Model Spectra of Neutron Star Surface Thermal Emission

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) Radiation transfer equation Flux ≠const Temperature correction Flux = const Spectrum

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 Absorption Scattering Spontaneous emission Induced emission

Radiation transfer equation Diffusion approimation

Feautrier method Mean intensity like Flux like

Feautrier method Surface normal n

Feautrier method

Feautrier method d=2, 3, ……, D-2, D-1 μ=1, 2, ……M

Feautrier method d=1 d=2 d=3…. . I 1 I 1 I 2 I 2 I 3 I 3 . . . .

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