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Title: A New Measurement of the Temperature–density Relation of the IGM from Voigt Profile Fitting

Journal Article · · The Astrophysical Journal (Online)
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5];  [6];  [7]
  1. Max-Planck-Inst. für Astronomie, Heidelberg (Germany); Univ. of Heidelberg, Heidelberg (Germany). International Max Planck Research School for Astronomy & Cosmic Physics
  2. Max-Planck-Inst. für Astronomie, Heidelberg (Germany); Univ. of Heidelberg, Heidelberg (Germany). International Max Planck Research School for Astronomy & Cosmic Physics; Univ. of California, Santa Barbara, CA (United States). Physics Dept.
  3. Max-Planck-Inst. für Astronomie, Heidelberg (Germany); Univ. of California, Santa Barbara, CA (United States). Physics Dept.
  4. Max-Planck-Inst. für Astronomie, Heidelberg (Germany)
  5. Saint Michaels College, Colchester, VT (United States). Dept. of Chemistry and Physics
  6. Max-Planck-Inst. für Astronomie, Heidelberg (Germany); Kavli Inst. for Cosmology and Inst. of Astronomy, Cambridge (United Kingdom); Inst. of Astronomy, Cambridge (United Kingdom)
  7. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
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We decompose the Lyman-α (Lyα) forest of an extensive sample of 75 high signal-to-noise ratio and high-resolution quasar spectra into a collection of Voigt profiles. Absorbers located near caustics in the peculiar velocity field have the smallest Doppler parameters, resulting in a low-b cutoff in the b- distribution set primarily by the thermal state of the intergalactic medium (IGM). We fit this cutoff as a function of redshift over the range 2.0 ≤ z ≤ 3.4, which allows us to measure the evolution of the IGM temperature-density (T = T0(ρ/ρ0)γ-1) relation parameters T 0 and γ. We calibrate our measurements against mock Lyα forest data generated using 26 hydrodynamic simulations with different thermal histories from the THERMAL suite, also encompassing different values of the IGM pressure smoothing scale. We adopt a forward-modeling approach and self-consistently apply the same algorithms to both data and simulations, propagating both statistical and modeling uncertainties via Monte Carlo. The redshift evolution of T 0 (γ) shows a suggestive peak (dip) at z = 2.9 (z = 3). Our measured evolution of T 0 and γ is generally in good agreement with previous determinations in the literature. Both the peak in the evolution of T 0 at z = 2.8, as well as the high temperatures T0 ≃ 15,000-20,000 K that we observe at 2.4 < z < 3.4, strongly suggest that a significant episode of heating occurred after the end of H I reionization, which was most likely the cosmic reionization of He II.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1493263
Journal Information:
The Astrophysical Journal (Online), Vol. 865, Issue 1; ISSN 1538-4357
Publisher:
Institute of Physics (IOP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 42 works
Citation information provided by
Web of Science

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The photoheating of the intergalactic medium in synthesis models of the UV background text January 2015
Exploring the thermal state of the low-density intergalactic medium at $z$ = 3 with an ultrahigh signal-to-noise QSO spectrum text January 2017
The effect of stellar and AGN feedback on the low redshift Lyman-α forest in the Sherwood simulation suite text January 2017
A new measurement of the intergalactic temperature at z ∼ 2.55–2.95 text January 2018
The effect of stellar and AGN feedback on the low-redshift Lyman a forest in the Sherwood simulation suite text January 2017
An improved measurement of the flux distribution of the Ly-alpha forest in QSO absorption spectra: the effect of continuum fitting, metal contamination and noise properties text January 2007
Possible evidence for an inverted temperature-density relation in the intergalactic medium from the flux distribution of the Lyman-alpha forest text January 2007
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The imprint of inhomogeneous HeII reionization on the HI and HeII Ly-alpha forest text January 2013
The one-dimensional Ly-alpha forest power spectrum from BOSS text January 2013
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Cited By (18)

The Goldilocks problem of the quasar contribution to reionization journal December 2018
Evolution of the AGN UV luminosity function from redshift 7.5 journal June 2019
New synthesis models of consistent extragalactic background light over cosmic time journal January 2019
Consistent modelling of the meta-galactic UV background and the thermal/ionization history of the intergalactic medium journal January 2019
Local photoionization feedback effects on galaxies journal September 2019
Effect of non-equilibrium ionization on derived physical conditions of the high-z intergalactic medium journal October 2019
The power spectrum of the Lyman-α Forest at z < 0.5 journal February 2019
Measuring the temperature and profiles of Ly α absorbers journal December 2019
New Constraints on IGM Thermal Evolution from the Ly α Forest Power Spectrum journal February 2019
Revealing Reionization with the Thermal History of the Intergalactic Medium: New Constraints from the Ly α Flux Power Spectrum journal February 2019
The Evolution of the He ii-ionizing Background at Redshifts 2.3 < z < 3.8 Inferred from a Statistical Sample of 24 HST /COS He ii Ly α Absorption Spectra journal April 2019
A Novel Statistical Method for Measuring the Temperature–Density Relation in the IGM Using the b – N H i Distribution of Absorbers in the Ly α Forest journal May 2019
Space Densities and Emissivities of Active Galactic Nuclei at z > 4 journal October 2019
Thermal State of the Intergalactic Medium at z ∼ 2–4 journal December 2019
Consistent modelling of the meta-galactic UV background and the thermal/ionization history of the intergalactic medium text January 2019
New synthesis models of consistent extragalactic background light over cosmic time text January 2018
Local photoionization feedback effects on galaxies text January 2019
Thermal state of the intergalactic medium at $z\sim2-4$ text January 2019

Figures / Tables (30)

Figure 1(p. 3)figure Figure 1
Table 1(p. 4)table Table 1
Figure 2(p. 5)figure Figure 2
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Table 3(p. 17)table Table 3
Figure 16(p. 18)figure Figure 16
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Table 4(p. 21)table Table 4
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Figure 23(p. 23)figure Figure 23
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Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
cosmology: observations
dark ages
reionization
first stars
intergalactic medium
quasars: absorption lines