TY - JOUR
T1 - Constraints on reionization from the thermal history of the intergalactic medium
AU - Theuns, Tom
AU - Schaye, Joop
AU - Zaroubi, Saleem
AU - Kim, Tae Sun
AU - Tzanavaris, Panayiotis
AU - Carswell, Bob
PY - 2002/3/10
Y1 - 2002/3/10
N2 - The temperature of the diffuse, photoheated intergalactic medium (IGM) depends on its reionization history because the thermal timescales are long. The widths of the hydrogen Lyα absorption lines seen in the spectra of distant quasars that arise in the IGM can be used to determine its temperature. We use a wavelet analysis of the Lyα forest region of quasar spectra to demonstrate that there is a relatively sudden increase in the line widths between redshifts z ≈ 3.5 and 3.0, which we associate with entropy injection resulting from the reionization of He II. The subsequent falloff in temperature after z ≈ 3.5 is consistent with a thermal evolution dominated by adiabatic expansion. If, as expected, the temperature also drops rapidly after hydrogen reionization, then the high temperatures inferred from the line widths before He II reionization imply that hydrogen reionization occurred below redshift z = 9.
AB - The temperature of the diffuse, photoheated intergalactic medium (IGM) depends on its reionization history because the thermal timescales are long. The widths of the hydrogen Lyα absorption lines seen in the spectra of distant quasars that arise in the IGM can be used to determine its temperature. We use a wavelet analysis of the Lyα forest region of quasar spectra to demonstrate that there is a relatively sudden increase in the line widths between redshifts z ≈ 3.5 and 3.0, which we associate with entropy injection resulting from the reionization of He II. The subsequent falloff in temperature after z ≈ 3.5 is consistent with a thermal evolution dominated by adiabatic expansion. If, as expected, the temperature also drops rapidly after hydrogen reionization, then the high temperatures inferred from the line widths before He II reionization imply that hydrogen reionization occurred below redshift z = 9.
KW - Cosmology: observations
KW - Cosmology: theory
KW - Galaxies: formation
KW - Intergalactic medium
KW - Quasars: absorption lines
UR - http://www.scopus.com/inward/record.url?scp=0041328752&partnerID=8YFLogxK
U2 - 10.1086/339998
DO - 10.1086/339998
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AN - SCOPUS:0041328752
SN - 0004-637X
VL - 567
SP - L103-L106
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
ER -