A Solution for the Nonuniqueness Problem of the Spacetime Constraint Equations

I. Cordero-Carrión, P. Cerdá-Durán, H. Dimmelmeier, J. L. Jaramillo, J. Novak, E. Gourgoulhon

The otherwise very successful CFC scheme for approximating the Einstein equations in simulations of compact astrophysical objects fail at very high densities. We have found a reformulation which solves this problem and extends the applicability of CFC to e.g. black hole formation.

Phase-Transition-Induced Collapse of a Rotating Neutron Star to a Hybrid Quark Star

E. B. Abdikamalov, H. Dimmelmeier, L. Rezzolla, J. C. Miller

If rotating neutron stars undergo a phase transition from regular matter to quarks in their core, the subsequent collapse can be a strong source of gravitational waves. We have performed the first-ever general relativistic simulations of this scenario, and find that resonance effects can even enhance the emission of gravitational radiation.

Comparing Full General Relativity with the Conformally Flat Approximation in Rotating Supernova Core Collapse

C.D. Ott, H. Dimmelmeier

For models of rotating stellar cores collapsing to a neutron star with both microphysics and a simple equation of state we have demonstrated that the often used CFC approach is an excellent approximation of full general relativity.
 

Simulations of Rotational Stellar Core Collapse in General Relativity with Microphysics

H. Dimmelmeier, C.D. Ott, H.-T. Janka, A. Marek, I. Hawke, B. Zink, E. Schnetter, and E. Müller

We have performed the first 2D and 3D simulations of rotating stellar core collapse to a neutron star in general relativity with microphysics. We have found that the resulting gravitational wave signals are much more generic than previously anticipated.

Nonlinear Axisymmetric Pulsations of Rotating Relativistic Stars

H. Dimmelmeier, N. Stergioulas, J.A. Font

With the axisymmetric version of the "Mariage des Maillages" code we have for the first time simulated pulsations in uniformly and differentially rotating neutron star models in general relativistic gravity and identified important nonlinear effects. We have also investigated the issue of detectability of gravitational wave emitted by such oscillations.

Exploring the Relativistic Regime with Newtonian Hydrodynamics: An Improved Effective Gravitational Potential

B. Müller, A. Marek, H. Dimmelmeier, H.-T. Janka, E. Müller, R. Buras

We have successfully approximated relativistic effects in simulations of supernova core collapse and by using an effective relativistic potential in an otherwise standard Newtonian hydrodynamic code. With a simple modification of the gravitational potential, such codes can be easily extended into the moderately relativistic regime.

"Mariage des Maillages":
Combining Spectral Methods and Finite Difference Methods
in General Relativistic Hydrodynamics

H. Dimmelmeier, J. Novak, J.A. Font, J.M. Ibáñez, E. Müller

Based on an axisymmetric code used for our previous simulations of general relativistic rotational core collapse we have combined spectral methods and finite difference grid methods in a 3D general relativistic hydrodynamics code.

General relativistic rotational core collapse with improved dynamics and waveforms in CFC+

P. Cerdá-Durán, G. Faye, H. Dimmelmeier J.A. Font, J.M. Ibáñez, E. Müller, G. Schäfer

We have improved the collapse dynamics and gravitational waveforms from the our previous simulations of general relativistic rotational core collapse by extending the mathematical approximation used in that approach to higher orders.

Gravitational Radiation from Relativistic Rotational Core Collapse

H. Dimmelmeier, J.A. Font, E. Müller

We have succeeded for the first time to simulate the collapse of a rotating stellar core to a neutron star including the effects of general relativity, making a major step forward towards realistic predictions of gravitational wave signals.