Abstract
The background photon temperature is one of the fundamental cosmological parameters, and it is often set equal to the precise measurement of the comic microwave background (CMB) temperature by the COBE Far Infrared Absolute Spectrometer (FIRAS). However, even in future CMB experiments, will remain unknown due to the unknown monopole contribution at our position to the observed (angle-averaged) temperature . Using the Fisher formalism, we find that the standard analysis with underestimates the error bars on cosmological parameters by of the present errors, and the best-fit parameters obtained in the analysis are biased by of their standard deviation. These systematic errors are negligible for the Planck data analysis, providing a justification to the standard practice. However, with , these systematic errors will always be present and irreducible, and future cosmological surveys might misinterpret the measurements.
- Received 24 May 2019
- Revised 31 July 2019
DOI:https://doi.org/10.1103/PhysRevD.100.063510
© 2019 American Physical Society