scholarly journals Late-time evolution of nonlinear gravitational collapse

1997 ◽  
Vol 56 (12) ◽  
pp. 7820-7832 ◽  
Author(s):  
Lior M. Burko ◽  
Amos Ori
Keyword(s):  
Time Evolution ◽  
Gravitational Collapse ◽  
Late Time

scholarly journals Formation, vertex deviation, and age of the Milky Way’s bulge: input from a cosmological simulation with a late-forming bar

2019 ◽  
Vol 485 (4) ◽  
pp. 5073-5085 ◽  
Author(s):  
Victor P Debattista ◽  
Oscar A Gonzalez ◽  
Robyn E Sanderson ◽  
Kareem El-Badry ◽  
Shea Garrison-Kimmel ◽  
...  
Keyword(s):  
Time Evolution ◽  
Milky Way ◽  
Late Time ◽  
High Latitudes ◽  
Older Populations

Abstract We present the late-time evolution of m12m, a cosmological simulation of a Milky Way-like galaxy from the FIRE project. The simulation forms a bar after redshift z = 0.2. We show that the evolution of the model exhibits behaviours typical of kinematic fractionation, with a bar weaker in older populations, an X-shape traced by the younger, metal-rich populations, and a prominent X-shape in the edge-on mean metallicity map. Because of the late formation of the bar in m12m, stars forming after $10\mbox{$\:{\rm Gyr}$}$ (z = 0.34) significantly contaminate the bulge, at a level higher than is observed at high latitudes in the Milky Way, implying that its bar cannot have formed as late as in m12m. We also study the model’s vertex deviation of the velocity ellipsoid as a function of stellar metallicity and age in the equivalent of Baade’s Window. The formation of the bar leads to a non-zero vertex deviation. We find that metal-rich stars have a large vertex deviation (∼40°), which becomes negligible for metal-poor stars, a trend also found in the Milky Way, despite not matching in detail. We demonstrate that the vertex deviation also varies with stellar age and is large for stars as old as $9 \mbox{$\:{\rm Gyr}$}$, while $13\mbox{$\:{\rm Gyr}$}$ old stars have negligible vertex deviation. When we exclude stars that have been accreted, the vertex deviation is not significantly changed, demonstrating that the observed variation of vertex deviation with metallicity is not necessarily due to an accreted population.

scholarly journals Vacuum Energy Decay from a q-Bubble

Physics ◽  
2019 ◽  
Vol 1 (3) ◽  
pp. 321-338 ◽  
Author(s):  
Frans R. Klinkhamer ◽  
Osvaldo P. Santillán ◽  
Grigory E. Volovik ◽  
Albert Zhou
Keyword(s):  
Cosmological Constant ◽  
Time Evolution ◽  
Gravitational Collapse ◽  
Vacuum Energy ◽  
Finite Size ◽  
Energy Scale ◽  
Gravitational Energy ◽  
Numerical Results ◽  
Field Energy ◽  
Spherical Bubble

We consider a finite-size spherical bubble with a nonequilibrium value of the q-field, where the bubble is immersed in an infinite vacuum with the constant equilibrium value q 0 for the q-field (this q 0 has already cancelled an initial cosmological constant). Numerical results are presented for the time evolution of such a q-bubble with gravity turned off and with gravity turned on. For small enough bubbles and a q-field energy scale sufficiently below the gravitational energy scale E Planck , the vacuum energy of the q-bubble is found to disperse completely. For large enough bubbles and a finite value of E Planck , the vacuum energy of the q-bubble disperses only partially and there occurs gravitational collapse near the bubble center.

scholarly journals Late time evolution of a nonminimally coupled scalar field system

2019 ◽  
Vol 51 (9) ◽  
Author(s):  
M. Shahalam ◽  
R. Myrzakulov ◽  
Maxim Yu. Khlopov
Keyword(s):  
Scalar Field ◽  
Time Evolution ◽  
Late Time ◽  
Field System

scholarly journals Late time evolution of negatively curved FLRW models

2020 ◽  
Vol 135 (4) ◽  
Author(s):  
Roberto Giambò ◽  
John Miritzis ◽  
Annagiulia Pezzola
Keyword(s):  
Time Evolution ◽  
Late Time ◽  
Negatively Curved
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