  GRS 1915+105 is a transient black hole X-ray binary consistently emitting
10-100% of the Eddington luminosity in the X-ray band during the last three
decades until mid-2018 when the source luminosity suddenly decreased by an
order of magnitude. This phase was followed by a change to a state with even
lower average X-ray fluxes never seen before during the outburst but presenting
renewed flaring activity at different wavelengths. Nevertheless, the mean
fluxes were still in decline. GRS 1915+105 has the longest orbital period known
among low-mass X-ray binaries, the largest accretion disk size, and therefore
the largest mass supply for accretion. The high inclination of the disk allows
the study of geometrical effects of the accretion flow such as changes in the
height-to-radius ratio or the effect of accretion disk winds on the intrinsic
emission that are expected during the outburst decay. In addition, the
transient jet is expected to change to a compact, self-absorbed, steady jet. We
conducted two full polarization Atacama Large Millimeter Array observations to
study the jet properties during the outburst decay by analyzing the spectral,
polarization, and intra-epoch variability for both observation epochs. In
addition, we analyzed nearly daily Neutron Star Interior Composition Explorer
pointing observations consisting of modeling X-ray power spectral densities,
spectral energy distributions, and lightcurves with a physically motivated
model to follow the changing accretion disk properties throughout the outburst
decay and relating them to the jet emission. We show that the X-ray and mm
spectral, timing, and polarization properties are consistent with those of a
typical decaying X-ray binary outburst and that GRS 1915+105 has descended into
the low-luminosity hard X-ray state.
