An observational argument against accretion in magnetars
It turns out that one can easily distinguish accreting and non-accreting neutron stars based on their variability! The paper which we've just published settles a years-long dispute on whether persistent emission of magnetars could actually be powered by accretion, and the answer is "no". This conclusion is based on a simple fact that all accreting objects we know are variable (have noise in their power spectra), and all non-accreting objects (including magnterars) are not as is illustrated in figure below from the paper:
Surprisingly, the short and easy paper caused quite a bit of feedback with me getting messages from Ali Alpar, Sandro Mereghetti, Nikos Kylafis, and others. Some agreeing, and some disagreeing, but all friendly! Thanks for feedback and I really hope our result will be useful.