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SUMMARY:Luminosity distance and anisotropic sky-sampling at low redshift: 
 a numerical relativity study - Hayley Macpherson (DAMTP)
DTSTART:20210528T120000Z
DTEND:20210528T130000Z
UID:TALK158776@talks.cam.ac.uk
CONTACT:Justin Ripley
DESCRIPTION:Most cosmological data analysis today relies on the Friedmann-
 Lemaitre-Robertson-Walker (FLRW) metric\, providing the basis of the curre
 nt standard cosmological model. Within this framework\, interesting tensio
 ns between our increasingly precise data and theoretical predictions are c
 oming to light. It is therefore timely to explore the potential for cosmol
 ogical analysis outside of the exact FLRW cosmological framework. I will d
 iscuss our recent work using Heinesen's new luminosity-distance series exp
 ansion in redshift\, which contains no assumptions on the form of the metr
 ic tensor or field equations. This framework will allow for a full model-i
 ndependent analysis of near-future low-redshift cosmological surveys. I wi
 ll present our calculations of the anisotropy in the effective observation
 al 'Hubble'\, 'deceleration'\, 'curvature' and 'jerk' parameters in cosmol
 ogical simulations using numerical relativity. We find the dependence on o
 bserver position --- `cosmic variance' --- of the Hubble parameter is cons
 istent 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 su
 ggest the inclusion of low-redshift anisotropy in cosmological analysis co
 uld be important for drawing correct conclusions about global properties o
 f our Universe.
LOCATION:Zoom
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