I’ve read an observational paper by Stockton, McGgrath, & Canalizo discussing Extremely Red Objects (EROs) in two quasar fields at z~1.4.

I read a description of the Particle Mesh (PM) method and a code, by Michael Fellhauer, that uses the method.  I’ve also downloaded the (apparently famous) book “Computer Simulation Using Particles” by Hockney & Eastwood which describes the method in more detail.   The general idea is that we can calculate the potential everywhere on a Cartesian mesh using a Green’s function method to solve Poisson’s equation

The first step is to transfer particle-mass data to the mesh in order to approximate the density .  Then the Fourier transform of the density is computed using FFT (requiring the number of mesh elements in each dimension to be a power of two).  Then a fast Fourier transformed Green’s function is multiplied by the transformed RHS of the above equation and the inverse transform is computed to calculate the potential at the mesh points.  Once the potential is known everywhere, finite difference methods can be used to calculate the acceleration of each particle and then the velocities and positions are updated.

The standard PM method assumes that the situation at hand is inherently static and Newtonian gravitation is fully valid.

This entry was posted on Tuesday, September 15th, 2009 at 5:41 pm and is filed under regular update. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.