Lyα emitting galaxies can be used to study cosmological reionization, because a neutral intergalactic medium (IGM) scatters Lyα photons into diffuse halos whose surface brightness falls below typical survey detection limits. Here, we present the Lyα emitting galaxy LAE J095950.99+021219.1, identified at redshift z = 6.944 in the COSMOS field using narrowband imaging and follow-up spectroscopy with the IMACS instrument on the Magellan I Baade telescope. With a single object spectroscopically confirmed so far, our survey remains consistent with a wide range of IGM neutral fraction at z 7, but further observations are planned and will help clarify the situation. Meantime, the object we present here is only the third Lyα-selected galaxy to be spectroscopically confirmed at z ≳ 7, and is 2-3 times fainter than the previously confirmed z 7 Lyα galaxies.
- dark ages, reionization, first stars
- galaxies: high-redshift
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science