NS Magnetic Atmosphere Model
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 Teff and magnetic field strength B and inclination ΘB; there is also a dependence on the surface gravity g=(1+zg)GM/R2, where 1+zg=(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 given: one set with a single surface B and Teff [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 Teff varying across the surface according to the magnetic dipole model (θm is the angle between the direction to the observer and the magnetic axis). Effective temperatures span the range log Teff (K) ≈ 5.5-6.7. Models with single (B,Teff) cover the energy range 0.05-10 keV, while models with (B,Teff)-distributions cover the range 0.09-5 keV. See here for a list of models. (Note that the spectral tables can easily be made compatible with other XSPEC NS fitting models.)
The model parameters are :
Please send your comments/questions to Wynn Ho (firstname.lastname@example.org). 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.
Keith Arnaud, X-ray Astrophysics Lab., NASA/Goddard Space Flight Center
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Last modified: Monday, 12-Sep-2013 16:16:00 EDT