Evidence for reionization at z ∼ 6

Detection of a gunn-peterson trough in a z = 6.28 quasar

Robert H. Becker, Xiaohui Fan, Richard L. White, Michael A. Strauss, Vijay K. Narayanan, Robert H. Lupton, James E. Gunn, James Annis, Neta A. Bahcall, J. Brinkmann, A. J. Connolly, István Csabai, Paul C. Czarapata, Mamoru Doi, Timothy M. Heckman, G. S. Hennessy, Željko Ivezić, G. R. Knapp, Don Q. Lamb, Timothy A. Mckay & 10 others Jeffrey A. Munn, Thomas Nash, Robert Nichol, Jeffrey R. Pier, Gordon T. Richards, Donald P. Schneider, Chris Stoughton, Alexander S. Szalay, Aniruddha R. Thakar, D. G. York

Research output: Contribution to journalArticle

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Abstract

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 Lyα absorption in the spectra of these quasars evolves strongly with redshift. To z ∼ 5.7, the Lyα 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 Å < λ < 8710 Å (5.95 < zabs < 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 Lyα forest region immediately blueward of the Lyα emission line, compared with a drop by a factor of ∼10 at zabs ∼ 5.3. A similar break is seen at Lyβ; because of the decreased oscillator strength of this transition, this allows us to put a considerably stronger limit, τeff > 20, on the optical depth to Lyα 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 Lyα 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.

Original languageEnglish (US)
Pages (from-to)2850-2857
Number of pages8
JournalAstronomical Journal
Volume122
Issue number6
DOIs
StatePublished - Dec 1 2001

Fingerprint

troughs
quasars
trough
intergalactic media
hydrogen
time measurement
optical depth
optical thickness
spectroscopy
line of sight
extrapolation
universe
detection
continuums

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Becker, R. H., Fan, X., White, R. L., Strauss, M. A., Narayanan, V. K., Lupton, R. H., ... York, D. G. (2001). Evidence for reionization at z ∼ 6: Detection of a gunn-peterson trough in a z = 6.28 quasar. Astronomical Journal, 122(6), 2850-2857. https://doi.org/10.1086/324231
Becker, Robert H. ; Fan, Xiaohui ; White, Richard L. ; Strauss, Michael A. ; Narayanan, Vijay K. ; Lupton, Robert H. ; Gunn, James E. ; Annis, James ; Bahcall, Neta A. ; Brinkmann, J. ; Connolly, A. J. ; Csabai, István ; Czarapata, Paul C. ; Doi, Mamoru ; Heckman, Timothy M. ; Hennessy, G. S. ; Ivezić, Željko ; Knapp, G. R. ; Lamb, Don Q. ; Mckay, Timothy A. ; Munn, Jeffrey A. ; Nash, Thomas ; Nichol, Robert ; Pier, Jeffrey R. ; Richards, Gordon T. ; Schneider, Donald P. ; Stoughton, Chris ; Szalay, Alexander S. ; Thakar, Aniruddha R. ; York, D. G. / Evidence for reionization at z ∼ 6 : Detection of a gunn-peterson trough in a z = 6.28 quasar. In: Astronomical Journal. 2001 ; Vol. 122, No. 6. pp. 2850-2857.
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abstract = "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 Lyα absorption in the spectra of these quasars evolves strongly with redshift. To z ∼ 5.7, the Lyα 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 {\AA} < λ < 8710 {\AA} (5.95 < zabs < 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 Lyα forest region immediately blueward of the Lyα emission line, compared with a drop by a factor of ∼10 at zabs ∼ 5.3. A similar break is seen at Lyβ; because of the decreased oscillator strength of this transition, this allows us to put a considerably stronger limit, τeff > 20, on the optical depth to Lyα 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 Lyα 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.",
author = "Becker, {Robert H.} and Xiaohui Fan and White, {Richard L.} and Strauss, {Michael A.} and Narayanan, {Vijay K.} and Lupton, {Robert H.} and Gunn, {James E.} and James Annis and Bahcall, {Neta A.} and J. Brinkmann and Connolly, {A. J.} and Istv{\'a}n Csabai and Czarapata, {Paul C.} and Mamoru Doi and Heckman, {Timothy M.} and Hennessy, {G. S.} and Željko Ivezić and Knapp, {G. R.} and Lamb, {Don Q.} and Mckay, {Timothy A.} and Munn, {Jeffrey A.} and Thomas Nash and Robert Nichol and Pier, {Jeffrey R.} and Richards, {Gordon T.} and Schneider, {Donald P.} and Chris Stoughton and Szalay, {Alexander S.} and Thakar, {Aniruddha R.} and York, {D. G.}",
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Becker, RH, Fan, X, White, RL, Strauss, MA, Narayanan, VK, Lupton, RH, Gunn, JE, Annis, J, Bahcall, NA, Brinkmann, J, Connolly, AJ, Csabai, I, Czarapata, PC, Doi, M, Heckman, TM, Hennessy, GS, Ivezić, Ž, Knapp, GR, Lamb, DQ, Mckay, TA, Munn, JA, Nash, T, Nichol, R, Pier, JR, Richards, GT, Schneider, DP, Stoughton, C, Szalay, AS, Thakar, AR & York, DG 2001, 'Evidence for reionization at z ∼ 6: Detection of a gunn-peterson trough in a z = 6.28 quasar', Astronomical Journal, vol. 122, no. 6, pp. 2850-2857. https://doi.org/10.1086/324231

