期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 757, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/757/2/L30
关键词
intergalactic medium; quasars: absorption lines
资金
- W. M. Keck Foundation
- US National Science Foundation [AST-0606912, AST-0908805]
- John D. and Catherine T. MacArthur Foundation
- Peter and Patricia Gruber Foundation
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [0908805] Funding Source: National Science Foundation
- STFC [ST/J001538/1, ST/J000647/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/J000647/1, ST/J001538/1, ST/H00243X/1] Funding Source: researchfish
We present new measurements of the temperature-density (T-rho) relation for neutral hydrogen in the 2.0 < z < 2.8 intergalactic medium (IGM) using a sample of similar to 6000 individual Hi absorbers fitted with Voigt profiles constrained in all cases by multiple Lyman series transitions. We find model-independent evidence for a positive correlation between the column density of HI (N-HI) and the minimum observed velocity width of absorbers (b(min)). With minimal interpretation, this implies that the T-rho relation in the IGM is not inverted, contrary to many recent studies. Fitting b(min) as a function of N-HI results in line-width-column-density dependence of the form b(min) = b(0)(N-HI/N-HI,N-0)(Gamma-1) with a minimum line width at mean density (rho/(rho) over bar = 1, N-HI,N-0 = 10(13.6) cm(-2)) of b(0) = 17.9 +/- 0.2 kms(-1) and a power-law index of (Gamma - 1) = 0.15 +/- 0.02. Using analytic arguments, these measurements imply an equation of state for the IGM at < z > = 2.4 of the form T = T-0 (rho/(rho) over bar)(gamma-1) with a temperature at mean density of T-0 = [1.94 +/- 0.05] x 10(4) K and a power-law index (gamma - 1) = 0.46 +/- 0.05.
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