Self-gravity can be included either through the assumption of a GM/r potential or through a solution of Poisson's equation using one of three linear solver packages (conjugate gradient, multigrid, and FFT) provided for that purpose.
In addition, so-called 1.5D and 2.5D grids, in which the "half-D'' denotes a symmetry axis along which a constant but nonzero value of velocity or magnetic field is evolved, are supported. The hydrodynamic, MHD, and FLD modules can be used, singly or in concert, in one, two, or three space dimensions. Radiation hydrodynamic simulations are enabled via an implicit flux-limited radiation diffusion (FLD) module. ZEUS-MP is the first publicly available ZEUS code to allow the advection of multiple chemical (or nuclear) species. This MHD module is shown to compare quite favorably to the TVD scheme described by Ryu et al. ZEUS-MP offers an MHD algorithm that is better suited for multidimensional flows than the ZEUS-2D module by virtue of modifications to the method of characteristics scheme first suggested by Hawley & Stone. ZEUS-MP is a multiphysics, massively parallel, message-passing implementation of the ZEUS code. Early epochs of galaxy formation z > 5 are found from this new method and results are compared to faint galaxy count interpretations. From fits on SED templates by a $chi^2$-minimization procedure, not only is the photometric redshift derived but also the corresponding spectral type and the formation redshift $z_for$ when stars first formed. The method is applied to the HDF-N sample. The respect of this constraint makes it possible to significantly improve the accuracy of photometric redshifts by decreasing the well-known degeneracy problem.
Moreover we systematically check that the evolution scenarios match observational standard templates of nearby galaxies, implying an age constraint of the stellar population at z=0 for each type. A comparison with results of other models without evolution measures the evolution factor which systematically increases the estimated photometric redshift values by $Delta z$ > 0.2 for z > 1.5. The sensitivity of results to adding near-infrared colors and IGM absorption is analyzed. Dust, extinction and metal effects are coherently taken into account, depending on evolution scenarios. The spectral energy distribution (SED) templates are computed for nine spectral types including starburst, irregular, spiral and elliptical. Photometric redshifts are estimated on the basis of template scenarios with the help of the code ZPEG, an extension of the galaxy evolution model PEGASE.2 and available on the PEGASE web site.
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