Another neighbor Prashanth Jaikumar visiting from Cal State Long Beach highlighted current theoretical and numerical efforts to model neutron stars as quark superconductors.

Prashanth introduced us to the key features of these highly compact remnants of supernova explosions that display many amazing and extreme properties with roughly twice the mass of the sun packed into a diameter of 10 to 15 km. Thus, the density of matter in neutron stars well exceeds the density of matter in atomic nuclei. The star cores exist under such enormous pressures that new phases of matter not seen on earth dominate, as for example superconducting quark matter. Nevertheless, temperatures are relatively low due to cooling throughout the star from neutrino and x-ray radiation. Though composed of quarks, the star matter will therefore likely exhibit features familiar from terrestrial electronic systems including long-range order, ferromagnetism, and gapless superconductivity.

Prashanth detailed how the relatively low temperatures constrain the properties of a quark-based superconductor and define a "periodic-table" of sorts of the star's inner structure. He connected in this way with his overriding goals to predict macroscopic observables, like the star's mass, radius and rotation rate to more subtle signals like neutrino bursts and gravitational waves, from the microscopic description of star matter as a rather exotic material. He mentioned for example that our own neutron-star expert Jocelyn Read predicted recently how gravitational-wave observations would refine star-radius estimates and thus further constrain the distinction between neutron and quark matter.

Prashanth came to campus to visit the members of our gravitational-wave center GWPAC, and hopes to develop a closer collaboration with the center.

Thank you for your visit, Prashanth!