive curvature of the early Universe with a confidence level greater than 99%. Although General Relativity (GR) performs accurately in the local/present Universe where spacetime is almost flat, its lost boundary term, incompatibility with quantum mechanics and the necessity of dark matter and dark energy might indicate its incompleteness. By utilising the Einstein–Hilbert action, this study presents extended field equations considering the pre-existing/background curvature and the boundary contribution. The extended field equations consist of Einstein field equations with a conformal transformation feature in addition to the boundary term, which could remove singularities from the theory and facilitate its quantisation. The extended equations have been utilised to derive the evolution of the Universe with reference to the scale factor of the early Universe and its radius of curvature.

scholarly journals Visible Shapes of Black Holes M87* and SgrA*

Universe ◽  
2020 ◽  
Vol 6 (9) ◽  
pp. 154
Author(s):  
Vyacheslav I. Dokuchaev ◽  
Natalia O. Nazarova
Keyword(s):  
Black Hole ◽  
Event Horizon ◽  
Milky Way ◽  
Dark Spot ◽  
Disk Model ◽  
Milky Way Galaxy ◽  
Supermassive Black Hole ◽  
The Galaxy ◽  
Visible Images ◽  
Inner Parts

We review the physical origins for possible visible images of the supermassive black hole M87* in the galaxy M87 and SgrA* in the Milky Way Galaxy. The classical dark black hole shadow of the maximal size is visible in the case of luminous background behind the black hole at the distance exceeding the so-called photon spheres. The notably smaller dark shadow (dark silhouette) of the black hole event horizon is visible if the black hole is highlighted by the inner parts of the luminous accreting matter inside the photon spheres. The first image of the supermassive black hole M87*, obtained by the Event Horizon Telescope collaboration, shows the lensed dark image of the southern hemisphere of the black hole event horizon globe, highlighted by accreting matter, while the classical black hole shadow is invisible at all. A size of the dark spot on the Event Horizon Telescope (EHT) image agrees with a corresponding size of the dark event horizon silhouette in a thin accretion disk model in the case of either the high or moderate value of the black hole spin, a≳0.75.

scholarly journals Physical Properties of Schwarzschild–deSitter Event Horizon Induced by Stochastic Quantum Gravity

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 511
Author(s):  
Claudio Cremaschini ◽  
Massimo Tessarotto
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Gravity ◽  
Event Horizon ◽  
Field Equations ◽  
Central Mass ◽  
Event Horizons ◽  
Covariant Quantum ◽  
Gravitational Fields ◽  
New Type

A new type of quantum correction to the structure of classical black holes is investigated. This concerns the physics of event horizons induced by the occurrence of stochastic quantum gravitational fields. The theoretical framework is provided by the theory of manifestly covariant quantum gravity and the related prediction of an exclusively quantum-produced stochastic cosmological constant. The specific example case of the Schwarzschild–deSitter geometry is looked at, analyzing the consequent stochastic modifications of the Einstein field equations. It is proved that, in such a setting, the black hole event horizon no longer identifies a classical (i.e., deterministic) two-dimensional surface. On the contrary, it acquires a quantum stochastic character, giving rise to a frame-dependent transition region of radial width δr between internal and external subdomains. It is found that: (a) the radial size of the stochastic region depends parametrically on the central mass M of the black hole, scaling as δr∼M3; (b) for supermassive black holes δr is typically orders of magnitude larger than the Planck length lP. Instead, for typical stellar-mass black holes, δr may drop well below lP. The outcome provides new insight into the quantum properties of black holes, with implications for the physics of quantum tunneling phenomena expected to arise across stochastic event horizons.

Outflows and Jets

2014 ◽  
Author(s):  
Charles D. Bailyn
Keyword(s):  
Black Hole ◽  
Kinetic Energy ◽  
Event Horizon ◽  
Accretion Disk ◽  
Observational Evidence ◽  
Accretion Flows ◽  
Accretion Process ◽  
The Galaxy

This chapter looks at the presence of outflows or jets, a somewhat unexpected feature of accretion flows. There is strong observational evidence that some fraction of the infalling material reverses course near the accreting object and is shot out perpendicularly to the accretion disk. In some cases, narrow collimated beams of emission are observed emerging from the central-most regions of galaxies and continuing across the whole of the galaxy, depositing their energy hundreds of kiloparsecs away from their origin. These phenomena are sometimes described as jets “emerging” from a black hole. This parlance is misleading—the jets do not, and indeed could not, emerge from inside the event horizon. Rather, some mechanism redirects the energy generated by the accretion process into a fraction of the infalling material and provides enough bulk kinetic energy for the material to escape the accretion process before the material enters the event horizon.

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