On the nature of the soft gamma-ray emission in the hard state of the black hole transient GRS 1716-249

Understand

The black hole transient GRS 1716-249 was monitored from the radio to the gamma-ray band during its 2016-2017 outburst.

• This paper focuses on the Spectral Energy Distribution (SED) obtained in 2017 February-March, when GRS 1716-249 was in a bright hard spectral state.
• The soft gamma-ray data collected with the INTEGRAL/SPI telescope show the presence of a spectral component which is in excess of the thermal Comptonisation emission.
• This component is usually interpreted as inverse Compton emission from a tiny fraction of non-thermal electrons in the X-ray corona.