THE RADIO COSMIC WEB
 

Where is the warm-hot intergalatic medium? Can we observe it at radio wavelenghts? Can we use it to study the magnetisation history of the Universe?
We recently produced very big cosmological MHD simulations to study the evolution of magnetic fields in large-scale structures and quantify the observable signal from the shocked cosmic web in synchrotron.
The sky models generated in this project can be used to test which strategies are best to lead to a detection of the radio cosmic web, with existing (e.g. JVLA, LOFAR, MWA) or incoming radio telescopes (most noticeably the SKA).
All simulations have been produced on Piz-Daint at CSCS
in 2014, using the ENZO code.
Our data are share using the EUDAT service.
Maps & models
 
MODELS:
  • MHD=magnetic field from the MHD simulation, starting from a cosmological B0=1e-10G at z=30.
  • HA=the magnetic field from the MHD run is renormalized to be 1% of the gas energy of cells, whenever n>2n_critical
  • LA=as in HA, but only for n>50n_critical ("low-amplification"model)
  • HSA=as in HA + CR-driven amplification for strong shocks.
Numbering convention for the frames of the fits file:
0=no reacceleration, HA model; 1=HA and shock injection+re-acceleration; 2=LA and shock injection+re-acceleration; 3=HSA and shock injection+re-acceleration; 4=input simulated HD, shock injection and re-acceleration
More details on the models are given HERE.
 
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Here below it is possible to download our fits files containing the sky models generated with our MHD runs. They are meant to represent large areas of the sky and can be used for testing of survey strategies with radio telescopes. Each set of sky models contains the predicted radio emission for different magnetic field models (see right), at the reference frequency of 110 Mhz.
A set of simple IDL routines to read and transform the emission in any given frequency is also given on the right of each panel.
 
STRUCTURE OF FITS FILES
For each .fits file we have the same structure:
fields 0-4 -> projected radio emission in log10[Jy/arcsec^2].
ields 5-9 -> emission-weighted radio spectral index, alfa (where I(freq) \propto freq^(-alfa). (0->5, 1->6 etc).

 
High-resolution, small volume
 
Details:
Box size= 50 Mpc (comoving)
resolution=20.8 kpc (comoving)
2400^3 cells
 
 
RESOURCES FOR ANALYSIS:
 
Here is a sample IDL code to read in the data and compute the emission in a different frequency
 
z=0 fits
z=0.5 fits
IDL CODE
z=1.0 fits
z=2.0 fits
Low-resolution, large volume
 
Details:
Box size= 200 Mpc (comoving)
resolution=166 kpc (comoving)
1200^3 cells
 
 
RESOURCES FOR ANALYSIS:
 
Here is a sample IDL code to read in the data and compute the emission in a different frequency
 
z=0 fits
IDL CODE
z=0.5 fits
z=1.0 fits
Redshift cones
 
Details:
Box size= 100 Mpc (comoving)
This is the result of the stacking of several simuated boxes  to simulate a long radio lightcone.
Each fits contains the increasing contribution from more volume along the line of sight (up to z=0.5).
More details about the procedure for this here.
 
 
RESOURCES FOR ANALYSIS:
 
Here is a sample IDL code to read in the data and compute the emission in a different frequency
 
IDL CODE
COMPLETE RADIO DATASET
X-ray emission
Location of clusters
Maps with cluster removed
1-Dimensional Beams
Here we store 1D beams of cell values for the products of interesting MHD simulations, which are useful to study
Faraday Rotations and Axionlike Particle (ALPs) oscillations.
 
Each dataset is formatted and contains the following comoving quantities (the units are written within the files).
redshift, gas density,DM density, temperature,Bx,By,Bz,Btot
The x-component is the one along the line of sight. 

From z=0 to z=2, high resolution, cosmological seeding

  • 10 random line of sights obtained combining 106 replicae of a simulated 50Mpc comoving volume and different redshifts, with fixed comoving resolution of 20.8kpc.
  • The simulation is non-radiative, and the magnetic fields have been evolved starting from a primordial seed field of 10^-10 G (comoving) from z=30.
  • Cosm. parameters: h=0.702, OmegaM=0.272, OmegaL=0.728, Omega_baryon=0.0455 sigma8=0.8
(single datasets via Eudat)
(all data zipped)

From z=0 to z=2, lower resolution, cosmological vs astrophysical seeding

  • 10 random line of sights obtained combining 27 replicae of a simulated 200Mpc comoving volume and different redshifts, with fixed comoving rsolution of 166.6kpc.
Here we compare 2 resimulations of the same volume:
  •  the "cR" run has radiative cooling and the magnetic fields  have been evolved starting from a primordial seed field of 10^-11 G (comoving) from z=30;
  •  the "cqhR" also has thermal/magnetic feedback by active galactic nuclei, and hence at the highest density peak in the volume the temperaure and magnetic fields are higher than in the previous run.
  • Cosm. parameters: h=0.678, OmegaM=0.308, OmegaL=0.692, Omega_baryon= 0.0478, sigma8=0.815
(single datasets via Eudat)
(all data zipped)

From z=0 to z=1, cosmological seeding, 2400CHRONOS++ largest run. 

  • 100 random line of sights extracted from a 2003 Mpc3 (comoving) volume simulated with 24003 cells and DM particles (for a comoving resolution of 83.3kpc/cell). 
  • Each line of sight is a tabulated list of values written in a formatted way: redshift, electrons density [g/cm^3], DM density [g/cm^3],T[K],Bx[G],By[G],Bz[G],Btot[G]. All fields are in comoving units. The x-component of magnetic fiels is the one that runs along the line of sight. 
  • The simulation is non-radiative. The magnetic field is initialised at z=50 to B0=1e-9G (comoving), uniformly in all directions. 
  • Cosm. parameters: h=0.678, OmegaM=0.308, OmegaL=0.692, Omega_baryon= 0.0478, sigma8=0.815
(all data zipped via Eudat)