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Full-Text Articles in Physics

Black Holes, Wormholes, And Extra Dimensions, Maria Babiuc-Hamilton Dec 2017

Black Holes, Wormholes, And Extra Dimensions, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

No abstract provided.


New Numerical Code For Black Hole Initial Data, Maria Babiuc-Hamilton Dec 2017

New Numerical Code For Black Hole Initial Data, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

There are no exact solutions of Einstein Equations that describes a bound system radiating gravitational waves. One needs to resort to numerical simulations, or analytical approximation methods. Current methods to constrained initial data exhibit junk radiation and ambiguities about constrained and free data. It was mathematically proved that given the correct initial data, Einstein equation will yield the expected solution.


Undergraduate Research In Gravitational Waves Astronomy At Marshall University, Maria Babiuc-Hamilton Dec 2017

Undergraduate Research In Gravitational Waves Astronomy At Marshall University, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

This is a presentation of undergraduate student research into gravitational waves at Marshall University.


Dawn Of Gravitational Wave Astronomy, Maria Babiuc-Hamilton Dec 2017

Dawn Of Gravitational Wave Astronomy, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

This presentation chronicles the discovery of gravity waves.


Learning To Teach And Teaching To Learn, Maria Babiuc-Hamilton Dec 2017

Learning To Teach And Teaching To Learn, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

New studies show that students do better in science classes that are taught interactively. We compare two different pedagogical approaches in teaching introductory physics: the lecture-based method, the active learning laboratories. We present the data on student performance on exams, homework, lab activities and tests, from 126 students taking the 200-level introductory physics courses at Marshall University, in Huntington, WV. We discuss the efficiency of each method in fostering the success of students in the introductory physics courses. We find that subtle differentiations can be implicitly detected in students’ exam grades, homework, participation, and choice of major.


The First Open-Source General Relativistic Force-Free Electrodynamics Code, Maria Babiuc-Hamilton, Zach Etienne, Mew-Bing Wan Aug 2017

The First Open-Source General Relativistic Force-Free Electrodynamics Code, Maria Babiuc-Hamilton, Zach Etienne, Mew-Bing Wan

Maria C. Babiuc-Hamilton

We are writing the first open-source, general relativistic force-free electrodynamics code: GiRaFFE. The goal is to numerically simulate neutron star and black hole magnetospheres. The GiRaFFE is alive! It has passed a number of 1D code validation tests, and 3D tests are underway. We plan to release the code and test suite initial data routines open-source to the community.


Towards A Standardized Characteristic Extraction Tool, Maria Babiuc-Hamilton Aug 2017

Towards A Standardized Characteristic Extraction Tool, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Knowing the precise details of the gravitational wave signature obtained from numerical simulations of binary black hole mergers is a key requirement for meaningful detection and scientific interpretation of the data. However, the waveforms are not easy to be accurately computed. The importance of this problem to the future of gravitational wave astronomy is well recognized. Cauchy-Characteristic Extraction (CCE) is the most precise and refined extraction method available. The CCE technique connects the strong-field Cauchy evolution of the spacetime near the merger to the characteristic evolution to future null infinity where the waveform is extracted in an unambiguous way. Recently, …


Simulating Magnetospheres With Numerical Relativity: The Giraffe Code, Maria Babiuc-Hamilton Aug 2017

Simulating Magnetospheres With Numerical Relativity: The Giraffe Code, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Numerical Relativity is successful in the simulation of black holes and gravitational waves. In recent years, teams have tackled the problem of the interaction of gravitational and electromagnetic waves. We developed a new code for the numerical simulation of neutron and black hole magnetospheres, using the FFE formalism. We tested the performance of the new code named GiRaFFE, in 1D and 3D test suits. We will study magnetospheres, focusing on jets by the Blandford -Znajek mechanism.


Cauchy-Characteristic Patching With Improved Accuracy, Maria Babiuc-Hamilton Aug 2017

Cauchy-Characteristic Patching With Improved Accuracy, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Cauchy-characteristic extractions (CCE) avoids the errors due to extraction at finite worldtube. The Cauchy and the characteristic approaches have complementary strengths and weaknesses. Unification of the two methods is a promising way of combining the strengths of both formalisms.


Towards A Fully Nonlinear Cauchy Characteristic Extraction, Maria Babiuc-Hamilton Aug 2017

Towards A Fully Nonlinear Cauchy Characteristic Extraction, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

The artificial finite outer boundary present in Cauchy codes introduce two sources of error: The outer boundary condition and waveform extraction at an inner worldtube. The problem of proper boundary condition for a radiating system can be solved only by extension to Ι+ (conformal compactification). Cauchy Characteristic Extraction (CCE) offers a means to avoid these errors.


