Oscillating wind accretion due to X-ray inhibition of line-driven mechanism.

This article investigates how X-ray ionization from a compact object in high-mass X-ray binaries (HMXBs) affects the line-driven acceleration of stellar winds from a massive donor star, influencing the mass accretion process. Using a simplified ballistic model that treats stellar wind matter as point particles accelerated by a pseudo-CAK (Castor–Abbott–Klein) potential, the study demonstrates that X-ray irradiation can inhibit wind acceleration, causing spontaneous oscillations in the mass accretion rate and resulting in quasiperiodic X-ray flares. The model shows distinct behaviors for black hole and neutron star accretors, with stronger ionization effects and flare activity in black hole systems due to higher X-ray luminosities. While the toy model neglects hydrodynamic effects and X-ray absorption, it suggests that feedback between X-ray ionization and wind acceleration may underlie observed variability in wind-fed HMXBs and supergiant fast X-ray transients (SFXTs).