Journal article
Evidence for Reionization at z ~ 6: Detection of a Gunn-Peterson Trough in a z=6.28 Quasar
The Astronomical journal, v 122(6), pp 2850-2857
06 Aug 2001
Abstract
Astron.J. 122 (2001) 2850 We present moderate resolution Keck spectroscopy of quasars at z=5.82, 5.99
and 6.28, discovered by the Sloan Digital Sky Survey (SDSS). We find that the
Ly Alpha absorption in the spectra of these quasars evolves strongly with
redshift. To z~5.7, the Ly Alpha absorption evolves as expected from an
extrapolation from lower redshifts. However, in the highest redshift object,
SDSSp J103027.10+052455.0 (z=6.28), the average transmitted flux is
0.0038+-0.0026 times that of the continuum level over 8450 A < lambda < 8710 A
(5.95<z(abs)<6.16), consistent with zero flux. Thus the flux level drops by a
factor of >150, and is consistent with zero flux in the Ly Alpha forest region
immediately blueward of the Ly Alpha emission line, compared with a drop by a
factor of ~10 at z(abs)~5.3. A similar break is seen at Ly Beta; because of the
decreased oscillator strength of this transition, this allows us to put a
considerably stronger limit, tau(eff) > 20, on the optical depth to Ly Alpha
absorption at z=6.
This is a clear detection of a complete Gunn-Peterson trough, caused by
neutral hydrogen in the intergalactic medium. Even a small neutral hydrogen
fraction in the intergalactic medium would result in an undetectable flux in
the Ly Alpha forest region. Therefore, the existence of the Gunn-Peterson
trough by itself does not indicate that the quasar is observed prior to the
reionization epoch. However, the fast evolution of the mean absorption in these
high-redshift quasars suggests that the mean ionizing background along the line
of sight to this quasar has declined significantly from z~5 to 6, and the
universe is approaching the reionization epoch at z~6.
Metrics
Details
- Title
- Evidence for Reionization at z ~ 6: Detection of a Gunn-Peterson Trough in a z=6.28 Quasar
- Creators
- Robert H Becker - Lawrence Livermore National LaboratoryXiaohui Fan - EarthTech InternationalRichard L White - Space Telescope Science InstituteMichael A Strauss - Princeton UniversityVijay K Narayanan - Princeton UniversityRobert H Lupton - Princeton UniversityJames E Gunn - Princeton UniversityJames Annis - FermilabNeta A Bahcall - Princeton UniversityJ Brinkmann - New Mexico State UniversityA. J Connolly - University of PittsburghIstvan Csabai - Eötvös Loránd UniversityPaul C Czarapata - FermilabMamoru Doi - University of TokyoTimothy M Heckman - Johns Hopkins UniversityG. S Hennessy - United States Naval ObservatoryZeljko Ivezic - Princeton UniversityG. R Knapp - Princeton UniversityDon Q Lamb - University of ChicagoTimothy A McKay - University of Michigan–Ann ArborJeffrey A Munn - United States Department of the NavyThomas Nash - FermilabRobert Nichol - Carnegie Mellon UniversityJeffrey R Pier - United States Department of the NavyGordon T Richards - Pennsylvania State UniversityDonald P Schneider - Pennsylvania State UniversityChris Stoughton - FermilabAlexander S Szalay - Johns Hopkins UniversityAnirudda R ThakarD. G York - University of Chicago
- Publication Details
- The Astronomical journal, v 122(6), pp 2850-2857
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Web of Science ID
- WOS:000172932200004
- Scopus ID
- 2-s2.0-0042117667
- Other Identifier
- 991019201495204721
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Astronomy & Astrophysics