scholarly journals Spin of primordial black holes in the model with collapsing domain walls

2021 ◽  
Vol 2021 (12) ◽  
pp. 041
Author(s):  
Yu. N. Eroshenko
Keyword(s):  
Black Holes ◽  
Domain Wall ◽  
Domain Walls ◽  
Primordial Black Holes ◽  
Spin Accumulation ◽  
Massive Black Holes ◽  
Gravitational Perturbations ◽  
Spin Parameter ◽  
Vector Mode ◽  
Density Inhomogeneities

Abstract The angular momentum (spin) acquisition by a collapsing domain wall at the cosmological radiation-dominated stage is investigated. During the collapses, primordial black holes and their clusters can be born in various mass ranges. Spin accumulation occurs under the influence of tidal gravitational perturbations from the surrounding density inhomogeneities at the epoch when the domain wall crosses the cosmological horizon. It is shown that the dimensionless spin parameter can have the small values aS  < 1 only for primordial black holes with masses M > 10-3M☉, whereas less massive black holes receive extreme spins aS  ≃ 1. It is possible that primordial black holes obtain an additional spin due to the vector mode of perturbations.

scholarly journals Primordial black holes from cosmic domain walls

2020 ◽  
Vol 101 (2) ◽  
Author(s):  
Jing Liu ◽  
Zong-Kuan Guo ◽  
Rong-Gen Cai
Keyword(s):  
Black Holes ◽  
Domain Walls ◽  
Primordial Black Holes

scholarly journals Implications of primordial black holes on the first stars and the origin of the super-massive black holes

2009 ◽  
Vol 399 (3) ◽  
pp. 1347-1356 ◽  
Author(s):  
Cosimo Bambi ◽  
Douglas Spolyar ◽  
Alexander D. Dolgov ◽  
Katherine Freese ◽  
Marta Volonteri
Keyword(s):  
Black Holes ◽  
Primordial Black Holes ◽  
First Stars ◽  
Massive Black Holes

The direct determination of magnetic domain wall profiles using a split detector STEM

1978 ◽  
Vol 36 (1) ◽  
pp. 466-467
Author(s):  
J.N. Chapman ◽  
P.E. Batson ◽  
E.M. Waddell ◽  
R.P. Ferrier
Keyword(s):  
Electron Microscope ◽  
Domain Wall ◽  
Transmission Electron Microscope ◽  
Domain Walls ◽  
Photographic Plate ◽  
Magnetic Domain ◽  
Direct Determination ◽  
Quantitative Information ◽  
Scanning Transmission Electron Microscope ◽  
Transmission Electron

By far the most commonly used mode of Lorentz microscopy in the examination of ferromagnetic thin films is the Fresnel or defocus mode. Use of this mode in the conventional transmission electron microscope (CTEM) is straightforward and immediately reveals the existence of all domain walls present. However, if such quantitative information as the domain wall profile is required, the technique suffers from several disadvantages. These include the inability to directly observe fine image detail on the viewing screen because of the stringent illumination coherence requirements, the difficulty of accurately translating part of a photographic plate into quantitative electron intensity data, and, perhaps most severe, the difficulty of interpreting this data. One solution to the first-named problem is to use a CTEM equipped with a field emission gun (FEG) (Inoue, Harada and Yamamoto 1977) whilst a second is to use the equivalent mode of image formation in a scanning transmission electron microscope (STEM) (Chapman, Batson, Waddell, Ferrier and Craven 1977), a technique which largely overcomes the second-named problem as well.

The need of electron microscopy in the study of domains and domain walls in ferroelectrics

1994 ◽  
Vol 52 ◽  
pp. 550-551
Author(s):  
Wenwu Cao
Keyword(s):  
Domain Wall ◽  
Domain Walls ◽  
High Mobility ◽  
Continuum Theory ◽  
Polarization Vector ◽  
Ferroelectric Materials ◽  
Dielectric Constants ◽  
Nonlocal Coupling ◽  
Cubic Symmetry ◽  
Gradient Energy

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,

Cosmology, primordial black holes, and supermassive particles

1985 ◽  
Vol 145 (3) ◽  
pp. 369 ◽  
Author(s):  
A.G. Polnarev ◽  
M.Yu. Khlopov
Keyword(s):  
Black Holes ◽  
Primordial Black Holes
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