Observations of the Lyman series forest towards the redshift 7.1 quasar ULAS J1120+0641
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Published version
Author(s)
Type
Journal Article
Abstract
We present a 30 h integration Very Large Telescope X-shooter spectrum of the Lyman series forest towards the z = 7.084 quasar ULAS J1120+0641. The only detected transmission at S/N > 5 is confined to seven narrow spikes in the Lyα forest, over the redshift range 5.858 <z < 6.122, just longward of the wavelength of the onset of the Lyβ forest. There is also a possible detection of one further unresolved spike in the Lyβ forest at z = 6.854, with S/N = 4.5. We also present revised Hubble Space Telescope F814W photometry of the source. The summed flux from the transmission spikes is in agreement with the F814W photometry, so all the transmission in the Lyman series forest may have been detected. There is a Gunn-Peterson (GP) trough in the Lyα forest from z = 6.122 all the way to the quasar near zone at z = 7.04. The trough, of comoving length 240 h-1 Mpc, is over twice as long as the next longest known GP trough. We combine the spectroscopic and photometric results to constrain the evolution of the Lyα effective optical depth (τGPeff) with redshift, extending a similar analysis by Simpson et al. We find τGPeff ∝ (1 + z)ξ where ξ = 11.2+ 0.4-0.6, for z > 5.5. The data nevertheless provide only a weak limit on the volume-weighted intergalactic medium (IGM) hydrogen neutral fraction at z ~ 6.5, xH i > 10-4, similar to limits at redshift z ~ 6 from less distant quasars. The new observations cannot extend measurements of the neutral fraction of the IGM to higher values because absorption in the Lyα forest is already saturated near z ~ 6. For higher neutral fractions, other methods such as measuring the red damping wing of the IGM will be required.
Date Issued
2017-05-01
Date Acceptance
2017-02-09
Citation
Astronomy and Astrophysics: a European journal, 2017, 601
ISSN
0004-6361
Publisher
EDP Sciences
Journal / Book Title
Astronomy and Astrophysics: a European journal
Volume
601
Copyright Statement
© 2017 ESO
Sponsor
Science and Technology Facilities Council
Science and Technology Facilities Council (STFC)
The Leverhulme Trust
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000402313500016&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
ST-N000838
ST/N000838/1
RF-2013-473
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
cosmology: observations
quasars: individual: ULAS J1120+0641
quasars: absorption lines
dark ages,reionization,first stars
DIGITAL SKY SURVEY
NEUTRAL HYDROGEN
ADVANCED CAMERA
ALPHA FOREST
REIONIZATION
DISCOVERY
Z-SIMILAR-TO-6
EVOLUTION
GALAXIES
SPECTRUM
astro-ph.CO
astro-ph.CO
astro-ph.GA
0201 Astronomical and Space Sciences
Astronomy & Astrophysics
Publication Status
Published
Article Number
ARTN A16
Date Publish Online
2017-04-21