^{Physics and Astronomy}

_{Gravitational wave sources on a computer}

**Example Project: Gravitational wave sources on a computer**

The strong gravitational fields near black holes and neutron stars can be accurately modeled only using general relativity. Neutron stars allow one to study the highest densities in the universe as well as strong gravity. Collisions and mergers of these objects are of great interest to astronomers because of the gravitational waves they produce, the distinctive electromagnetic signals they leave, and the role they play in the creation of heavy elements. Dynamic events involving strong gravity systems, especially mergers and collapses/black hole formation, must be modeled on the computer with the tools of numerical relativity [1]. In addition to relativity, fluid dynamics, magnetic fields, and neutrino radiation are crucial in such simulations. The numerical relativity group at WSU uses computer simulations with the Spectral Einstein Code (SpEC) [2] incorporating all these effects to model violent events involving neutron stars.

An REU student could contribute to this work in a couple of ways.

1) Carrying out low-resolution exploratory binary simulations with unexplored initial conditions (masses, spins, equation of state, magnetic field).

2) Carrying out and analyzing tests of the magnetohydrodynamics evolution in the SpEC code

Students will have exposure to several different fields of physics, definitely learning a great deal about relativistic hydrodynamics. They will carry out their own code development projects and gain experience analyzing data from numerical relativity simulations. Depending on the project, they may carry out simulations on high-performance computing clusters themselves.

Students will be expected to have some prior programming experience (no particular language is required, but C/C++ will be most helpful). They should also have background in mathematical physics at the intermediate mechanics / 1st-semester E&M level.

Prof. Matthew Duez has supervised the senior thesis projects of 7 WSU undergraduates. Two of these were literature review projects, and the rest research projects. One of these students was co-author on a PRL [3]. Another student currently working with Prof. Duez is expected to complete her senior thesis this academic year and be a co-author on an upcoming paper.

[1] http://www.black-holes.org/SpEC.html

[2] Numerical Relativity of Compact Binaries in the 21st Century, Duez and Y. Zlochower, Rep. Prog. Phys. 82 (2019) 016902 10.1088/1361-6633/aadb16

[3] Effects of neutron-star dynamic tides on gravitational waveforms within the effective-one-body approach Hinderer et al, Phys. Rev. Lett. 116, 181101 (2016) 10.1103/PhysRevLett.116.181101