Analyzing the Large-Scale Bulk Flow using CosmicFlows4: Increasing Tension with the Standard Cosmological Model

Understand

We present an estimate of the bulk flow in a volume of radii $150-200h^{-1}$Mpc using the minimum variance (MV) method with data from the CosmicFlows-4 (CF4) catalog.

• The addition of new data in the CF4 has resulted in an increase in the estimate of the bulk flow in a sphere of radius $150h^{-1}$Mpc relative to the CosmicFlows-3 (CF3).
• This bulk flow has less than a $0.03\%$ chance of occurring in the Standard Cosmological Model ($\Lambda$CDM) with cosmic microwave background derived parameters.
• Given that the CF4 is deeper than the CF3, we were able to use the CF4 to accurately estimate the bulk flow on scales of $200h^{-1}$Mpc (equivalent to 266 Mpc for Hubble constant $H_o=75$ km/s/Mpc) for the first time.