Flip-flop QPO changes during state transitions: a case study of GX339-4 and theoretical discussion

D. J. K. Buisson, G. Marcel, V. López-Barquero +3

We analyse the 2021 outburst from the black hole X-ray binary GX339-4 observed by NICER around the hard to soft transition, when the system exhibits flip-flops between two distinct…