The nsmaxg model interpolates from a grid of neutron star (NS) atmosphere spectra to produce a final spectrum that depends on the parameters listed below. Atmosphere spectra are obtained using the latest equation of state and opacity results for a partially ionized, strongly magnetized hydrogen or mid-Z element plasma. Models are constructed by solving the coupled radiative transfer equations for the two photon polarization modes in a magnetized medium, and the atmosphere is in radiative and hydrostatic equilibrium. Atmosphere models mainly depend on the surface effective temperature T_{eff} and magnetic field strength B and inclination Θ_{B}; there is also a dependence on the surface gravity g=(1+z_{g})GM/R^{2}, where 1+z_{g}=(1-2GM/R)^{-1/2} is the gravitational redshift and M and R are the NS mass and radius, respectively.
Two sets of models are available: one set with a single surface B and T_{eff} [some models allow for varying g, in the range log g (cm s^{-2}) = 13.6-15.4] and a set which is constructed with B and T_{eff} varying across the surface according to the magnetic dipole model (θ_{m} is the angle between the direction to the observer and the magnetic axis). Effective temperatures span the range log T_{eff} (K) ≈ 5.5-6.7. Models with single (B,T_{eff}) cover the energy range 0.05-10 keV, while models with (B,T_{eff})-distributions cover the range 0.09-5 keV.
The parameters are:
par1 |
log T_{eff}, surface (unredshifted) effective temperature |
par2 |
M, neutron star gravitation mass (in units of Solar mass) |
par3 |
R, neutron star radius (in km) |
par4 |
d, distance to neutron star (in kpc) |
par5 |
Switch indicating model to use |
norm |
1, normalization (though not strictly correct, can be varied to change the size of the emission region, (R_{em}/R)^{2}) |
The models available by setting par5 are:
Switch |
Element |
B(10^{12} G) |
Θ_{B} |
θ_{m} |
log g (cm/s^{2}) |
log T_{eff} |
E (keV) |
1000 |
H |
0.01 |
0 |
N/A |
2.4 |
5.5 - 6.7 |
0.05 - 10 |
1060 |
H |
0.04 |
0 |
N/A |
2.4 |
5.5 - 6.7 |
0.05 - 10 |
1085 |
H |
0.07 |
0 |
N/A |
2.4 |
5.5 - 6.7 |
0.05 - 10 |
1100 |
H |
0.1 |
0 |
N/A |
2.4 |
5.5 - 6.7 |
0.05 - 10 |
1200 |
H |
1.0 |
0 |
N/A |
0.4 - 2.5 |
5.5 - 6.7 |
0.05 - 10 |
1230 |
H |
2.0 |
0 |
N/A |
2.4 |
5.5 - 6.8 |
0.05 - 10 |
1260 |
H |
4.0 |
0 |
N/A |
2.4 |
5.5 - 6.8 |
0.05 - 10 |
1280 |
H |
7.0 |
0 |
N/A |
2.4 |
5.5 - 6.8 |
0.05 - 10 |
1300 |
H |
10.0 |
0 |
N/A |
0.4 - 2.5 |
5.5 - 6.7 |
0.05 - 10 |
1330 |
H |
20.0 |
0 |
N/A |
2.4 |
5.6 - 6.8 |
0.05 - 10 |
1350 |
H |
30.0 |
0 |
N/A |
2.4 |
5.7 - 6.8 |
0.05 - 10 |
1211 |
H |
1.26 |
0 |
N/A |
1.6 |
5.5 - 6.8 |
0.05 - 10 |
1281 |
H |
7.0 |
0 |
N/A |
1.6 |
5.5 - 6.8 |
0.05 - 10 |
12006 |
C |
1.0 |
0 |
N/A |
2.4 |
5.8 - 6.9 |
0.05 - 10 |
13006 |
C |
10.0 |
0 |
N/A |
2.4 |
5.8 - 6.9 |
0.05 - 10 |
12008 |
O |
1.0 |
0 |
N/A |
2.4 |
5.8 - 6.9 |
0.05 - 10 |
13008 |
O |
10.0 |
0 |
N/A |
2.4 |
5.8 - 6.9 |
0.05 - 10 |
12010 |
Ne |
1.0 |
0 |
N/A |
2.4 |
5.8 - 6.9 |
0.05 - 10 |
13010 |
Ne |
10.0 |
0 |
N/A |
2.4 |
5.8 - 6.9 |
0.05 - 10 |
123100 |
H |
1.0 - 1.82 |
0-90 |
0 |
1.6 |
5.5 - 6.8 |
0.09 - 5 |
123190 |
H |
1.0 - 1.82 |
0-90 |
90 |
1.6 |
5.5 - 6.8 |
0.09 - 5 |
130100 |
H |
5.5 - 10.0 |
0-90 |
0 |
1.6 |
5.5 - 6.8 |
0.09 - 5 |
130190 |
H |
5.5 - 10.0 |
0-90 |
90 |
1.6 |
5.5 - 6.8 |
0.09 - 5 |
If you publish results obtained using nsmaxg, please reference Ho, W.C.G., Potekhin, A.Y., & Chabrier, G. (2008, ApJS, 178, 102) and also Mori, K. & Ho, W.C.G. (2007, MNRAS, 377, 905) if using mid-Z models. See Ho, W.C.G. (2014, Proc. of IAUS 302, submitted) for discussion of nsmaxg and nsmax.