Creating neutron star envelope matter on the Omega-60 laser*

Neutron stars (NS) are some of the most extreme objects in the universe containing about 1-2 solar masses in a radius of about 10 km. The dimension and distance to these stars make it very difficult to observe the surface emission, of which there are only a handful of examples in the literature. The typical approach to modeling NSs, for simplicity, is to break them up into a solid crust and a liquid core with the neutron drip density setting the boundary between the two regions. The crust mediates the cooling of the NS, specifically the envelope, and theory predicts a relationship between the surface and boundary temperatures. However, the steepest region of the temperature gradient, where there is a boundary between radiation and degenerate electron dominated heat conduction, lies within the crust and is not observable. Laboratory experiments at these conditions can provide useful spectroscopic data to compare to models and inform the nature of emission from these sorts of plasmas to provide potential signatures for observatories.

 

The work presented here uses capsule implosions on the Omega-60 laser to create conditions relevant to boundary between radiation and degenerate electron heat conduction in NS envelopes. Simulations suggest a thin mid-Z metal layer on the interior surface of the capsule reaches extreme densities and temperatures of several 100s g/cc and over 1 keV. Filtered self-emission images show the evolution of the capsule metal and emission spectroscopy provide information on the conditions in the imploded metal and radiation transport.