Статья

Evidence for Reionization at [ITAL][CLC]z[/CLC][/ITAL] ∼ 6: Detection of a Gunn-Peterson Trough in a [ITAL][CLC]z[/CLC][/ITAL] = 6.28 Quasar

R. H. BeckerDepartment of Physics, University of California at Davis, Davis, CA 95616Xiaohui FanInstitute for Advanced Study, Olden Lane, Princeton, NJ 08540R. L. WhiteSpace Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218Michael A. StraussPrinceton University Observatory, Princeton, NJ 08544Vijay K. NarayananPrinceton University Observatory, Princeton, NJ 08544Robert H. LuptonPrinceton University Observatory, Princeton, NJ 08544James E. GunnPrinceton University Observatory, Princeton, NJ 08544James AnnisFermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510Neta A. BahcallPrinceton University Observatory, Princeton, NJ 08544J. BrinkmannAndrew J. ConnollyDepartment of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260István CsabaiDepartment of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218Paul C. CzarapataFermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510Mamoru DoiDepartment of Astronomy and Research Center for the Early Universe, School of Science, University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, JapanTimothy M. HeckmanDepartment of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218G. S. HennessyUS Naval Observatory, 3450 Massachusetts Avenue, NW, Washington, DC 20392-5420Željko IvezićPrinceton University Observatory, Princeton, NJ 08544G. R. KnappPrinceton University Observatory, Princeton, NJ 08544D. Q. LambAstronomy and Astrophysics Center, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637Timothy A. McKayDepartment of Physics, University of Michigan, 500 East University, Ann Arbor, MI 48109Jeffrey A. MunnUS Naval Observatory, Flagstaff Station, P.O. Box 1149, Flagstaff, AZ 86002-1149Thomas NashFermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510Robert C. NicholDepartment of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15232Jeffrey R. PierUS Naval Observatory, Flagstaff Station, P.O. Box 1149, Flagstaff, AZ 86002-1149Gordon T. RichardsDepartment of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802Donald P. SchneiderDepartment of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802Chris StoughtonFermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510Alexander S. SzalayDepartment of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218Aniruddha R. ThakarDepartment of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218Donald G. YorkAstronomy and Astrophysics Center, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637

2001en

ABI

Аннотация

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 similar to 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 Angstrom < <lambda> < 8710 <Angstrom> (5.95 < z(abs) < 6.16), consistent with zero flux. Thus the flux level drops by a factor of greater than 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 similar to 10 at z(abs) similar to 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 similar to 5 to 6, and the universe is approaching the reionization epoch at z similar to 6.

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Идентификаторы

DOI: 10.1086/324231

Цитирования и источники

Цитирований: 2Использованных источников: 0

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