VLT/X-SHOOTER & Keck/ESI spectra of z~5 QSOs

Using spectra of 55 QSOs at z_em_>5.5, including new data from the XQR-30 VLT Large Programme, we identify gaps in the Ly{alpha} forest where the transmission averaged over 1 comoving h^-1^ Mpc bins falls below 5%. Nine ultralong (L>80h^-1^Mpc) dark gaps are identified at z<6.

In addition, we quantify the fraction of QSO spectra exhibiting gaps longer than 30h^-1^Mpc, F_30_, as a function of redshift. We measure F_30_~0.9, 0.6, and 0.15 at z=6.0, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to z~5.3. Comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six.