Tales From The Haystack: Isolated Neutron Stars and Low-Mass White Dwarfs

I will discuss two programs I am leading that use multiwavelength observational data to identify new neutron stars. Determining neutron star properties observationally is our best hope of constraining the equation of state of matter at extreme densities. Using correlations of the optical Sloan Digital Sky Survey (SDSS) with the X-ray ROSAT All-Sky Survey, I identified a dozen new candidate isolated neutron stars (only seven are now known), and I will present the current status of this work. Like neutron stars, white dwarfs are by-products of stellar death, and SDSS discovered a small number with very low masses. These rare white dwarfs are expected to form in binary systems, potentially with neutron star companions. I will describe follow-up radio, optical, and X-ray observations to determine the nature of the low-mass white dwarfs' companions. Both of these efforts may eventually allow us to add to the few measurements we have of neutron star masses and radii, thereby informing theoretical predictions for the neutron star equation of state.