Editor’s Note: In these last two weeks of 2015, we’ll be looking at a few selections from among the most-downloaded papers published in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.
Lyα Emission from a Luminous z = 8.68 Galaxy: Implications for Galaxies as Tracers of Cosmic Reionization
Published August 2015
Main takeaway:
A team led by Adi Zitrin (Hubble Fellow at California Institute of Technology) detected Lyα emission in the bright galaxy EGSY8p7 using the MOSFIRE spectrograph at Keck Observatory. From this emission line, they calculated that the galaxy has an astonishing redshift of z=8.68.
Why it’s interesting:
This spectroscopic confirmation crowned EGSY8p7 as the record-holder for the farthest-known (and therefore oldest) galaxy. Its redshift shattered the previous record, a galaxy at z=7.73.
Why it’s even more interesting than that:

Spectroscopic detection of emission in EGSY8p7 with MOSFIRE. The black line is the raw data; the red line shows the best-fit model to the data. [Zitrin et al. 2015]
Citation
Adi Zitrin et al 2015 ApJ 810 L12. doi:10.1088/2041-8205/810/1/L12