2 axis on a graph

Hi, I would like to have 2 different horizontal axis in my TMultiGraph, one for the energy and the other for the sqrt of the Energy, the former for clarification and the latter as the actual argument for my graph in order to perform some linear fits. Is there a way to achieve this? I already have the graphs fitted, I just need to add a second axis for visual clarification. Thanks,

You need to draw a TGaxis. See example here:

root.cern.ch/root/html/tutorials … pad.C.html
root.cern.ch/root/html/tutorials … xis.C.html