Neutron-Star Optics

Researchers have generally assumed that the spacetime surrounding a neutron star is well approximated by Schwarschild or Kerr to calculate ray tracing because of the high degree of symmetry of these spacetimes.  Psaltis and Jonahannsen present a new algorithm that goes beyond these toy models and use a metric with an arbitrary quadrupole moment.  This requires integrating 2nd-order ODES (rather than the 1st-order in the case of Kerr).  They outline some systems where this technique provides potentially important diagnostics.

 arXiv:1011.4078 [pdf, ps, other]

A Ray-Tracing Algorithm for Spinning Compact Object Spacetimes with Arbitrary Quadrupole Moments. I. Quasi-Kerr Black Holes

Dimitrios Psaltis, Tim Johannsen (Arizona)