Evidence for reionization at z ∼ 6 : Detection of a gunn-peterson trough in a z = 6.28 quasar. / Becker, Robert H.; Fan, Xiaohui; White, Richard L.; Strauss, Michael A.; Narayanan, Vijay K.; Lupton, Robert H.; Gunn, James E.; Annis, James; Bahcall, Neta A.; Brinkmann, J.; Connolly, A. J.; Csabai, István; Czarapata, Paul C.; Doi, Mamoru; Heckman, Timothy M.; Hennessy, G. S.; Ivezić, Željko; Knapp, G. R.; Lamb, Don Q.; Mckay, Timothy A.; Munn, Jeffrey A.; Nash, Thomas; Nichol, Robert; Pier, Jeffrey R.; Richards, Gordon T.; Schneider, Donald P.; Stoughton, Chris; Szalay, Alexander S.; Thakar, Aniruddha R.; York, D. G.

In: Astronomical Journal, Vol. 122, No. 6, 01.12.2001, p. 2850-2857.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Evidence for reionization at z ∼ 6

T2 - Detection of a gunn-peterson trough in a z = 6.28 quasar

AU - Becker, Robert H.

AU - Fan, Xiaohui

AU - White, Richard L.

AU - Strauss, Michael A.

AU - Narayanan, Vijay K.

AU - Lupton, Robert H.

AU - Gunn, James E.

AU - Annis, James

AU - Bahcall, Neta A.

AU - Brinkmann, J.

AU - Connolly, A. J.

AU - Csabai, István

AU - Czarapata, Paul C.

AU - Doi, Mamoru

AU - Heckman, Timothy M.

AU - Hennessy, G. S.

AU - Ivezić, Željko

AU - Knapp, G. R.

AU - Lamb, Don Q.

AU - Mckay, Timothy A.

AU - Munn, Jeffrey A.

AU - Nash, Thomas

AU - Nichol, Robert

AU - Pier, Jeffrey R.

AU - Richards, Gordon T.

AU - Schneider, Donald P.

AU - Stoughton, Chris

AU - Szalay, Alexander S.

AU - Thakar, Aniruddha R.

AU - York, D. G.

PY - 2001/12/1

Y1 - 2001/12/1

N2 - 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 Lyα absorption in the spectra of these quasars evolves strongly with redshift. To z ∼ 5.7, the Lyα 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 Å < λ < 8710 Å (5.95 < zabs < 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 Lyα forest region immediately blueward of the Lyα emission line, compared with a drop by a factor of ∼10 at zabs ∼ 5.3. A similar break is seen at Lyβ; because of the decreased oscillator strength of this transition, this allows us to put a considerably stronger limit, τeff > 20, on the optical depth to Lyα 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 Lyα 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.

AB - 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 Lyα absorption in the spectra of these quasars evolves strongly with redshift. To z ∼ 5.7, the Lyα 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 Å < λ < 8710 Å (5.95 < zabs < 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 Lyα forest region immediately blueward of the Lyα emission line, compared with a drop by a factor of ∼10 at zabs ∼ 5.3. A similar break is seen at Lyβ; because of the decreased oscillator strength of this transition, this allows us to put a considerably stronger limit, τeff > 20, on the optical depth to Lyα 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 Lyα 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.

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DO - 10.1086/324231

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Becker RH, Fan X, White RL, Strauss MA, Narayanan VK, Lupton RH et al. Evidence for reionization at z ∼ 6: Detection of a gunn-peterson trough in a z = 6.28 quasar. Astronomical Journal. 2001 Dec 1;122(6):2850-2857. https://doi.org/10.1086/324231