Uncovering the quark-gluon plasma

Merging Holographic Neutron Stars (accompanying 1908.03213)

This page contains extra information on the paper linked above, where we simulated the merger of neutron stars with a (partially) holographic equation of state and computed the resulting gravitational wave spectrum. At the bottom we give some useful references.

A movie of a 1.3 solar mass merger

We show the merger of two neutron stars of 1.3 solar masses. They might form a black hole after some time, but not in the 40ms we managed to simulate (this cost about 5 days using 96 CPUs on the Cartesius supercomputer..). The gravitational wave signal of the final state is characteristic for the poorly understood equation of state of neutron star matter and hence very interesting to observe in i.e. the LIGO/VIRGO gravitational wave detector.

A movie of a 1.4 solar mass merger

We show the merger of two neutron stars of 1.4 solar masses. They first settle to a hyper-massive neutron star, which after about 10ms collapses to black hole. This 10ms gives a very characteristic gravitational wave signal and hence is extremely interesting to observe to learn more about the nature of neutron stars.

A movie of a 1.5 solar mass merger:

We show the merger of two neutron stars of 1.5 solar masses. They quickly form a black hole, which is perhaps a bit unfortunate, since this means the gravitational wave spectrum (as can be observed by the LIGO observatory) is rather featureless.

Useful references

All simulations were performed using the publicly available Einstein Toolkit: https://einsteintoolkit.org

We used the special WhiskyTHC version of the Toolkit, kindly made available by David Radice here: https://www.astro.princeton.edu/~dradice/whiskythc.html

Initial data was generated using the LORENE code: https://lorene.obspm.fr

Also useful information can be found on the website of Roberto De Pietri: http://www.fis.unipr.it/gravity/Research/RealBNS.html

From the same group comes the extremely useful PhD thesis of Francesco Maione (available here)

We plan to make our parameter and computational notebooks available here, or upon request.