Engines Behind Transients

Theoretical Astrophysics makes headlines in neutron star mergers

Recent work by Christopher Fryer et al. (2015) was recently featured in American Astronomical Society research highlights publication NOVA.

Fryer and collaborators explored the question: what is the final fate of merged neutron stars? The challenge in constructing an answer lies with large uncertainties in the nuclear equation of state.

Fryer and collaborators combined results of particle neutron star merger calculations with a selection of nuclear equations of state, coupled with population synthesis models. The probability that the merger remnant will either directly collapse, collapse with a ~0.1 second delay, or form a larger neutron star is directly dependent on the maximum neutron star mass which can be supported by a given equation of state. This study has ramifications on the frequency of Gamma Ray Bursts (GRBs) which would only rarely take place if the final remnant forms a stable neutron star.

The fraction of mergers that produce Black Holes (BHs) and neutron stars as a function of the maximum neutron star mass allowed by the equation of state is plotted at right. Lines labeled "BHAD" are mergers that produce BHs (with different initial conditions, see Fryer et al. 2015) while lines labeled NS are those that produce NSs.

Kilonova Summer School application deadline extended

This summer, astrophysicists at Los Alamos will join computer scientists in Applied Computer Science (CCS-7) to host approximately 6 graduate students with backgrounds ranging from computer science to physics in a 10-week summer school to model kilonovae, electromagnetic signals from double neutron star mergers from r-process decay in dynamical ejecta.

Applying students should be enrolled in a Ph.D. program and be available from mid-May to mid-September. The summer school represents a unique, collaborative experience with a generous stipend.

Application deadlines have been extended to Feb 26, 2016.