Emitted spectra from a nonmagnetic hydrogen
atmosphere of a neutron star.
NOTE: This model is now in the Xspec release and this page is superceded by the Xspec manual
The 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 A&A 573, 53.
The fitting parameters of the model are listed below:
par1 = Effective temperature T (MK)
par2 = Neutron star mass M (M_sol)
par3 = Neutron star radius R (km)
par4 = Normalization K = A/(d_10kpc)^2
where d_10kpc is the distance to the source in units of 10 kpc and A
characterizes the fraction of the star surface emitting the
radiation (A=1 corresponds to the case when the radiation is emitted from the
entire surface).
To use the model do the following steps:
1) extract hatm.tar.gz, which
will create a directory named "hatm" containing all necessary
files. To compile and to use the model, a writing access to
the directory is necessary!
2) to compile the model, launch XSPEC 12 and execute the following command
XSPEC12> initpackage mypackage model.dat /full-path-to-hatm/hatm/
3) load the compiled model package with "lmod" command:
XSPEC12> lmod mypackage /full-path-to-hatm/hatm/
4) Copy the directory hatm/hatm_tables to
$HEADAS/../spectral/modelData/
or, alternatively, use the "xset" command of XSPEC to set the
HATM variable to the full path to the directory containing
the "hatm_tables" subdirectory:
XSPEC12> xset HATM /full-path-to/hatm/
(Note: /full-path-to/hatm/ should *not* include the "hatm_tables" itself).
The model is now available under the name "hatm".
Please send any questions and comments to
suleimanov@astro.uni-tuebingen.de or
klochkov@astro.uni-tuebingen.de
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Last modified: Tuesday, 14-Feb-2023 16:41:51 EST
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