Christian Fidler

Contact details

Current position: Post-doctoral researcher at Aachen University (Germany)

I am interested in the dynamics of the Universe, both at early times related to the CMB and at late times for the large scale structure.

I am involved in the development of the non-linear Boltzmann code SONG. This code simulates the early Universe at unrivalled precision including all standard model species.
Currently it is used to compute:
  • B mode polarisation of the CMB induced from non-linear dynamics after inflation
  • Non-Guassianity in the temperature and polarisation of the CMB from non-linear dynamics
  • Spectral Distortions in the CMB from reionisation
Working on this project I have gained valuable experience in numerical simulations and programming. I also have a good understanding of numerical mathematics and have designed several new methods fit for the computations performed by SONG.
Theoretical Cosmology
I am working on the theoretical framework related to non-linear simulations.
My work contributes to developing the framework of second-order cosmological perturbation theory. I have derived the polarised non-linear Boltzmann equations.
I am working on a new formalism for non-linear propagation of photons in curved spaces.

Publications @ Inspire @ ADS @ arXiv

Publications @ CURL


  • [1] Fidler C and Pitrou C 2017 Kinetic theory of fermions in curved spacetime JCAP 1706 013
    Abstract: arXiv:1701.08844
    Journal: 10.1088/1475-7516/2017/06/013

  • [2] Fidler C, Tram T, Rampf C, Crittenden R, Koyama K and Wands D 2017 Relativistic initial conditions for N-body simulations JCAP 1706 043
    Abstract: arXiv:1702.03221
    Journal: 10.1088/1475-7516/2017/06/043

  • [3] Adamek J, Brandbyge J, Fidler C, Hannestad S, Rampf C and Tram T 2017 The effect of early radiation in N-body simulations of cosmic structure formation Mon. Not. Roy. Astron. Soc. 470 303–13
    Abstract: arXiv:1703.08585
    Journal: 10.1093/mnras/stx1157

  • [4] Fidler C, Tram T, Rampf C, Crittenden R, Koyama K and Wands D 2017 General relativistic weak-field limit and Newtonian N-body simulations JCAP 1712 022
    Abstract: arXiv:1708.07769
    Journal: 10.1088/1475-7516/2017/12/022

  • [5] Fidler C and Ringeval C 2017 CMB anisotropies from patchy reionisation and diffuse Sunyaev-Zel’dovich effects JCAP 1710 026
    Abstract: arXiv:1709.01395
    Journal: 10.1088/1475-7516/2017/10/026

  • 2016

  • [1] Fidler C, Pettinari G and Pitrou C 2016 Precise numerical estimation of the magnetic field generated around recombination Phys. Rev. D93 103536
    Abstract: arXiv:1511.07801
    Journal: 10.1103/PhysRevD.93.103536

  • [2] Tram T, Fidler C, Crittenden R, Koyama K, Pettinari G W and Wands D 2016 The Intrinsic Matter Bispectrum in \LambdaCDM JCAP 1605 058
    Abstract: arXiv:1602.05933
    Journal: 10.1088/1475-7516/2016/05/058

  • [3] Fidler C, Tram T, Rampf C, Crittenden R, Koyama K and Wands D 2016 Relativistic Interpretation of Newtonian Simulations for Cosmic Structure Formation JCAP 1609 031
    Abstract: arXiv:1606.05588
    Journal: 10.1088/1475-7516/2016/09/031

  • [4] Brandbyge J, Rampf C, Tram T, Leclercq F, Fidler C and Hannestad S 2016 Cosmological N-body simulations including radiation perturbations
    Abstract: arXiv:1610.04236
    Journal: 10.1093/mnrasl/slw235

  • 2015

  • [1] Fidler C, Rampf C, Tram T, Crittenden R, Koyama K and Wands D 2015 General relativistic corrections to N-body simulations and the Zel’dovich approximation Phys. Rev. D92 123517
    Abstract: arXiv:1505.04756
    Journal: 10.1103/PhysRevD.92.123517