%0 Generic %1 bosman2021hydrogen %A Bosman, Sarah E. I. %A Davies, Frederick B. %A Becker, George D. %A Keating, Laura C. %A Davies, Rebecca L. %A Zhu, Yongda %A Eilers, Anna-Christina %A D'Odorico, Valentina %A Bian, Fuyan %A Bischetti, Manuela %A Cristiani, Stefano V. %A Fan, Xiaohui %A Farina, Emanuele P. %A Haehnelt, Martin G. %A Kulkarni, Girish %A Mesinger, Andrei %A Meyer, Romain A. %A Onoue, Masafusa %A Pallottini, Andrea %A Qin, Yuxiang %A Ryan-Weber, Emma %A Schindler, Jan-Torge %A Walter, Fabian %A Wang, Feige %A Yang, Jinyi %D 2021 %K library %T Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample %U http://arxiv.org/abs/2108.03699 %X The presence of excess scatter in the Ly-$\alpha$ forest at $z5.5$, together with the existence of sporadic extended opaque Gunn-Peterson troughs, has started to provide robust evidence for a late end of hydrogen reionisation. However, low data quality and systematic uncertainties complicate the use of Ly-$\alpha$ transmission as a precision probe of reionisation's end stages. In this paper, we assemble a sample of 67 quasar sightlines at $z>5.5$ with high signal-to-noise ratios of $>10$ per $15$ km s$^-1$ spectral pixel, relying largely on the new XQR-30 quasar sample. XQR-30 is a large program on VLT/X-Shooter which obtained deep (SNR $>20$ per pixel) spectra of 30 quasars at $z>5.7$. We carefully account for systematics in continuum reconstruction, instrumentation, and contamination by damped Ly-$\alpha$ systems. We present improved measurements of the mean Ly-$\alpha$ transmission over $4.9<z<6.1$. Using all known systematics in a forward modelling analysis, we find excellent agreement between the observed Ly-$\alpha$ transmission distributions and the homogeneous-UVB simulations Sherwood and Nyx up to $złeq5.2$ ($<1 \sigma$), and mild tension ($2.5 \sigma$) at $z=5.3$. Homogeneous UVB models are ruled out by excess Ly-$\alpha$ transmission scatter at $z\geq5.4$ with high confidence ($>3.5 \sigma$). Our results indicate that reionisation-related fluctuations, whether in the UVB, residual neutral hydrogen fraction, and/or IGM temperature, persist in the intergalactic medium until $z=5.3$ ($t=1.1$ Gyr after the Big Bang). This is further evidence for a late end to reionisation.

@misc{bosman2021hydrogen, abstract = {The presence of excess scatter in the Ly-$\alpha$ forest at $z\sim 5.5$, together with the existence of sporadic extended opaque Gunn-Peterson troughs, has started to provide robust evidence for a late end of hydrogen reionisation. However, low data quality and systematic uncertainties complicate the use of Ly-$\alpha$ transmission as a precision probe of reionisation's end stages. In this paper, we assemble a sample of 67 quasar sightlines at $z>5.5$ with high signal-to-noise ratios of $>10$ per $\leq 15$ km s$^{-1}$ spectral pixel, relying largely on the new XQR-30 quasar sample. XQR-30 is a large program on VLT/X-Shooter which obtained deep (SNR $>20$ per pixel) spectra of 30 quasars at $z>5.7$. We carefully account for systematics in continuum reconstruction, instrumentation, and contamination by damped Ly-$\alpha$ systems. We present improved measurements of the mean Ly-$\alpha$ transmission over $4.9<z<6.1$. Using all known systematics in a forward modelling analysis, we find excellent agreement between the observed Ly-$\alpha$ transmission distributions and the homogeneous-UVB simulations Sherwood and Nyx up to $z\leq5.2$ ($<1 \sigma$), and mild tension ($\sim 2.5 \sigma$) at $z=5.3$. Homogeneous UVB models are ruled out by excess Ly-$\alpha$ transmission scatter at $z\geq5.4$ with high confidence ($>3.5 \sigma$). Our results indicate that reionisation-related fluctuations, whether in the UVB, residual neutral hydrogen fraction, and/or IGM temperature, persist in the intergalactic medium until $z=5.3$ ($t=1.1$ Gyr after the Big Bang). This is further evidence for a late end to reionisation.}, added-at = {2021-08-10T08:33:57.000+0200}, author = {Bosman, Sarah E. I. and Davies, Frederick B. and Becker, George D. and Keating, Laura C. and Davies, Rebecca L. and Zhu, Yongda and Eilers, Anna-Christina and D'Odorico, Valentina and Bian, Fuyan and Bischetti, Manuela and Cristiani, Stefano V. and Fan, Xiaohui and Farina, Emanuele P. and Haehnelt, Martin G. and Kulkarni, Girish and Mesinger, Andrei and Meyer, Romain A. and Onoue, Masafusa and Pallottini, Andrea and Qin, Yuxiang and Ryan-Weber, Emma and Schindler, Jan-Torge and Walter, Fabian and Wang, Feige and Yang, Jinyi}, biburl = {https://www.bibsonomy.org/bibtex/2253aa83e3b9c444d24b0a098c9b00bb6/gpkulkarni}, description = {Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample}, interhash = {4312703e83c729d58cda7d4bff1d0688}, intrahash = {253aa83e3b9c444d24b0a098c9b00bb6}, keywords = {library}, note = {cite arxiv:2108.03699Comment: Submitted to MNRAS. 22 pages, 17 figures}, timestamp = {2021-08-10T08:33:57.000+0200}, title = {Hydrogen reionisation ends by $z=5.3$: Lyman-$\alpha$ optical depth measured by the XQR-30 sample}, url = {http://arxiv.org/abs/2108.03699}, year = 2021 }