The emission-absorption anticorrelation of IGR J17091-3624 in its extraordinary 2022 outburst observed by NICER and NuSTAR

IGR J17091-3624 is the only black hole X-ray binaries (BHXB) that exhibits exotic "heartbeat"-like variaility in its X-ray light curve besides GRS 1915+105. It can be seen as a bridge between the most peculiar BHXB GRS 1915+105 and "normal" BHXBs, because it alternates the conventional and exotic behaviour of BHXBs. Recently, IGR J17091-3624 went into outburst for the first time in the NICER/NuSTAR era. These exquisite data allow us to simultaneously track the exotic variability and the corresponding spectral features with unprecedented detail. The observations cover the traditional initial hard state, intermediate state, and an exotic soft state where we see two exotic variability classes and one quiet class with a never-before-seen quasi-periodic oscillation (QPO). The flux-energy spectra show broad iron line emission due to relativistic reflection in the states without exotic variability, and absorption features from highly ionized iron in the states exhibiting exotic variability. These observations present crucial constraints on our understanding of accretion-ejection connection in accreting black holes. We discuss the physical nature of the exotic variability and outflows in light of this new legacy dataset.