Following our previous spectroscopic observations of z > 7 galaxies with Gemini/GNIRS and VLT/XSHOOTER , which targeted a total of 8 objects , we present here our results from a deeper and larger VLT/FORS2 spectroscopic sample of Wide Field Camera 3 selected z > 7 candidate galaxies .
With our FORS2 setup we cover the 737-1070nm wavelength range , enabling a search for Lyman- \alpha in the redshift range spanning 5.06 - 7.80 .
We target 22 z -band dropouts and find no evidence of Lyman- \alpha emission , with the exception of a tentative detection ( < 5 \sigma , which is our adopted criterion for a secure detection ) for one object .
The upper limits on Lyman- \alpha flux and the broad-band magnitudes are used to constrain the rest-frame Equivalent Widths for this line emission .
We analyse our FORS2 observations in combination with our previous GNIRS and XSHOOTER observations , and suggest that a simple model where the fraction of high rest-frame Equivalent Width emitters follows the trend seen at z = 3 - 6.5 is inconsistent with our non-detections at z \sim 7.8 at the 96 % confidence level .
This may indicate that a significant neutral HI fraction in the intergalactic medium suppresses Lyman- \alpha , with an estimated neutral fraction \chi _ { HI } \sim 0.5 , in agreement with other estimates .