%0 Generic %1 caruana2013spectroscopy %A Caruana, Joseph %A Bunker, Andrew J. %A Wilkins, Stephen M. %A Stanway, Elizabeth R. %A Lorenzoni, Silvio %A Jarvis, Matt J. %A Elbert, Holly %D 2013 %K igm lya neutral transfer %T Spectroscopy of z ~ 7 candidate galaxies: Using Lyman-alpha to constrain the neutral fraction of hydrogen in the high-redshift universe %U http://arxiv.org/abs/1311.0057 %X 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. 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 $z\sim7.8$ 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 $\chi_HI\sim0.5$, in agreement with other estimates.

@misc{caruana2013spectroscopy, abstract = {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. 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 $z\sim7.8$ 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 $\chi_{HI}\sim0.5$, in agreement with other estimates.}, added-at = {2013-11-05T19:56:25.000+0100}, author = {Caruana, Joseph and Bunker, Andrew J. and Wilkins, Stephen M. and Stanway, Elizabeth R. and Lorenzoni, Silvio and Jarvis, Matt J. and Elbert, Holly}, biburl = {https://www.bibsonomy.org/bibtex/2532d63aeedce701444ab8c063acc41a7/miki}, description = {[1311.0057] Spectroscopy of z ~ 7 candidate galaxies: Using Lyman-alpha to constrain the neutral fraction of hydrogen in the high-redshift universe}, interhash = {67c4b5c5c562ac2933bcd8cd39d31039}, intrahash = {532d63aeedce701444ab8c063acc41a7}, keywords = {igm lya neutral transfer}, note = {cite arxiv:1311.0057Comment: submitted to MNRAS}, timestamp = {2013-11-05T19:56:25.000+0100}, title = {Spectroscopy of z ~ 7 candidate galaxies: Using Lyman-alpha to constrain the neutral fraction of hydrogen in the high-redshift universe}, url = {http://arxiv.org/abs/1311.0057}, year = 2013 }