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nsmax: Neutron Star Magnetic Atmosphere

This model has been superseded by nsmaxg.

This model interpolates from a grid of neutron star (NS) atmosphere spectra to produce a final spectrum that depends on the parameters listed below. The 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. The 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. The atmosphere models mainly depend on the surface effective temperature $T_{eff}$ and magnetic field strength $B$ and inclination $\Theta_B$; there is also a dependence on the surface gravity $g = (1+z_g)GM/R^2$, where $1+z_g = \sqrt{1-2GM/R}$ is the gravitational redshift and $M$ and $R$ are the NS mass and radius, respectively.

Two sets of models are given: one set with a single surface $B$ and $T_{eff}$ and a set which is constructed with $B$ and $T_{eff}$ varying across the surface according to the magnetic dipole model (for the latter, $\theta_m$ is the angle between the direction to the observer and the magnetic axis). The effective temperatures span the range $\log T_{eff} = 5.5 - 6.8$ for hydrogen and $\log T_{eff} = 5.8
- 6.9$ for mid-Z elements. The models with single ($B$,$T_{eff}$) cover the energy range 0.05-10 keV, while the models with ($B$,$T_{eff}$)-distributions cover the range 0.09-5 keV.

par1 $\log T_{eff}$, surface (unredshifted) effective temperature
par2 $1 + z_g$, gravitational redshift
par3 switch indicating model to use
norm $A = (R_{em}/d)^2$, normalization, where $R_{em}$ is the size (in km) of the emission region and $d$ is the distance (kpc) to the object Note: A is added automatically by XSPEC.

The models available by setting par3 are:

Switch Element $B$($10^{12}$ G) $\Theta_B$ $\theta_m$ $\log
g$ (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 nsmax, 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 the mid-Z models. See Ho, W.C.G. (2014, Proc. of IAUS 302, submitted) for discussion of nsmaxg and nsmax.


next up previous contents
Next: nsmaxg: Neutron Star with Up: Additive Model Components Previous: nsatmos: NS Hydrogen Atmosphere