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Cosmology, Relativity, and Gravity Commons™
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- Black holes (3)
- Numerical relativity (3)
- Cosmology (2)
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- Bona-Masso (1)
- Bondi accretion (1)
- Charged black holes (1)
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- Slicing conditions (1)
- Trumpet coordinates (1)
- Trumpet slices (1)
- Waves (1)
Articles 1 - 5 of 5
Full-Text Articles in Cosmology, Relativity, and Gravity
Properties Of Slicing Conditions For Charged Black Holes, Sean E. Li
Properties Of Slicing Conditions For Charged Black Holes, Sean E. Li
Honors Projects
We consider an earlier analysis by Baumgarte and de Oliveira (2022) of static Bona-Massó slices of stationary, nonrotating, uncharged black holes, represented by Schwarzschild spacetimes, and generalize that approach to Reissner-Nordström (RN) spacetimes, representing stationary, nonrotating black holes that carry a nonzero charge. This charge is parametrized by the charge-to-mass ratio λ ≡ Q/M, where M is the black-hole mass and the charge Q may represent electrical charge or act as a placeholder for extensions of general relativity. We use a height-function approach to construct time-independent, spherically symmetric slices that satisfy a so-called Bona-Massó slicing condition. We …
Accretion Onto A Black Hole At The Center Of A Neutron Star: Nuclear Equations Of State, Sophia Christina Schnauck
Accretion Onto A Black Hole At The Center Of A Neutron Star: Nuclear Equations Of State, Sophia Christina Schnauck
Honors Projects
A recent re-examination of Bondi accretion (see Richards, Baumgarte and Shapiro (2021)) revealed that, for stiff equations of state (EOSs), steady-state accretion can only occur for accretion rates exceeding a certain minimum. To date, this result has been explored only for gamma-law equations of state. Instead, we consider accretion onto a small black hole residing at the center of a neutron star governed by a more realistic nuclear EOS. We generalize the relativistic Bondi solution for such EOSs, approximated by piecewise polytropes, and thereby obtain analytical expressions for the accretion rates which were reflected in our numerical simulations. After taking …
Critical Phenomena In The Gravitational Collapse Of Electromagnetic Dipole And Quadrupole Waves, Maria F. Perez Mendoza
Critical Phenomena In The Gravitational Collapse Of Electromagnetic Dipole And Quadrupole Waves, Maria F. Perez Mendoza
Honors Projects
We report on critical phenomena in the gravitational collapse of electromagnetic waves. Generalizing earlier results that focused on dipole electromagnetic waves, we here compare with quadrupole waves in axisymmetry. We perform numerical simulations of dipole and quadrupole wave initial data, fine-tuning both sets of data to the onset of black hole formation in order to study the critical solution and related critical phenomena. We observe that different multipole moments have different symmetries, indicating that the critical solution for electromagnetic waves cannot be unique, at least not globally. This is confirmed in our numerical simulations: while dipole data lead to a …
Cosmological Gravitational Waves: Refining A General Rule Of Thumb For Reheating, David Zhou
Cosmological Gravitational Waves: Refining A General Rule Of Thumb For Reheating, David Zhou
Honors Projects
There are predictions for cosmological gravitational wave backgrounds from reheating based on various models. But, these predictions do not address the question of how an observed spectrum relates back to an unknown model or parameter. Given this problem, we have numerically and analytically investigated a variety of chaotic inflation models and their gravitational wave spectra. In doing so, we found a power law relation between gravitational wave peak frequency and an underlying chaotic inflation parameter. We found a two-class amplitude puzzle related to how strongly a matter producing field is coupled to the inflaton. We estimated the parameter describing how …
Bondi Accretion In Trumpet Geometries, August J. Miller
Bondi Accretion In Trumpet Geometries, August J. Miller
Honors Projects
The Bondi solution, which describes the radial inflow of a gas onto a non-rotating black hole, provides a powerful test for numerical relativistic codes. However, this solution is typically derived in Schwarzschild coordinates, which are not well suited for dynamical spacetime evolutions. Instead, many current numerical relativistic codes adopt moving-puncture coordinates, which render black holes in trumpet geometries. Here we transform the Bondi solution into two different trumpet coordinate systems, both of which result in regular expressions for the fluid flow extending into the black hole interior. We also evolve these solutions numerically and demonstrate their usefulness for testing and …