The Quasar SDSS J1536+0441: An Unusual Double-Peaked Emitter
  The quasar SDSS J153636.22+044127.0, exhibiting peculiar broad emission-line
profiles with multiple components, was proposed as a candidate sub-parsec
binary supermassive black hole system. More recently, imaging revealed two
spatially distinct sources, leading some to suggest the system to be a quasar
pair separated by ~5 kpc. We present Palomar and Keck optical spectra of this
system from which we identify a third velocity component to the emission lines.
We argue that the system is more likely an unusual member of the class of
active galactic nuclei (AGNs) known as "double-peaked emitters" than a
sub-parsec black hole binary or quasar pair. We find no significant velocity
evolution of the two main peaks over the course of 0.95 yr, with a 3-sigma
upper limit on any secular change of 70 km/s/yr. We also find that the three
velocity components of the emission lines are spatially coincident to within
0.015" along the slit, apparently ruling out the double-quasar hypothesis.