Towards Improved Accuracy Of Gravitational Waves Extraction, Maria Babiuc-Hamilton Aug 2017

Towards Improved Accuracy Of Gravitational Waves Extraction, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Results in developing two new methods to improve the accuracy of waveform extraction using characteristic evolution. Numerical method: circular boundaries, with angular dissipation in the characteristic code. Geometric method: computation of Weyl tensor component Y4 at null infinity, in a conformally compactified treatment. Comparison and calibration in tests problems based upon linearized waves.


Gravitational & Electromagnetic Waves On The Null Cone, Maria Babiuc-Hamilton Aug 2017

Gravitational & Electromagnetic Waves On The Null Cone, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Bondi (1962) proved mathematically the existence of gravitational waves at null infinity. He found an exact solution of Einstein equations. Within this metric, he calculated the loss of mass due to the emission of gravitational waves. The mas of a system is constant if and only if there is no news. If there is news, the mass decreases as long as there are news.


Testing A Model For The Well-Posedness Of The Cauchy-Characteristic Problem In Bondi Coordinates, Maria Babiuc-Hamilton, Jeff Winicour Aug 2017

Testing A Model For The Well-Posedness Of The Cauchy-Characteristic Problem In Bondi Coordinates, Maria Babiuc-Hamilton, Jeff Winicour

Maria C. Babiuc-Hamilton

Gravity waves reveal colliding black holes, galaxies, the birth of a black hole in a supernova and the growth pains of our universe. Gravitational waves are unambiguous measured only at future null infinity.


Steps Towards A Nonlinear Cauchy-Characteristic Code Patching, Maria Babiuc-Hamilton Jul 2017

Steps Towards A Nonlinear Cauchy-Characteristic Code Patching, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Cauchy-characteristic extractions (CCE) avoids the errors due to extraction at finite worldtube. The Cauchy and the characteristic approaches have complementary strengths and weaknesses. Unification of the two methods is a promising way of combining the strengths of both formalisms.


Characteristics Of Gravitational And Electromagnetic Radiation, Maria Babiuc-Hamilton Jul 2017

Characteristics Of Gravitational And Electromagnetic Radiation, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Gravitational waves from the early universe are detectable, but detection is difficult. The strain is extremely small of magnitude 10-3 the width of a proton. There are detection and computational challenges.


An Analysis Of The Gravitational Waves Null Memory, Maria Babiuc-Hamilton Jul 2017

An Analysis Of The Gravitational Waves Null Memory, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Gravitational wave astronomy sees (hears) gravitational waves by observing the phenomena of gravitational and electromagnetic memory, and the formation of trapped surfaces and horizons.


Tools For Gravitational Wave Astronomy, Maria Babiuc-Hamilton Jul 2017

Tools For Gravitational Wave Astronomy, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Gravitational waves have been confirmed. Tools are available for their study, including the Einstein Toolkit, SimulationTools and the SXS Gravitational Waveform Database.


Gravity & Electromagnetism On The Null Cone, Maria Babiuc-Hamilton Jul 2017

Gravity & Electromagnetism On The Null Cone, Maria Babiuc-Hamilton

Maria C. Babiuc-Hamilton

Gravitational and electromagnetic radiation travel along light rays, which are principal null directions in space-time. They are characteristic surfaces of Einstein and Maxwell equations. In characteristic coordinates, the field is described by ordinary differential equations.


A New Algorithm For The Numerical Computation Of Gravitational Waves, Maria Babiuc-Hamilton, Jeff Winicour Jul 2017

A New Algorithm For The Numerical Computation Of Gravitational Waves, Maria Babiuc-Hamilton, Jeff Winicour

Maria C. Babiuc-Hamilton

With gravitational waves, Gravitational Wave Astronomy can “see” colliding back holes and galaxies, the birth of a black hole in a supernova, the growth pains of our universe and the structure of spacetime.


A Hyperbolic Solver For Black Hole Initial Data In Numerical Relativity, Maria Babiuc-Hamilton, Jeff Winicour, I. Racz Jul 2017

A Hyperbolic Solver For Black Hole Initial Data In Numerical Relativity, Maria Babiuc-Hamilton, Jeff Winicour, I. Racz

Maria C. Babiuc-Hamilton

Initial data in numerical relativity. The constraints are formulated as elliptic equations, parabolic equations and strongly hyperbolic equations. This presentation is about a different approach to initial data for black holes, the strongly hyperbolic method.