%0 Generic %1 mcgreer2014modelindependent %A McGreer, Ian %A Mesinger, Andrei %A D'Odorico, Valentina %D 2014 %K HI end fraction igm neutral reionization %T Model-independent evidence in favor of an end to reionization by z~6 %U http://arxiv.org/abs/1411.5375 %X We present new upper limits on the volume-weighted neutral hydrogen fraction, <xHI>, at z~5-6 derived from spectroscopy of bright quasars. The fraction of the Lyman-alpha and Lyman-beta forests that is "dark" (with zero flux) provides the only model-independent upper limit on <xHI>, requiring no assumptions about the physical conditions in the intergalactic medium or the quasar's unabsorbed UV continuum. In this work we update our previous results using a larger sample (22 objects) of medium-depth (~ few hours) spectra of high-redshift quasars obtained with the Magellan, MMT, and VLT. This significantly improves the upper bound on <xHI> derived from dark pixel analysis to <xHI> <= 0.06 + 0.05 (1\sigma) at z=5.9, and <xHI> <= 0.04 + 0.05 (1\sigma) at z=5.6. These results provide robust constraints for theoretical models of reionization, and provide the strongest available evidence that reionization has completed (or is very nearly complete) by z~6.

@misc{mcgreer2014modelindependent, abstract = {We present new upper limits on the volume-weighted neutral hydrogen fraction, <xHI>, at z~5-6 derived from spectroscopy of bright quasars. The fraction of the Lyman-alpha and Lyman-beta forests that is "dark" (with zero flux) provides the only model-independent upper limit on <xHI>, requiring no assumptions about the physical conditions in the intergalactic medium or the quasar's unabsorbed UV continuum. In this work we update our previous results using a larger sample (22 objects) of medium-depth (~ few hours) spectra of high-redshift quasars obtained with the Magellan, MMT, and VLT. This significantly improves the upper bound on <xHI> derived from dark pixel analysis to <xHI> <= 0.06 + 0.05 (1{\sigma}) at z=5.9, and <xHI> <= 0.04 + 0.05 (1{\sigma}) at z=5.6. These results provide robust constraints for theoretical models of reionization, and provide the strongest available evidence that reionization has completed (or is very nearly complete) by z~6.}, added-at = {2014-11-21T09:56:48.000+0100}, author = {McGreer, Ian and Mesinger, Andrei and D'Odorico, Valentina}, biburl = {https://www.bibsonomy.org/bibtex/2de39608ac7d2d43914c54430d362d84a/miki}, description = {[1411.5375] Model-independent evidence in favor of an end to reionization by z~6}, interhash = {696c757677fa2c57838042e8623a89b1}, intrahash = {de39608ac7d2d43914c54430d362d84a}, keywords = {HI end fraction igm neutral reionization}, note = {cite arxiv:1411.5375Comment: 8 pages, 4 figures, accepted for publication by MNRAS}, timestamp = {2014-11-21T09:56:48.000+0100}, title = {Model-independent evidence in favor of an end to reionization by z~6}, url = {http://arxiv.org/abs/1411.5375}, year = 2014 }