Release History

July 23, 2008: sphray-0.9 patched

• the code has now been documented using doxygen (see here ).
• a new ionization solver that is guaranteed to stay bounded between 0.0 and 1.0 has been implemented. It can be used by uncommenting the Makefile flag DuseEuler.
• preliminary support for reading in Gadget snapshots has been added. The input style is now chosen in the Makefile. Two useful options are DSphrayIn and DGadgetPubIn which read the Sphray and Gadget (public version) snapshot formats.

March 04, 2008: sphray-0.9 patched

• the multiple snapshot functionality was improved
• a new ionization solver was implemented based on a backwards differencing method (see Anninos et al. 1997) . The new solver is activated by uncommenting the Makefile macro DuseBDF.

February 27, 2008: sphray-0.9 released

** note that this first release represents a synthesis of codes that previously had seperate functionality and that despite testing there are most likely still minor bugs in the code. If you encounter one please contact me (galtay@andrew.cmu.edu)

Introduction

The Smoothed Particle Hydrodynamics RAYtracer (pronounced "spray") is a Fortran 90 software suite for simulating radiative transfer on precomputed SPH density fields. The code is always under construction, but I keep stable versions here. SPHRAY is open source and you are free to download and modify it under the terms of the latest version of the GNU General Public License

The SPHRAY package was developed at Carnegie Mellon University by Gabriel Altay and Inti Pelupessy. If you are going to use SPHRAY it is highly recommended that you send Gabriel Altay an email (see Feedback section) so that you can be made aware of bug fixes.

Features

• Includes Hydrogen and Helium Ionizations
• Includes temperature dependent radiative transfer
• Supports periodic or vaccuum boundary conditions
• Includes an interactive openGL package (see screenshots )
• Need only a Fortran 90 compiler for basic operation
• Includes a Gadget-2 snapshot converter

Documentation

Doxygen Documentation .

You can download a pdf version of the user's guide for SPHRAY. The user's guide is meant to get a user started but is not meant to be comprehensive.

The NASA ADS link to the code paper. Note: the time scale on which academic papers are updated is much longer than the time scale on which the code is updated. The most recent and relevant information about SPHRAY can be found in these pages and in the user's guide above.

Validation

SPHRAY has been validated against other cosmological radiative transfer codes. Below are links to the results of SPHRAY when applied to the tests outlined in the Radiative Transfer Comparison Project of Iliev et. al. 2006 . Please see that paper for detailed descriptions of the tests.

• RT Comparison Project Test 1
• RT Comparison Project Test 2
• RT Comparison Project Test 3
• RT Comparison Project Test 4

Download

The source code and example density fields can be downloaded at the SPHRAY download page

Feedback

If you have comments, questions, or suggestions regarding SPHRAY, please send me an email (galtay@andrew.cmu.edu).

Publically Available Algorithms Used

Mersenne Twister (M. Matsumoto and T. Nishimura)

SPHRAY needs to generate a very large set of random numbers with good statistical properties. The Mersenne Twister is a very fast random number generator with a period of ( 2¹⁹⁹³⁷-1 ). The code was originally written in C but has been ported to many languages.

ORDERPACK (Michel Olagnon)

The method SPHRAY uses to calculate the intersections of particles and rays does not sort them according to distance from the source, however this is a necessary step. The routines used in SPHRAY are part of a Fortran 90 package called ORDERPACK.