We present the spectral and timing analysis of X-ray observations performed on the Galactic black hole transient GRS 1716–249 during the 2016-2017 outburst .
The source was almost continuously observed with the Neil Gehrels Swift Observatory from December 2016 until October 2017 .
The X-ray hardness ratio and timing evolution indicate that the source approached the soft state three times during the outburst , even though it never reached the canonical soft spectral state .
Thus , GRS 1716–249 increases the number of black hole transients showing outbursts with ‘ ‘ failed '' state transition .
During the softening events , XRT and BAT broadband spectral modeling , performed with thermal Comptonization plus a multicolor disc black-body , showed a photon index ( \Gamma < 2 ) and an inner disc temperature ( kT _ { in } = 0.2-0.5 keV ) characteristic of the hard intermediate state .
This is in agreement with the root mean square amplitude of the flux variability ( rms > 10 \% ) .
We find that , coherently with a scenario in which the disc moves closer to the compact object , the accretion disc inner radius decreases with the increase of the inner disc temperature , until a certain point when the temperature starts to increase at constant radius .
This , in addition with the spectral analysis results , suggests that either the accretion disc reached the innermost stable circular orbit during the hard intermediate state or the hot accretion flow might re-condensate in an inner mini-disc .
We report on the radio observations performed during the outburst finding that GRS 1716–249 is located on the radio-quiet ‘ ‘ outlier '' branch of the radio/X-ray luminosity plane .