Bulk flow in the combined 2MTF and 6dFGSv surveys

Understand

We create a combined sample of 10,904 late and early-type galaxies from the 2MTF and 6dFGSv surveys in order to accurately measure bulk flow in the local Universe.

• Galaxies and groups of galaxies common between the two surveys are used to verify that the difference in zero-points is $<0.02$ dex.
• We introduce a maximum likelihood estimator ($\eta$MLE) for bulk flow measurements which allows for more accurate measurement in the presence non-Gaussian measurement errors.
• To calibrate out residual biases due to the subtle interaction of selection effects, Malmquist bias and anisotropic sky distribution, the estimator is tested on mock catalogues generated from 16 independent large-scale GiggleZ and SURFS simulations.