We present 36 spectroscopically confirmed intrinsically UV-faint Lyman-alpha emitting galaxies ( LAEs ) from follow-up observations with Keck/DEIMOS of high-redshift candidates behind 10 galaxy cluster lenses .
High-redshift candidates were selected to be between 5 \lesssim z \lesssim 7 from a variety of photometric data using HST and Spitzer imaging surveys .
We used photometric redshift information derived from accompanying photometric data to perform an integrated photometric redshift probability , or , P ( z ) cut > 1 \% between 5 < z < 7 in order to construct a sample of 198 high-redshift objects , 136 primary targets and 62 secondaries ( serendipitous objects ) .
Our high-redshift sample spans intrinsic UV luminosities from a few L ^ { * } down to 0.001 L ^ { * } .
We identified 19 high-confidence detections of Ly \alpha in our final sample and an additional 17 likely detections .
Five of these detections have been previously reported spectroscopically .
We find overall the emission lines to be redward skewed .
We divided our sample into a lower-redshift ( z \sim 5.5 ) and higher-redshift ( z \sim 6.5 ) sample and ran Monte Carlo trials , incorporating the strength of the Ly \alpha emission , the photometric redshift of the non-detections , and different treatments of multiple images .
Considering only objects where Ly \alpha could be detected at EW ( Ly \alpha ) > 25Å at 3 \sigma at the fiducial depth of our survey , and considering only those galaxies with EW ( Ly \alpha ) > 25Å as true LAEs , and finally , considering only objects with m _ { AB } < 26.8 , we found the LAE fraction to be flat , or modestly increase from 0.26 \pm 0.04 to 0.30 \pm 0.04 over the same redshift interval .
These values relative to those at lower-redshift samples are consistent with the rising LAE fraction with redshift out to z \sim 6 found in the literature , but at z \sim 6.5 there is some tension between our results and results from surveys at intrinsically brighter luminosities .
From our analyses we conclude intrinsically fainter galaxies have Ly \alpha emission , and there is a steep drop in the LAE fraction from our high-redshift sample at z \sim 6.5 and from similar galaxies at z \sim 7.5 .
This likely indicates we are witnessing the tail end of the epoch of reionization , as such a drop is not expected due to changes of intrinsic galaxy properties between these redshifts .