Neutron stars are the collapsed end states for most massive stars. They provide a testing ground for physics under extreme conditions unrealizable on the Earth. The study of thermal radiation from isolated neutron stars (including radio pulsars, radio-quiet neutron stars and magnetically-powered pulsing neutron stars) can provide important information on the interior physics, magnetic fields, surface composition and other properties of neutron stars. The new generation of X-ray telescopes, especially, are bringing great promise to such study, and high-quality data are already coming online. Understanding the properties of matter and radiation in strong magnetic fields is essential for the proper interpretation of the current and future observations of neutron star surface emission. The principle investigator (PI) of this project is continuing to systematically study the surface layers and the radiation spectra of strongly magnetized neutron stars in a series of related investigation. The PI is studying the electronic and radiative properties of matter in strong magnetic fields, the propagation of radiation in the superstrong magnetic field regime, atmosphere models to examine radiation spectra from magnetic neutron stars for comparisons with observations, and certain phase transitions of condensed metallic hydrogen and helium and their radiation signatures, relevant to cool neutron stars with superstrong magnetic fields.
Broader Impacts. The research project includes training and support for graduate students (including a woman student), and it involves talented undergraduate students as well. The subject of "Astrophysics under Extreme Conditions" has a broad appeal to undergraduate students (even nonscience students), and the PI gives many presentations on this subject to undergraduates and the general public. There is active collaboration and interdisciplinary research with solid state physicists at Cornell, and plasma physicists and astrophysicists in Russia and France. The PI also provides theoretical models to observational groups. Discussion is underway with scientists at the Laboratory for Laser Energetics to explore laboratory astrophysics research using intense lasers.
