[SN, SNR, and Isolated NS -- Oral ]
A Carbon Atmosphere for the Cassiopeia A Neutron Star
Craig Heinke, University of Alberta
Wynn Ho (University of Southampton)
The nature of the central compact objects in supernova remnants,
showing thermal spectra but no radio pulsations, is a major mystery of
the Chandra era. The youngest known CCO in Cassiopeia A is perhaps the
most mysterious, as spectral fits with single-component models have
given emitting areas too small for neutron star radii, while a hot spot
should produce pulsations that have not yet been detected. We have
produced a variety of light-element atmosphere models for neutron stars,
and found that only unmagnetized carbon atmospheres provide both acceptable
fits to the Cas A CCO spectrum (T~1.5e6 K, R~12 km) and radius constraints
consistent with modern NS models. Our result has ramifications for the
evolution of NS surfaces, NS thermal evolution, and constraints on NS
interior structure.