Type-I X-ray bursts reveal a fast co-evolving behavior of the corona in an X-ray binary

TL;DR

This paper reports the discovery of a rapid, co-evolving corona in an X-ray binary, observed through type-I X-ray bursts, providing new insights into the corona's formation and dissipation timescales.

Contribution

It presents the first evidence of a corona's quick disappearance and formation in an XRB, constrained by the timing of type-I bursts.

Findings

Corona co-evolves with type-I bursts in less than a second

Rapid corona formation and dissipation observed during X-ray bursts

Findings constrain accretion models in X-ray binaries

Abstract

The coronae in X-ray binaries (XRBs) still remain poorly understood, although they have been believed for a long time to play a key role in modeling the characteristic outbursts of XRBs. Type-I X-ray bursts, the thermonuclear flashes happening on the surface of a neutron star (NS), can be used as a probe to the innermost region of a NS XRB, where the corona is believed to be located very close to the NS. We report the discovery of a tiny life cycle of the corona that is promptly co-evolved with the type-I bursts superimposed on the outburst of the NS XRB IGR J17473$-$2721. This finding may serve as the first evidence of directly seeing the rapid disappearance and formation of a corona in an XRB with a cooling/heating timescale of less than a second, which can strongly constrain the accretion models in XRBs at work.