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GRS 1915$+$105 is a stellar-mass black hole that is well known for exhibitingat least 12 distinct classes of X-ray variability and correlatedmulti-wavelength behavior. Despite such extraordinary variability, GRS1915$+$105 remained one of the brightest sources in the X-ray sky. However, inearly 2019, the source became much fainter, apparently entering a new accretionstate. Here, we report the results of an extensive, year-long monitoringcampaign of GRS 1915$+$105 with the Neil Gehrels Swift Observatory. During thisinterval, the flux of GRS 1915$+$105 gradually diminished; the observed countrate eventually dropped by two orders of magnitude. Simple but robust spectralfits to these monitoring observations show that this new state results from thecombination of a dramatic and persistent increase in internal obscuration, anda reduced mass accretion rate. The internal obscuration is the dominant effect,with a median value of $N_{H} = 7\times 10^{23}~{\rm cm}^{-2}$. In a number ofobservations, the source appears to be Compton-thick. We suggest that thisstate should be identified as the "obscured state," and discuss theimplications of this new (or rarely observed) accretion mode for black holesacross the mass scale.

The Novel Obscured State of Stellar-mass Black Hole GRS 1915+105