How probable is the Lyman-α damping wing in the spectrum of the redshift z = 5.9896 quasar ULAS J0148+0600?
Abstract
The shape of the Ly-α transmission in the near zone of the redshift z=5.9896 quasar ULAS J0148+0600 (hereafter J0148) is consistent with a damping wing arising from an extended neutral hydrogen island in the diffuse intergalactic medium (IGM). Here we use simulations of late-ending reionisation from Sherwood-Relics to assess the expected incidence of quasars with Ly-α and Ly-β absorption similar to the observed J0148 spectrum. We find a late end to reionisation at z=5.3 is a necessary requirement for reproducing a Ly-α damping wing consistent with J0148. This occurs in 3 per cent of our simulated spectra for an IGM neutral fraction x HI=0.14 at z=6. However, using standard assumptions for the ionising photon output of J0148, the a priori probability of drawing a simulated quasar spectrum with a Ly-α damping wing profile and Ly-α near zone size that simultaneously match J0148 is low, p<10-2. This may indicate that the ionising emission from J0148 is variable on timescales t<105\,yr, or alternatively that the Ly-α transmission in the J0148 near zone is impacted by the transverse proximity effect from nearby star-forming galaxies or undetected quasars. We also predict the IGM temperature should be T 4× 104\,K within a few proper Mpc of the Ly-α near zone edge due to recent H\, I and He\, II photo-heating. Evidence for enhanced thermal broadening in the Ly-α absorption near the damping wing edge would provide further evidence that the final stages of reionisation are occurring at z<6.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.