Power spectrum emulator

Code description

Emu CMB is a fast emulator the CMB temperature power spectrum based on CAMB (Jan 2010 version).

  • Inputs for 6 parameter cosmological model:
    • ns
    • ln(1010 As)
    • 100 &theta*
    • &Omegac h2
    • &Omegab h2
    • &tau
  • Maximum multipole l = 5238
  • Lensing included
  • Matches CAMB output to 0.6% over WMAP5 prior parameter range
  • Python and IDL versions
Emu CMB is based on a "space-filling" Orthogonal Array Latin Hypercube design in a de-correlated parameter space obtained by using a fiducial WMAP5 CMB Fisher matrix as a rotation matrix.  This design strategy allows for accurate interpolation with small numbers of simulation design points.  The emulator presented here is calibrated with 100 CAMB runs that are interpolated over the design space using a global quadratic polynomial fit.

The construction and performance of the code are described in detail in Schneider, Holm & Knox (2010) (arXiv:1002:1752).

CAMB parameter file used to generate one of the design runs.


Download version 1.0.1 of Emu CMB here.

Please cite Schneider, Holm & Knox (2010) in any publications making use of Emu CMB.

Emulator Accuracy

We have tested the interpolation accuracy by interpolating to 100 new locations within a 4-sigma hypersphere in our fiducial WMAP5 prior distribution in the 6-parameter design space.
Here are the fractional interpolation errors in the power spectra:


Emu CMB is written by Michael Schneider and Lloyd Knox.

Please use the forum at CosmoCoffee to discuss usage of the code.