Description

This model provides the spectra in the X-ray range (0.05-10 keV) emitted from a hydrogen atmosphere of a neutron star. There are three options:

• nonmagnetized (B < 1e8 - 1e9 G) with a uniform surface (effective) temperature in the range of log T_eff(K) = 5.0-7.0 ;
• a field B = 1e12 G with a uniform surface (effective) temperature in the range of log T_eff(K) = 5.5-6.8 ;
• a field B = 1e13 G with a uniform surface (effective) temperature in the range of log T_eff(K) = 5.5-6.8 .

The atmosphere is in radiative and hydrostatic equilibrium; sources of heat are well below the atmosphere. The Comptonization effects significant at T_eff > 3e6 K) are taken into account. The model spectra are provided as seen by a distant observer, with allowance for the GR effects. The user is advised to keep M_ns and R_ns fixed and fit the temperature and the normalization. MagField must be fixed at one of 0, 1e12, or 1e13 G.

The values of the effective temperature and radius as measured by a distant observer ("values at infinity") are

T_eff^Inf = g_r*T_eff

R_ns^Inf = R_ns/g_r

where

g_r=(1-2.952*M_ns/R_ns)^0.5

xsnsa Parameters

If you publish results obtained using this model, please reference Pavlov et al. (1992, MNRAS 253, 193) and Zavlin et al. (1996, A&A 315, 141).

This information is taken from the XSpec User's Guide. Version 11.3.1 of the XSpec models is supplied with CIAO 3.2.