Luminosity distance and anisotropic sky-sampling at low redshift: a numerical relativity study

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• Hayley Macpherson (DAMTP)
• Friday 28 May 2021, 13:00-14:00
• Zoom.

If you have a question about this talk, please contact Justin Ripley.

Most cosmological data analysis today relies on the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, providing the basis of the current standard cosmological model. Within this framework, interesting tensions between our increasingly precise data and theoretical predictions are coming to light. It is therefore timely to explore the potential for cosmological analysis outside of the exact FLRW cosmological framework. I will discuss our recent work using Heinesen’s new luminosity-distance series expansion in redshift, which contains no assumptions on the form of the metric tensor or field equations. This framework will allow for a full model-independent analysis of near-future low-redshift cosmological surveys. I will present our calculations of the anisotropy in the effective observational ‘Hubble’, ‘deceleration’, ‘curvature’ and ‘jerk’ parameters in cosmological simulations using numerical relativity. We find the dependence on observer position— `cosmic variance’— of the Hubble parameter is consistent with previous studies. However, on top of this, typical observers in our simulations measure maximal anisotropic sky-variance of 7% and 550% in the Hubble and deceleration parameters, respectively. Our results suggest the inclusion of low-redshift anisotropy in cosmological analysis could be important for drawing correct conclusions about global properties of our Universe.

This talk is part of the DAMTP Friday GR Seminar series.

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