As my Ph. D. thesis, I have studied particle acceleration environment of supernova remnants (SNRs) through X-rays and gamma-rays. Maximum energies of accelerated particles and their dependence on environments were of particular interest. Investigating each SNR is not enough to study the evolution of the maximum energies. Thus I have used almost all the available objects. I had to quantify the uncertainties of their age estimates, because the ages of SNRs have long been unreliable for most cases, without truly quantitative uncertainties.
As a result, I found that the maximum attainable energies of SNRs on average can reach PeV if the maximum is achieved at ages smaller than ~10 yr. On the other hand, a large variety of the maximum energies at the same ages (1-2 dex) was suggested. This will be natural given the environmental parameter dependence of the maximum energies predicted in theoretical works.
I believe that this work provides the first results to quantify the contribution of SNRs to the non-thermal evolution of out Galaxy. Although my results are not yet crucial without remarkably tight constraints on the acceleration physics due to limited statistics, this approach will work greatly with future observations with, e.g., Cherenkov Telescope Array.