Insight-HXMT high energy X-ray obs. of EXO1846-031

The continuum spectrum is well modeled with an absorbed disk-blackbody plus cutoff power law, in the hard, intermediate, and soft states. In addition, we detect an ~6.6keV Fe emission line in the hard intermediate state.

Throughout the soft intermediate and soft states, the fitted inner disk radius remains almost constant; we suggest that it has settled at the innermost stable circular orbit (ISCO). However, in the hard and hard intermediate states, the apparent inner radius was unphysically small (smaller than the ISCO), even after accounting for the Compton scattering of some of the disk photons by the corona in the fit. We argue that this is the result of a high hardening factor, f_col_~2.0-2.7, in the early phases of the outburst evolution, well above the canonical value of 1.7 suitable for a steady disk.