TY - JOUR
T1 - A feature at z ∼ 3.2 in the evolution of the Lyα forest optical depth
AU - Bernardi, Mariangela
AU - Sheth, Ravi K.
AU - SubbaRao, Mark
AU - Richards, Gordon T.
AU - Burles, Scott
AU - Connolly, Andrew J.
AU - Frieman, Joshua
AU - Nichol, Robert
AU - Schaye, Joop
AU - Schneider, Donald P.
AU - Vanden Berk, Daniel E.
AU - York, Donald G.
AU - Brinkmann, J.
AU - Lamb, Don Q.
N1 - Copyright:
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
PY - 2003/1
Y1 - 2003/1
N2 - The effective optical depth in the Lyα forest region of 1061 low-resolution QSO spectra drawn from the SDSS database decreases with decreasing redshift over the range 2.5 ≤ z ≤ 4. Although the evolution is relatively smooth, τeff ∝ (1 + z)3.8±0.2, at z ∼ 3.2 the effective optical depth decreases suddenly by about 10% with respect to this smoother evolution. It climbs back to the original smooth scaling again by z ∼ 2.9. We describe two techniques, one of which is new, for quantifying this evolution that give consistent results. A variety of tests show that the feature is not likely to be a consequence of how the QSO sample was selected nor the result of flux calibration or other systematic effects. Other authors have argued that, at this same epoch, the temperature of the IGM also shows a departure from an otherwise smooth decrease with time. These features in the evolution of the temperature and the optical depth are signatures of the reionization of Hen.
AB - The effective optical depth in the Lyα forest region of 1061 low-resolution QSO spectra drawn from the SDSS database decreases with decreasing redshift over the range 2.5 ≤ z ≤ 4. Although the evolution is relatively smooth, τeff ∝ (1 + z)3.8±0.2, at z ∼ 3.2 the effective optical depth decreases suddenly by about 10% with respect to this smoother evolution. It climbs back to the original smooth scaling again by z ∼ 2.9. We describe two techniques, one of which is new, for quantifying this evolution that give consistent results. A variety of tests show that the feature is not likely to be a consequence of how the QSO sample was selected nor the result of flux calibration or other systematic effects. Other authors have argued that, at this same epoch, the temperature of the IGM also shows a departure from an otherwise smooth decrease with time. These features in the evolution of the temperature and the optical depth are signatures of the reionization of Hen.
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U2 - 10.1086/344945
DO - 10.1086/344945
M3 - Article
AN - SCOPUS:0042260734
SN - 0004-6256
VL - 125
SP - 32
EP - 52
JO - Astronomical Journal
JF - Astronomical Journal
IS - 1 1765
ER -