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Model Spectra of Neutron Star Surface Thermal Emission. Department of Physics National Tsing Hua University Lun-Wen Yeh 2004.5.6. Structure of neutron star. P( τ ) ρ ( τ ) T( τ ). Flux = const. Radiation transfer equation. Spectrum. Flux ≠const. Temperature correction.
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Model Spectra of Neutron Star Surface Thermal Emission Department of Physics National Tsing Hua University Lun-Wen Yeh 2004.5.6
Structure of neutron star P(τ) ρ(τ) T(τ) Flux = const Radiation transfer equation Spectrum Flux ≠const Temperature correction
Assumptions • Plane-parallel atmosphere( local model) • Radiative equilibrium( energy transported solely by radiation ) • Equation of state is ideal gas( ionized H) • Neglect conduction and convection • Hydrostatics • No magnetic field • The physical properties independent of time
Structure of NS • Gray atmosphere • Equation of state • Oppenheimer-Volkoff
Structure of NS • Rosseland mean
Radiation transfer equation Spontaneous emission Induced emission Absorption Scattering
Radiation transfer equation Diffusion approimation
Feautrier method Mean intensity like Flux like
Feautrier method Surface normal n
Feautrier method d=2,3,……,D-2,D-1 μ=1,2,……M
Feautrier method d=1 d=2 d=3….. I1 I2 I3 .. .. .. I1 I2 I3 .. .. .. I1 I2 I3 .. .. ..
Test Feautrier method Scattering
Test Feautrier method Scattering and free-free absorption
46~91 4.9% 91~901 4.1% 901~9001 0.39%
46~91 0.29% 91~901 0.17% 901~9001 0.0079%
46~91 0.19% 91~901 0.065% 901~9001 0.0058%
46~91 4.2% 91~901 3.6% 901~9001 0.30%
Future work • Run my program with many directions , and carry out temperature-correction. • Add magnetic filed in local model