SDSS-IV MaNGA: The Spectroscopic Discovery of Strongly Lensed Galaxies
  We present a catalogue of 38 spectroscopically detected strong galaxy-galaxy
gravitational lens candidates identified in the Sloan Digital Sky Survey IV
(SDSS-IV). We were able to simulate narrow-band images for 8 of them
demonstrating evidence of multiple images. Two of our systems are compound lens
candidates, each with 2 background source-planes. One of these compound systems
shows clear lensing features in the narrow-band image. Our sample is based on
2812 galaxies observed by the Mapping Nearby Galaxies at APO (MaNGA) integral
field unit (IFU). This Spectroscopic Identification of Lensing Objects (SILO)
survey extends the methodology of the Sloan Lens ACS Survey (SLACS) and BOSS
Emission-Line Survey (BELLS) to lower redshift and multiple IFU spectra. We
searched ~ 1.5 million spectra, of which 3065 contained multiple high
signal-to-noise background emission-lines or a resolved [OII] doublet, that are
included in this catalogue. Upon manual inspection, we discovered regions with
multiple spectra containing background emission-lines at the same redshift,
providing evidence of a common source-plane geometry which was not possible in
previous SLACS and BELLS discovery programs. We estimate more than half of our
candidates have an Einstein radius > 1.7", which is significantly greater than
seen in SLACS and BELLS. These larger Einstein radii produce more extended
images of the background galaxy increasing the probability that a background
emission-line will enter one of the IFU spectroscopic fibres, making detection
more likely.
