Speaker
Description
More than 50 years after the discovery of neutrons stars, their interior composition and structure remain unknown. Because the extreme densities and matter asymmetry in neutron star interiors are out of reach for Earth laboratories, the equation of state of bulk nuclear matter is unknown, and its determination would have implication for astrophysics and nuclear physics. Thankfully, measurements of neutron stars masses and radii are direct probes of the interior of these compact objects, and therefore on the composition and behaviour of dense nuclear matter. Mass measurements have been accessible from radio pulsars in binary systems since the discovery of the Hulse-Taylor pulsar in the 1970s, providing exquisite precisions for neutron stars between $1.2$ and about $2.1$ solar masses. In the past two decades, X-ray observatories have provided some measurements of neutron star radii, but with limited precision in comparison to the mass measurements. However, recently, the results from the NICER Observatory showed the most promising, robust and precise measurements. I will give a quick historical overview of mass and radius measurements, followed by a presentation of the key and recent results from the NICER mission. The talk will finish with a discussion of expected constraints from future observatories.
