The truncated and evolving inner accretion disc of the black hole GX 339-4

Understand

The nature of accretion onto stellar mass black holes in the low/hard state remains unresolved, with some evidence suggesting that the inner accretion disc is truncated and replaced by a hot flow.

• However, the detection of relativistic broadened Fe emission lines, even at relatively low luminosities, seems to require an accretion disc extending fully to its innermost stable circular orbit.
• Modelling such features is however highly susceptible to degeneracies, which could easily bias any interpretation.
• We present the first systematic study of the Fe line region to track how the inner accretion disc evolves in the low/hard state of the black hole GX 339$-$4.