Cosmological perturbations of unimodular gravity and general relativity are identical

  title={Cosmological perturbations of unimodular gravity and general relativity are identical},
  author={Abhishek Basak and Oph'elia Fabre and S. Shankaranarayanan},
  journal={General Relativity and Gravitation},
Unimodular gravity (UG) is a restricted version of general relativity (GR) in which the variation of the metric determinant is set to zero and the field equations are given by the trace-free part of the full Einstein equations. The background equations in UG and GR are identical. It was recently claimed that the first order contribution in the temperature fluctuations of the Cosmic Microwave Background (CMB) in UG is different from GR. In this work, we calculate the first order perturbation… 

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