This model provides the spectra emitted from a nonmagnetic hydrogen atmosphere of a neutron star. The model spectra in a 0 - 20 keV range of (unredshifted) photon energy are computed on a grid of surface gravity accelerations log(g)=13.7 - 14.9 (in cgs units) and effective temperatures T = 0.5 - 10 MK. For a given set of the fitting parameters, the surface gravity g and the gravitational redshift z are derived from the mass M and radius R of the star. The trial spectra are computed using a linear interpolation between the nearest model spectra on the T-log(g) grid, and the boundaries of the energy bins and the number of photons in each bin are divided by (1+z). The details of the model can be found in Suleimanov et al. (2016; A&A, submitted) and Klochkov et al. (2015).
The directory used for the files required by this model can be changed by using the xset command to set HATM.
The parameters are:
|par1||Effective temperature T (MK)|
|par2||Neutron star mass M (M)|
|par3||Neutron star radius R (km)|
|par4||Normalization K = A/(dkpc) where dkpc is the distance to the source in units of 10 kpc and A characterizes the fraction of the surface emitting the radiation (A=1 corresponds to the case when the radiation is emitted from the entire surface).|