The optical/UV excess of X-ray dim isolated neutron star: I. bremsstrahlung emission from a strangeon star plasma atmosphere

Understand

X-ray dim isolated neutron stars (XDINSs) are characterized by Planckian spectra in X-ray bands, but show optical/ultraviolet(UV) excesses which are the measured photometry exceeding that is extrapolated from X-ray spectra.

• To solve this problem, a radiative model of bremsstrahlung emission from a plasma atmosphere is established in the regime of strangeon star.
• A strangeon star atmosphere could simply be regarded as the upper layer of a normal neutron star.
• This plasma atmosphere, formed and maintained by the ISM-accreted matter due to the so-called strangeness barrier, is supposed to be of two-temperature.