‘tidal UDGs’, a population of galaxies transformed into UDGs as a result of tidal stripping, begin to dominate the population, as UDGs that fell into the cluster as UDGs are now destroyed. Finally, it should also be noted that the highly disturbed nature of the Frontier Fields clusters renders the choice of cluster centre rather uncertain.

The abundance of ultra-diffuse galaxies
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![ Abundance of UDGs as a function of halo mass for the 6 FF clusters examined in this work, as well as other systems from the literature (see text for details). The solid line is the best fit power law to the abundances in the FFs as well as the binned groups from [@vdb2017] and the clusters from [@vdb2016]. \[fig:abundance\] ](figure7.pdf){width="50.00000%"}

An estimate for the total number of UDGs in each cluster is made by integrating the corrected surface number density profile out to $R_{200}$. These total abundances are listed in the last column of Table \[tab:clusters\] and range from ${\sim}200$ in MACS 0416 to ${\sim}1400$ in Abell 2744 and Abell S1063. Note that for Abell 2744, Abell S1063 and Abell 370, where we have to extrapolate out to $R_{200}$, we assume the surface density observed in the 