Numerous physical problems require a detailed understanding of the radiative transfer of photons into different environments, ranging from intergalactic and interstellar medium to stellar or planetary atmospheres. The solution of the complete radiative transfer equation is presently beyond our capabilities, but several groups are  attacking the problem by using different numerical schemes and approximations (i.e. ray-tracing,  Monte Carlo methods, local depth approximation...). At this stage, it appears worthwhile to make a comparison between these different approaches.

At the conference  The Physics of Galaxy Formation, Tsukuba, Japan, July 3-7 2000, Andrea Ferrara, in his concluding remarks, proposed to apply the available codes to a commonly defined radiative transfer problem . In honor of Tsukuba, guest city of the conference, this initiative has been called the TsuCube. During the workshop that will be hosted by CITA we plan to finalize the comparison between different codes.

Below you can find the necessary instruction for the proposed tests, while in the paper you can find more details.
Note that the codes that do not solve He chemistry should perform the Tests where He is included (Test 0 and Test 2) setting the initial H density to the total density (e.g. in Test 0 n_H=1 cm^-3).

The basic physics

- Test 0: rates and evolution of a single zone

Pure radiative transfer tests

- Test 1: pure-hydrogen isothermal HII region expansion

- Test 2: HII region expansion: the temperature state

- Test 3: I-front trapping in a dense clump and the formation of a shadow

- Test 4: Multiple sources in a cosmological density field

Radiative hydrodynamics tests

- Test 5: Classical HII region expansion

- Test 6: HII region expansion in 1/r² density profile

- Test 7: Photoevaporation of a dense clump


Submission of tests results

To upload your files (we recommend to COMPRESS them) please go to:
www.cita.utoronto.ca/~iliev/workshop/form.html
which provides a form for file submission. Since all files you submit would go to the same directory, please follow the following naming conventions. The files should be called
Tnumber_grid_name.dat
and
Tnumber_front_name.dat
for the 3-D and the 1-D data respectively. Here, "name" is the name of your group or your code and "number" is the test number (e.g. T2_grid_iliev.dat).
Please note that the 1-D I-front positions and velocities for each test should be submitted as one file, in 3 columns (t,x_I,v_I), with units [Myr,kpc,km/s]. The x_I should be the linearly-interpolated I_front position inside the cell and v_I is finite-differenced from x_I.
For what concerns the format, all files should be provided as ASCII free-format single-precision (Real*4) files, i.e. the 3-D data should be readable using:
do i=1,128
  do j=1,128
   do k=1,128
    read(*,*,*) all requested quantities in the order listed
   end do
  end do
end do


Participants

The codes/groups that have so far joined the TsuCube are:
1.   CRASH: Cosmological RAdiative transfer Scheme for Hydrodynamics (A. Maselli, A. Ferrara & B. Ciardi)
2.   C²-Ray: Photon-conserving transport of ionizing radiation (G. Mellema, I. Iliev, P. Shapiro & M. Alvarez)
3.   OTVET: Optically Thin Variable Eddington Tensor (N. Gnedin & T. Abel)
4.   ART: Authentic Radiative Transfer with Discretized Long Beams (T. Nakamoto, H. Susa, K. Hiroi & M. Umemura)
5.   RSPH: SPH coupled with radiative transfer (H. Susa & M. Umemura)
6.   FLASH-HC: Hybrid Characteristics: 3D radiative transfer for parallelized AMR hydrodynamics codes (E.-J. Rijkhorst, T. Plewa, A. Dubey & G. Mellema)
7.   SimpleX: radiative transfer on unconstructed grids (J. Ritzerveld, V. Icke & E.-J. Rijkhorst)
8.   ZEUS-MP with radiative transfer (D. Whalen & M. Norman)
9.   FTTE: Fully Threaded Transport Engine (A. Razoumov)
10.   IFT: Ionization Front Tracking (M. Alvarez & P. Shapiro)
11.   CORAL (I. Iliev, A. Raga, G. Mellema, P. Shapiro)