# Lyman Alpha Galaxies in the Epoch of Reionization (LAGER): Spectroscopic Confirmation of Two Redshift ~ 7.0 Galaxies

## TL;DR

This study spectroscopically confirmed two galaxies at redshift around 7, demonstrating the effectiveness of Ly$ extalpha$ lines in identifying early universe galaxies and analyzing their ionizing sources.

## Contribution

First spectroscopic confirmation of two z~7 Ly$ extalpha$ galaxies using narrowband selection and UV spectral analysis, providing insights into their ionizing mechanisms.

## Key findings

- Confirmed two Ly$ extalpha$ emitters at z=6.924 and 6.931.
- Non-detections of high-ionization UV lines suggest star formation dominates ionizing emission.
- Upper limits on UV line ratios indicate no strong AGN activity.

## Abstract

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.