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##

hatm: Nonmagnetic hydrogen atmosphere of a neutron star

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). |

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