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4,540 results on '"Gray, D. A."'

3. RCCZ4: A Reference Metric Approach to Z4

Author

Reid, Gray D. and Choptuik, Matthew W.

Subjects
General Relativity and Quantum Cosmology
Abstract

The hyperbolic formulations of numerical relativity due to Baumgarte, Shapiro, Shibata & Nakamura (BSSN) and Nagy Ortiz & Reula (NOR), among others, achieve stability through the effective embedding of general relativity within the larger Z4 system. In doing so, various elliptic constraints are promoted to dynamical degrees of freedom, permitting the advection of constraint violating modes. Here we demonstrate that it is possible to achieve equivalent performance through a modification of fully covariant and conformal Z4 (FCCZ4) wherein constraint violations are coupled to a reference metric completely independently of the physical metric. We show that this approach works in the presence of black holes and holds up robustly in a variety of spherically symmetric simulations including the critical collapse of a scalar field. We then demonstrate that our formulation is strongly hyperbolic through the use of a pseudodifferential first order reduction and compare its hyperbolicity properties to those of FCCZ4 and generalized BSSN (GBSSN). Our present approach makes use of a static Lorentzian reference metric and does not appear to provide significant advantages over FCCZ4. However, we speculate that dynamical specification of the reference metric may provide a means of exerting greater control over constraint violations than what is provided by current BSSN-type formulations., Comment: 19 pages, 18 figures

Published
2023

4. Stability of Non-Minimally Coupled Topological-Defect Boson Stars

Author

Reid, Gray D. and Choptuik, Matthew W.

Subjects
General Relativity and Quantum Cosmology
Abstract

As shown by Marunovic and Murkovic, non-minimal d-stars, composite structures consisting of a boson star and a global monopole non-minimally coupled to the general relativistic field, can have extremely high gravitational compactness. In a previous paper we demonstrated that these ground-state stationary solutions are sometimes additionally characterized by shells of bosonic matter located far from the center of symmetry. In order to investigate the question of stability posed by Marunovic and Murkovic, we investigate the stability of several families of d-stars using both numerical simulations and linear perturbation theory. For all families investigated, we find that the most highly compact solutions, along with those solutions exhibiting shells of bosonic matter, are unstable to radial perturbations and are therefore poor candidates for astrophysically-relevant black hole mimickers or other highly compact stable objects., Comment: 19 pages, 24 figures

Published
2023

5. Universality in the Critical Collapse of the Einstein-Maxwell System

Author

Reid, Gray D. and Choptuik, Matthew W.

Subjects
General Relativity and Quantum Cosmology
Abstract

We report on critical phenomena in the gravitational collapse of the electromagnetic field in axisymmetry using cylindrical coordinates. We perform detailed numerical simulations of four families of dipole and quadrupole initial data fine-tuned to the onset of black hole formation. It has been previously observed that families which bifurcate into two on-axis critical solutions exhibit distinct growth characteristics from those which collapse at the centre of symmetry. In contrast, our results indicate similar growth characteristics and periodicity across all families of initial data, including those examined in earlier works. More precisely, for all families investigated, we observe power-law scaling for the maximum of the electromagnetic field invariant ($\mathrm{max}|F_{\mu\nu}F^{\mu\nu}| \sim |p-p^{\star}|^{-2\gamma}$) with $\gamma \approx 0.149(9)$. We find evidence of approximate discrete self-similarity in near-critical time evolutions with a log-scale echoing period of $\Delta \approx 0.62(8)$ across all families of initial data. Our methodology, while reproducing the results of prior studies up to a point, provides new insights into the later stages of critical searches and we propose a mechanism to explain the observed differences between our work and the previous calculations., Comment: 16 pages, 14 figures

Published
2023

7. Methanol

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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9. Toluene

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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10. 1,2-Dichloroethane

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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11. Pentachloroethane

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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13. Dimethylamine

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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14. 2-Methoxyethanol

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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15. Carbon Disulfide

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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16. Ethyl Acetate

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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17. Chloropentafluoroethane

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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18. 1,2-Xylene

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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19. Di-n-butylamine

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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20. n-Butyl Acetate

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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21. Isopropanol

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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22. Acetic Acid

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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23. n-Amyl Acetate

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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25. 1,2-Propanediol

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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26. Bromodichloromethane

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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27. Carbon Tetrachloride

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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28. Methyl Isobutyl Ketone

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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29. Furan

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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30. Ethylene Glycol

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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31. Ethanol

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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32. n-Propanol

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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33. Acetone

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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35. Isobutyl Acetate

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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37. Methyl n-Propyl Ketone

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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38. t-Butylamine

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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40. Methyl Ethyl Ketone

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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42. n-Butylamine

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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43. Ethyl Chloride

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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44. 2-Nitropropane

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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46. Ethyl Formate

Author

Howard, Philip H., primary, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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47. Dimethyl Ether

Author

Howard, Philip H., primary, Michalenko, Edward M., additional, Meylan, William M., additional, Basu, Dipak K., additional, Beauman, Julie A., additional, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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48. Diethylene Glycol Monobutyl Ether

Author

Howard, Philip H., primary, Michalenko, Edward M., additional, Meylan, William M., additional, Basu, Dipak K., additional, Beauman, Julie A., additional, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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49. 2-Hydroxypropanenitrile

Author

Howard, Philip H., primary, Michalenko, Edward M., additional, Meylan, William M., additional, Basu, Dipak K., additional, Beauman, Julie A., additional, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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50. 1,1'-Oxydi-2-propanol

Author

Howard, Philip H., primary, Michalenko, Edward M., additional, Meylan, William M., additional, Basu, Dipak K., additional, Beauman, Julie A., additional, Sage, Gloria W., additional, Jarvis, William F., additional, and Gray, D. Anthony, additional

Published
2023
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