Updates:
- 2017/05/18: graytrix_v2.2.f released (some bugs in graytrix_v2.1.f were fixed).
What is GRayTrix ?
Fortran programs for full-sky gravitational lensing numerical
simulation, developed by Takashi Hamana, Masato Shirasaki and Ryuichi Takahashi.
How GRayTrix works ?
- Reading Nbody particle position data (Gadger2 snapshot file format is assumed)
and taking particles located in a given shell, projecting them onto a sphere to
produce a surface mass density, and calculating two-dimensional
gravitational potential and its 1st and 2nd derivatives via the
spherical harmonics transformation using Healpix library.
{filename}.psis file is outputed.
- Reading potential data ({filename}.psis) that
generated by the above step, and tracing the light ray trajectory using
by the multiple-plane gravitational lensing algorithm.
A virtual observer is located at the centre of the nested simulation
boxes. Rays are traced backwards from the observer point with the
initial ray directions being set on HEALPIX pixel centres.
One can choose the source-plane at an arbitrary redshift.
The source position on the source-plane and the magnification matrix for
each rays are calculated and outputed ({filename}.pos.dat and
{filename}.mag.dat, respectively).
Fortran programs:
- gadget2psis_v1.1.f : Calculating two-dimensional
gravitational potential and its 1st and 2nd derivatives from Nbody
particle data.
Required memory size is 2.2Gb for nres=12, and 4 times more for nres=13 and so on.
See gadget2psis_v1.1.readme for
compilation and usage.
Latest update: 2016-03-09
- graytrix_v2.2.f : Reading potential
data ({filename}.psis) that is generated by the above step, and tracing
the light ray trajectory using by the multiple-plane gravitational lensing algorithm.
The source position on the source-plane and the magnification matrix for
each rays are calculated and outputed ({filename}.pos.dat and
{filename}.mag.dat, respectively).
Required memory size is 47Gb for nres=12, and 4 times more for nres=13
and so on.
See graytrix_v2.2.readme
and graytrix_v2.2.in for
compilation and usage.
MPI version of graytrix_v2.0.f is available upon request.
Latest update: 2017-05-18
- dat2fits.f : Converting data format of {filename}.mag.dat from
FORTRAN binary to Healpix fits.
Latest update: 2016-04-07
- skyhalo_v3.3.f : Locating halos in the same full-sky light-cone
space as the ray-tracing simulation with taking into account the
lensing deflection. Fortran program available upon request.
Code papers:
If you use Graytrix for scientific work, we kindly ask you to reference
the following papers in which Graytrix algorithm is described:
- Cosmological constraints from Subaru weak lensing cluster counts
Takashi Hamana, Junya Sakurai, Michitaro Koike, Lance Miller
PASJ, 67, 34 (2015)
Reprint (link to
ADS)
- Probing cosmology with weak lensing
selected clusters I: Halo approach and all-sky simulations
Masato Shirasaki, Takashi Hamana, Naoki Yoshida
MNRAS, 453, 3043
Reprint (link to ADS)
Acknowledgment:
Graytrix software heavily uses HEALPix subroutines, TH would like to thank
HEALPix team for making the HEALPix software publicly available.
Graytrix software uses some CALCLENS' functions (transformed to Fortran).
TH would like to thank Matthew R. Becker for making the source codes of
CALCLENS publicly available.
Contact:
Takashi Hamana
Latest update: 2017/5/19
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