He II Ly{beta} GUNN-PETERSON ABSORPTION: NEW HST OBSERVATIONS AND THEORETICAL EXPECTATIONS

Syphers, David; Pieri, Matthew; Shull, J Michael; Anderson, Scott F; Zheng, Wei; Kriss, Gerard A; Smith, Britton; Meiksin, Avery; Schneider, Donald P

doi:10.1088/0004-637X/742/2/99

Title: He II Ly{beta} GUNN-PETERSON ABSORPTION: NEW HST OBSERVATIONS AND THEORETICAL EXPECTATIONS

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Abstract

Observations of He II Ly{alpha} Gunn-Peterson troughs have proved to be a valuable probe of the epoch of helium reionization at z {approx} 3. Since this optical depth can become unmeasurably large even for modest He II fractions, various alternate techniques have been proposed to push to higher redshift, and among the more promising is looking at higher-order Lyman-series troughs. We here report four new observations of the He II Ly{beta} trough, including new data on the only sightline with a prior Ly{beta} observation. However, the effective optical depth ratio {tau}{sub eff,{beta}}/{tau}{sub eff,{alpha}} is not simply predicted by f{sub {beta}}{lambda}{sub {beta}}/f{sub {alpha}}{lambda}{sub {alpha}} = 0.16, and we analyze cosmological simulations to find that the correct ratio for helium at z {approx} 3 is {approx_equal}0.35. In one case we infer {tau}{sub eff,{alpha}} > 8.8, strong evidence that helium was not fully reionized at z = 3.2-3.5, in agreement with previous measurements suggesting a later completion of reionization.

Authors:

Syphers, David; Pieri, Matthew; Shull, J Michael ^[1]; Anderson, Scott F ^[2]; Zheng, Wei; Kriss, Gerard A ^[3]; Smith, Britton ^[4]; Meiksin, Avery ^[5]; Schneider, Donald P ^[6]

CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States)
Astronomy Department, University of Washington, Seattle, WA 98195 (United States)
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)
Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)
Scottish Universities Physics Alliance (SUPA), Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)
Department of Physics and Astronomy, Pennsylvania State University, University Park, PA 16802 (United States)

Publication Date:: Thu Dec 01 00:00:00 EST 2011

OSTI Identifier:: 22004621

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 742; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; COMPUTERIZED SIMULATION; COSMOLOGICAL MODELS; GALAXIES; HELIUM; LYMAN LINES; QUASARS; RED SHIFT; ULTRAVIOLET RADIATION

Citation Formats


                    Syphers, David, Pieri, Matthew, Shull, J Michael, Anderson, Scott F, Zheng, Wei, Kriss, Gerard A, Smith, Britton, Meiksin, Avery, Schneider, Donald P, and York, Donald G., E-mail: David.Syphers@colorado.edu. He II Ly{beta} GUNN-PETERSON ABSORPTION: NEW HST OBSERVATIONS AND THEORETICAL EXPECTATIONS.  United States: N. p., 2011. 
        Web.  doi:10.1088/0004-637X/742/2/99.

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                    Syphers, David, Pieri, Matthew, Shull, J Michael, Anderson, Scott F, Zheng, Wei, Kriss, Gerard A, Smith, Britton, Meiksin, Avery, Schneider, Donald P, & York, Donald G., E-mail: David.Syphers@colorado.edu. He II Ly{beta} GUNN-PETERSON ABSORPTION: NEW HST OBSERVATIONS AND THEORETICAL EXPECTATIONS.  United States.  https://doi.org/10.1088/0004-637X/742/2/99

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                    Syphers, David, Pieri, Matthew, Shull, J Michael, Anderson, Scott F, Zheng, Wei, Kriss, Gerard A, Smith, Britton, Meiksin, Avery, Schneider, Donald P, and York, Donald G., E-mail: David.Syphers@colorado.edu. 2011.  
        "He II Ly{beta} GUNN-PETERSON ABSORPTION: NEW HST OBSERVATIONS AND THEORETICAL EXPECTATIONS".  United States.  https://doi.org/10.1088/0004-637X/742/2/99.

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@article{osti_22004621,

  title        = {He II Ly{beta} GUNN-PETERSON ABSORPTION: NEW HST OBSERVATIONS AND THEORETICAL EXPECTATIONS},

  author       = {Syphers, David and Pieri, Matthew and Shull, J Michael and Anderson, Scott F and Zheng, Wei and Kriss, Gerard A and Smith, Britton and Meiksin, Avery and Schneider, Donald P and York, Donald G., E-mail: David.Syphers@colorado.edu},

  abstractNote = {Observations of He II Ly{alpha} Gunn-Peterson troughs have proved to be a valuable probe of the epoch of helium reionization at z {approx} 3. Since this optical depth can become unmeasurably large even for modest He II fractions, various alternate techniques have been proposed to push to higher redshift, and among the more promising is looking at higher-order Lyman-series troughs. We here report four new observations of the He II Ly{beta} trough, including new data on the only sightline with a prior Ly{beta} observation. However, the effective optical depth ratio {tau}{sub eff,{beta}}/{tau}{sub eff,{alpha}} is not simply predicted by f{sub {beta}}{lambda}{sub {beta}}/f{sub {alpha}}{lambda}{sub {alpha}} = 0.16, and we analyze cosmological simulations to find that the correct ratio for helium at z {approx} 3 is {approx_equal}0.35. In one case we infer {tau}{sub eff,{alpha}} > 8.8, strong evidence that helium was not fully reionized at z = 3.2-3.5, in agreement with previous measurements suggesting a later completion of reionization.},

  doi          = {10.1088/0004-637X/742/2/99},

  url          = {https://www.osti.gov/biblio/22004621},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 2,

  volume       = 742,

  place        = {United States},

  year         = {Thu Dec 01 00:00:00 EST 2011},

  month        = {Thu Dec 01 00:00:00 EST 2011}

}

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