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Full-Text Articles in Physics
Adding Light To The Gravitational Waves On The Null Cone, Maria Babiuc-Hamilton
Adding Light To The Gravitational Waves On The Null Cone, Maria Babiuc-Hamilton
Maria C. Babiuc-Hamilton
Recent interesting astrophysical observations point towards a multi-messenger, multi-wavelength approach to understanding strong gravitational sources, like compact stars or black hole collisions, supernovae explosions, or even the big bang. Gravitational radiation is properly defined only at future null infinity, but usually is estimated at a finite radius, and then extrapolated. Our group developed a characteristic waveform extraction tool, implemented in an open source code, which computes the gravitational waves infinitely far from their source, in terms of compactified null cones, by numerically solving Einstein equation in Bondi space-time coordinates. The goal is extend the capabilities of the code, by solving …
Steps Towards The Well-Posedness Of The Characteristic Evolution For The Einstein Equations, Maria Babiuc-Hamilton
Steps Towards The Well-Posedness Of The Characteristic Evolution For The Einstein Equations, Maria Babiuc-Hamilton
Maria C. Babiuc-Hamilton
The correct modeling of gravitational radiation is a key requirement for a meaningful detection and interpretation of data. The Cauchy-characteristic technique connects the strong-field Cauchy evolution of the space-time near the black-hole merger to the characteristic evolution at future null infinity, where the waveform is properly defined. The PITT Null code, publicly available, is the most precise and refined computational method for the extraction of gravitational waves, but is not well-posed. The numerical relativity community recognizes that a well-posed problem is the only way to ensure that a code is stable and dependable. The well-posedness of the null-timelike problem for …
Gravitational And Electromagnetic Waves On The Null Cone, Maria Babiuc-Hamilton
Gravitational And Electromagnetic Waves On The Null Cone, Maria Babiuc-Hamilton
Maria C. Babiuc-Hamilton
Gravitational radiation is properly defined only at future null infinity, but mathematically it is estimated at a finite radius, and then extrapolated. Our group developed a characteristic waveform extraction tool, implemented in an open source code, which computes the gravitational waves infinitely far from their source, in terms of compactified null cones, by numerically solving Einstein equation. We add electromagnetic waves to the null cone, by deriving a formulation of the Einstein-Maxwell equations suitable to be numerically implemented into a characteristic code, that will evolve and calculate both the gravitational waves and their electromagnetic counterparts all the way to infinity.
Well-Posedness Of Characteristic Evolution In Bondi Coordinates, Maria Babiuc-Hamilton, Jeff Winicour
Well-Posedness Of Characteristic Evolution In Bondi Coordinates, Maria Babiuc-Hamilton, Jeff Winicour
Maria C. Babiuc-Hamilton
Gravitational waves carry information about their source, and their detection will uncover facets of our universe, otherwise invisible. Recently, we made publicly available a waveform computation tool, the PITT code, as part of the Einstein Toolkit open software for relativistic astrophysics. The code implements the “characteristic method,” which computes the gravitational waves infinitely far from their source in terms of compactified light cones. We proved that our code produces waveforms that satisfy the demands of next generation detectors. However, the main problem is that the well-posedness of the Einstein equations in characteristic formulation is not proven. Here we present our …
High Gravitational Waveform Accuracy At Null Infinity, Maria Babiuc-Hamilton
High Gravitational Waveform Accuracy At Null Infinity, Maria Babiuc-Hamilton
Maria C. Babiuc-Hamilton
The aim of Cauchy-characteristic extraction is to provide a standardized waveform extraction tool for the numerical relativity community. The new extraction tool contains major improvements and corrections to previous versions and displays convergence. The error introduced by CCE satisfies the time domain criteria required for advanced LIGO data analysis. The importance of accurate waveforms to the gravitational wave astronomy has created an urgency for tools like CCE. The source code has been released to the public and is available as part of the Einstein Toolkit. We welcome applications to a variety of generic Cauchy codes implementing Einstein Equations of General …
Using Radial Basis Functions To Interpolate Along Single-Null Characteristics, Maria Babiuc-Hamilton, Clyde E. Meador
Using Radial Basis Functions To Interpolate Along Single-Null Characteristics, Maria Babiuc-Hamilton, Clyde E. Meador
Maria C. Babiuc-Hamilton
The Cauchy-Characteristic Extraction (CCE) technique is the most precise method available for the computation of the gravitational waves obtained from numerical simulations of binary black hole mergers. This technique utilizes the characteristic evolution to extend the simulation to null infinity, where the waveform is computed in inertial coordinates. Although we recently made CCE publicly available to the numerical relativity community, there is still room for improvement, and the most important is enhancing the overall accuracy of the code, by upgrading the numerical methods used for interpolation and differentiation. One of the most promising ways is to use the Radial Basis …