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Question Condensates

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Apr 13, 2021
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Terms used by some;
Exotic Stars, Strange Stars, Neutron Stars, Quark Stars, Kaon Stars, Electroweak Stars, Preo Stars, Partonic Stars, Boson Star, Procar Stars, Axion Gluon Stars, Bose-Einstein Condensates etc etc.
I would say, research and research, the answers are still in discussion, saying that there is 1000s of papers written by scientists.
 
Apr 13, 2021
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High Energy Physics - Theory
[Submitted on 20 Oct 2021 (v1), last revised 30 Dec 2021 (this version, v2)]
Re-examining the stability of rotating horizonless black shells mimicking Kerr black holes
Ulf Danielsson, Suvendu Giri
In arXiv:1705.10172 a string theory inspired alternative to gravitational collapse was proposed, consisting of a bubble of AdS space made up of ingredients from string theory. These ultra compact objects are 9/8 times the size of the corresponding Schwarzschild black hole, but being within the photosphere are almost indistinguishable from them. Slowly rotating counterparts of these black shells were constructed in arXiv:1712.00511, which closely mimic a Kerr black hole, but have a quadrupole moment that differs from Kerr. Recently, arXiv:2109.09814 studied the dynamical stability of the stationary black shells against radial perturbations and accretion of matter, and examined a two parameter family of fluxes required for stability. In this paper, we re-examine the rotating black shells with particular attention to the constraints imposed by this dynamical analysis for non-rotating shells. Extrapolating these results to rotating shells, we find that they can indeed support themselves at a critical point in the gravitational potential. Additionally, requiring that they settle back to their new Buchdahl radius after accreting matter, uniquely fixes the fluxes required for dynamical stability. The flux parameters turn out to have an extremely simple form, and fulfil one of the constraints for perturbative radial stability while exactly saturating the other. The preferred quadrupole moment that we find, given some physical assumptions, is 7% less than Kerr.
Comments:10 pages
Subjects:High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
Journal reference:Phys. Rev. D 104, 124086 (2021)
DOI:10.1103/PhysRevD.104.124086
Report number:UUITP-49/21
Cite as:arXiv:2110.10542 [hep-th]
(or arXiv:2110.10542v2 [hep-th] for this version)
 
Apr 13, 2021
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General Relativity and Quantum Cosmology
[Submitted on 17 Aug 2021]
Quantum optics meets black hole thermodynamics via conformal quantum mechanics: II. Thermodynamics of acceleration radiation
A. Azizi, H. E. Camblong, A. Chakraborty, C. R. Ordonez, M. O. Scully
The thermodynamics of ``horizon brightened acceleration radiation'' (HBAR), due to a random atomic cloud freely falling into a black hole in a Boulware-like vacuum, is shown to mimic the thermodynamics of the black hole itself. The thermodynamic framework is developed in its most general form via a quantum optics master equation, including rotating (Kerr) black holes and for any set of initial conditions of the atomic cloud. The HBAR field exhibits thermal behavior at the Hawking temperature and an area-entropy-flux relation that resembles the Bekenstein-Hawking entropy. In addition, this general approach reveals:(i) the existence of an HBAR-black-hole thermodynamic correspondence that explains the HBAR area-entropy-flux relation;(ii) the origin of the field entropy from the near-horizon behavior, via conformal quantum mechanics (CQM).
Comments:31 pages, 1 figure
Subjects:General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th); Quantum Physics (quant-ph)
DOI:10.1103/PhysRevD.104.084085
Cite as:arXiv:2108.07572 [gr-qc]
(or arXiv:2108.07572v1 [gr-qc] for this version)

Why I’m posting such work is to indicate what scientists are looking at, this is a drop in the bucket.
 
