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 and magnetic field strength and inclination ; there is also a dependence on the surface gravity , where is the gravitational redshift and and are the NS mass and radius, respectively.
Two sets of models are available: one set with a single surface and [some models allow for varying , in the range (cm/s) = 13.6-15.4] and a set which is constructed with and varying across the surface according to the magnetic dipole model ( is the angle between the direction to the observer and the magnetic axis). Effective temperatures span the range = 5.5-6.8. Models with single (,) cover the energy range 0.05-10 keV, while models with (,)-distributions cover the range 0.09-5 keV.
par1 | , surface (unredshifted) effective temperature |
par2 | , neutron star gravitational mass |
par3 | , neutron star radius |
par4 | , distance to neutron star |
par5 | switch indicating model to use |
norm | 1, normalization (though not strictly correct, can be varied to change the size of the emission region, () |
The models available by setting par5 are:
Switch | Element | ( G) | (cm/s) | (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 - 6.8 | 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 - 6.8 | 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 nsmax, please reference Ho, Potekhin & Chabrier (2008 and also Mori & Ho (2007 if using the mid-Z models. See Ho (2014) for discussion of nsmaxg and nsmax.