How neutral is the intergalactic medium surrounding the redshift z = 7.085 quasar ULAS J1120+0641?
Article first published online: 21 JUL 2011
© 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS
Monthly Notices of the Royal Astronomical Society: Letters
Volume 416, Issue 1, pages L70–L74, September 2011
How to Cite
Bolton, J. S., Haehnelt, M. G., Warren, S. J., Hewett, P. C., Mortlock, D. J., Venemans, B. P., McMahon, R. G. and Simpson, C. (2011), How neutral is the intergalactic medium surrounding the redshift z = 7.085 quasar ULAS J1120+0641?. Monthly Notices of the Royal Astronomical Society: Letters, 416: L70–L74. doi: 10.1111/j.1745-3933.2011.01100.x
- Issue published online: 11 AUG 2011
- Article first published online: 21 JUL 2011
- Accepted 2011 June 23. Received 2011 June 22; in original form 2011 May 2
- dark ages, reionization, first stars;
- intergalactic medium;
- quasars: absorption lines
The quasar ULAS J1120+0641 at redshift z = 7.085 has a highly ionized near zone which is smaller than those around quasars of similar luminosity at z ≃ 6. The spectrum also exhibits evidence for a damping wing extending redward of the systemic Lyα redshift. We use radiative transfer simulations in a cosmological context to investigate the implications for the ionization state of the inhomogeneous intergalactic medium (IGM) surrounding this quasar. Our simulations show that the transmission profile is consistent with an IGM in the vicinity of the quasar with a volume averaged H i fraction of and that ULAS J1120+0641 has been bright for 106–107 yr. The observed spectrum is also consistent with smaller IGM neutral fractions, , if a damped Lyα system in an otherwise highly ionized IGM lies within 5 proper Mpc of the quasar. This is, however, predicted to occur in only ∼5 per cent of our simulated sightlines for a bright phase of 106–107 yr. Unless ULAS J1120+0641 grows during a previous optically obscured phase, the low age inferred for the quasar adds to the theoretical challenge of forming a 2 × 109 M⊙ black hole at this high redshift.