Apr 13, 2021
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General Relativity and Quantum Cosmology
[Submitted on 10 Jul 2021]
Motion of test particle in rotating boson star
Yu-Peng Zhang, Yan-Bo Zeng, Yong-Qiang Wang, Shao-Wen Wei, Yu-Xiao Liu
Motion of a test particle plays an important role in understanding the properties of a spacetime. As a new type of the strong gravity system, boson stars could mimic black holes located at the center of galaxies. Studying the motion of a test particle in the spacetime of a rotating boson star will provide the astrophysical observable effects if a boson star is located at the center of a galaxy. In this paper, we investigate the timelike geodesic of a test particle in the background of a rotating boson star with angular number m=(1,2,3). With the change of angular number and frequency, a rotating boson star will transform from the low rotating state to the highly relativistic rapidly rotating state, the corresponding Lense-Thirring effects will be more and more significant and it should be studied in detail. By solving the four-velocity of a test particle and integrating the geodesics, we investigate the bound orbits with a zero and nonzero angular momentum. We find that a test particle can stay more longer time in the central region of a boson star when the boson star becomes from low rotating state to highly relativistic rotating state. Such behaviors of the orbits are quite different from the orbits in a Kerr black hole, and the observable effects from these orbits will provide a rule to investigate the astrophysical compact objects in the Galactic center.
Comments:comments are welcome
Subjects:General Relativity and Quantum Cosmology (gr-qc)
Cite as:arXiv:2107.04848 [gr-qc]
(or arXiv:2107.04848v1 [gr-qc] for this version)

How can man be so advance in the short period on Earth
 
Apr 13, 2021
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High Energy Physics - Theory
[Submitted on 31 Jul 2021 (v1), last revised 11 Oct 2021 (this version, v2)]
Inflation and Supersymmetry Breaking in Higgs-R2 Supergravity
Shuntaro Aoki, Hyun Min Lee, Adriana G. Menkara
We propose a new construction of the supergravity inflation as an UV completion of the Higgs-R2 inflation. In the dual description of R2-supergravity, we show that there appear dual chiral superfields containing the scalaron or sigma field in the Starobinsky inflation, which unitarizes the supersymmetric Higgs inflation with a large non-minimal coupling up to the Planck scale. We find that a successful slow-roll inflation is achievable in the Higgs-sigma field space, but under the condition that higher curvature terms are introduced to cure the tachyonic mass problems for spectator singlet scalar fields. We also discuss supersymmetry breaking and its transmission to the visible sector as a result of the couplings of the dual chiral superfields and the non-minimal gravity coupling of the Higgs fields.
Comments:32 pages, 5 figures. v2 : Minor corrections, references added
Subjects:High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
DOI:10.1007/JHEP10(2021)178
Cite as:arXiv:2108.00222 [hep-th]
(or arXiv:2108.00222v2 [hep-th] for this version)

To fully understand one needs to go where no man has gone before, to explore the unexplored, to look at processes that are too far fetched, regardless of the negative or positive critics.
 
Apr 13, 2021
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General Relativity and Quantum Cosmology
[Submitted on 23 Dec 2021]
Boson stars and black holes with wavy scalar hair
Yves Brihaye (Université de Mons, Belgium), Betti Hartmann (University College London, UK)
In this paper, we follow up on the discovery of a new type of solution in the Einstein-Maxwell system coupled minimally to a self-interacting complex scalar field. For sufficiently large gravitational coupling and sufficiently small electromagnetic coupling we demonstrate that boson stars as well as black holes can carry scalar hair that shows a distinct new feature: a number of spatial oscillations in the scalar field away from the core or horizon, respectively. These spatial oscillations appear also in the curvature invariants and hence should be a detectable feature of the space-time. As a first hint that this is true, we show that the effective potential for null geodesics in this space-time possesses a local minimum indicating that in the spatial region where oscillations occur a new stable photon sphere should be possible. We also study the interior of the black holes with scalar hair and show that the curvature singularity appears at a finite value of the radius and that black holes with wavy scalar hair have this singularity very close to the center.
Subjects:General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
Cite as:arXiv:2112.12830 [gr-qc]
(or arXiv:2112.12830v1 [gr-qc] for this version)

Slowly slowly we are getting closer to understanding varies types of stars.
 

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