A Black Hole Nova Obscured by an Inner Disk Torus
  Stellar-mass black holes (BHs) are mostly found in X-ray transients, a
subclass of X-ray binaries that exhibit violent outbursts. None of the 50
Galactic BHs known show eclipses, which is surprising for a random distribution
of inclinations. Swift J1357.2-0933 is a very faint X-ray transient detected in
2011. On the basis of spectroscopic evidence, we show that it contains a BH in
a 2.8 h orbital period. Further, high-time resolution optical light curves
display profound dips without X-ray counterparts. The observed properties are
best explained by the presence of an obscuring toroidal structure moving
outwards in the inner disk seen at very high inclination. This observational
feature should play a key role in models of inner accretion flows and jet
collimation mechanisms in stellar-mass BHs.
