**HEAD 2000, November 2000**

*Session 33. Isolated Pulsars*

Display, Thursday, November 9, 2000, 8:00am-6:00pm, Bora Bora Ballroom
[Previous] |
[Session 33] |
[Next]

## [33.16] Atomic calculation for the model atmospheres of cooling neutron stars

*Kaya Mori, C.J. Hailey (Columbia Astrophysics Laboratory)*

Complete modeling of radiative transfer in neutron star
atmospheres is in progress, taking into account the
anisotropy induced by magnetic fields, non-ideal effects and
general relativity. As part of our modeling, we present a
novel atomic calculation method (Multiconfigurational
Effective Potential Method) producing an extensive atomic
data set including energy values and oscillator strengths in
the so-called Landau regime (B > 4.7\times10^{9}Z^{2} G).
Conventional atmosphere models for B=0 are not applicable
to typical field strengths of cooling neutron stars (B ~
10^{12}-10^{13} G), since an atom no longer keeps its
spherical shape so the wave functions must be expanded in
terms of Landau states and a component along the field. The
composition and the configuration of the magnetic field in
the atmosphere are presently unknown, so that atomic data
must be produced for ground and excited states of several
ion states in various magnetic fields. To accomplish this,
we reduced computation time significantly by minimizing the
iterations in the Hartree equation and treating exchange
terms and higher Landau states by perturbation methods.
Inclusion of higher Landau states gives us much more
accurate data for inner orbits unlike other methods based on
the adiabatic approximation. While existing atomic data in
the Landau regime are available only for low Z atoms, our
method can be readily extended to elements up to Fe with
sufficient accuracy to be of relevance for spectroscopic
missions such as XMM-Newton, Chandra and next-generation
X-ray telescopes. Opacity tables based on our atomic data
base will be used to construct model atmospheres by
comparison with observation data from recent X-ray
telescopes.

[Previous] |
[Session 33] |
[Next]