The black hole transient GRS 1915+105 entered a new phase of activity in
2018, generally characterised by low X-ray and radio fluxes. This phase has
been only interrupted by episodes of strong and variable radio emission, during
which high levels of X-ray absorption local to the source were measured. We
present 18 epochs of near-infrared spectroscopy (2018-2023) obtained with
GTC/EMIR and VLT/X-shooter, spanning both radio-loud and radio-quiet periods.
We demonstrate that radio-loud phases are characterised by strong P-Cygni line
profiles, indicative of accretion disc winds with velocities of up to
∼3000kms−1. This velocity is consistent with those measured
in other black hole transients. It is also comparable to the velocity of the
X-ray winds detected during the peak outburst phases in GRS 1915+105,
reinforcing the idea that massive, multi-phase outflows are characteristic
features of the largest and most powerful black hole accretion discs.
Conversely, the evolution of the Brγ line profile during the radio-quiet
phases follows the expected trend for accretion disc lines in a system that is
gradually decreasing its intrinsic luminosity, exhibiting weaker intensities
and more pronounced double-peaks.Comment: Accepted for publication in A&A Letter