Lyman Alpha Galaxies in the Epoch of Reionization (LAGER): Spectroscopic
  Confirmation of Two Redshift ~ 7.0 Galaxies
  We spectroscopically confirmed two narrow-band selected redshift 7.0
Ly$\alpha$ galaxies and studied their restframe UV spectra. The Ly$\alpha$ and
other UV nebular lines are very useful to confirm the galactic redshifts and
diagnose the different mechanisms driving the ionizing emission. We observed
two narrowband-selected $z$=7.0 Ly$\alpha$ candidates in the LAGER Chandra Deep
Field South (CDFS) field with IMACS at Magellan telescope and confirmed they
are Ly$\alpha$ emitters at $z$=6.924 and 6.931. In one galaxy, we also obtained
deep NIR spectroscopy, which yields non-detections of the high-ionization UV
nebular lines. We measured upper-limits of the ratios of
CIV$\lambda$1548/Ly$\alpha$, HeII$\lambda$1640/Ly$\alpha$,
OIII]$\lambda$1660/Ly$\alpha$, and CIII]$\lambda$1909/Ly$\alpha$ from the NIR
spectra. These upper-limits imply that the ionizing emission in this galaxy is
dominated by normal star formation instead of AGN.
