Linear Gas Dynamics in the Expanding Universe

Gnedin, Nickolay Y.; Baker, Emily J.; Bethell, Thomas J.; Drosback, Meredith M.; Harford, A. Gayler; Hicks, A. K.; Jensen, Adam G.; Keeney, Brian A.; Kelso, Christopher M.; Neyrinck, Mark C.; Pollack, S. E.; Vliet, Timothy P. van

doi:10.1086/345424

Cited by 28 publications

(38 citation statements)

References 10 publications

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“…Gnedin (2000) extended the usefulness of the filtering mass to the fully non‐linear regime by showing that it is also related to another characteristic mass scale – the largest halo mass for which the gas content is substantially suppressed compared to the cosmic fraction. As we show below, if we follow previous calculations (Gnedin & Hui 1998; Gnedin 2000; Gnedin et al 2003), we find a characteristic mass at high redshift of ∼10 6 M ⊙ , approximately constant at z ≳ 60 and decreasing only slowly with time afterwards. This is somewhat larger than the mass scale of the first objects and suggests a potent effect on the formation of the first objects.…”

Section: Introductionsupporting

confidence: 86%

The formation and gas content of high-redshift galaxies and minihaloes

Naoz¹,

Barkana²

2007

Monthly Notices of the Royal Astronomical Society

118

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We investigate the suppression of the baryon density fluctuations compared to the dark matter in the linear regime. Previous calculations predict that the suppression occurs up to a characteristic mass scale of ∼106 M⊙, which suggests that pressure has a central role in determining the properties of the first luminous objects at early times. We show that the expected characteristic mass scale is in fact substantially lower (by a factor of ∼3–10, depending on redshift), and thus the effect of baryonic pressure on the formation of galaxies up to reionization is only moderate. This reduction in the characteristic mass scale is a result of including the fact that the baryons have smoother initial conditions than the dark matter. This smoothing is due to the aftereffects of the coupling with the radiation before recombination. This yields lower pressure gradients than previous estimations in the period from cosmic recombination to z∼ 200, after which the gas cooled down adiabatically and the pressure dropped. At z∼ 10 the suppression of the baryon fluctuations is still sensitive to the history of pressure in this high‐redshift era. We calculate the fraction of the cosmic gas that is in minihaloes and find that it is substantially higher than would be expected with the previously estimated characteristic mass. Expanding our investigation to the non‐linear regime, we calculate in detail the spherical collapse of high‐redshift objects in a Λ cold dark matter universe. We include the gravitational contributions of the baryons and radiation and the memory of their kinematic coupling before recombination. We use our results to predict a more accurate halo mass function as a function of redshift.

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Section: Introductionsupporting

confidence: 86%

The formation and gas content of high-redshift galaxies and minihaloes

Naoz¹,

Barkana²

2007

Monthly Notices of the Royal Astronomical Society

118

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“…We take the k ‐space filter W b to be a Gaussian. Such a filter gives a good fit to the gas fluctuations over a wide range of wavenumber (Gnedin et al 2003; see also Zaroubi et al 2006). In principle, we expect k F to depend on the physical state of the IGM.…”

Section: Generating Mock Quasar Spectramentioning

confidence: 99%

The probability distribution function of the Lyman transmitted flux from a sample of Sloan Digital Sky Survey quasars

Desjacques

Nusser

Sheth

2007

Monthly Notices of the Royal Astronomical Society

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We present a measurement of the probability distribution function (PDF) of the transmitted flux in the Lyman α (Lyα) forest from a sample of 3492 quasars included in the Sloan Digital Sky Survey data release 3 (SDSS DR3). Our intention is to investigate the sensitivity of the Lyα flux PDF as measured from low‐resolution and low signal‐to‐noise ratio data to a number of systematic errors such as uncertainties in the mean flux, continuum and noise estimate. The quasar continuum is described by the superposition of a power law and emission lines. We perform a power‐law continuum fitting on a spectrum‐by‐spectrum basis, and obtain an average continuum slope of αν= 0.59 ± 0.36 in the redshift range 2.5 < z < 3.5. We take into account that the variation in the continuum indices increases the mean flux by 3 and 7 per cent at z= 3 and 2.4, respectively, as compared to the values inferred with a single (mean) continuum slope. We compare our measurements to the PDF obtained with mock lognormal spectra, whose statistical properties have been constrained to match the observed Lyα flux PDF and power spectrum of high‐resolution data. Using our power‐law continuum fitting and the SDSS pipeline noise estimate yields a poor agreement between the observed and mock PDFs. Allowing for a break in the continuum slope and, more importantly, for residual scatter in the continuum level substantially improves the agreement. A decrease of ∼10–15 per cent in the mean quasar continuum with a typical rms variance at the 20 per cent level can account for the data, provided that the noise excess correction is no larger than ≲10 per cent.

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“…This effect can be modelled by a window function W g ( k ) such that P g ( k ) = W 2 g ( k ) P DM ( k ), which can be choose as a Gaussian window function (see e.g. Hui & Gnedin 1997; Gnedin 2000; Gnedin et al 2003). In an adiabatically evolving universe, gas traces dark matter down to very small scales and W g would be effectively unity.…”

Section: The Analytical Modelmentioning

confidence: 99%

Precision era of the kinetic Sunyaev-Zel'dovich effect: simulations, analytical models and observations and the power to constrain reionization

Zhang

Pen

Trac

2004

Monthly Notices of the Royal Astronomical Society

123

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The kinetic Sunyaev–Zel'dovich effect, which is the dominant cosmic microwave background (CMB) source at arcmin scales and ν∼ 217 GHz, probes the ionized gas peculiar momentum up to the epoch of reionization and is a sensitive measure of the reionization history. We ran high‐resolution self‐similar and ΛCDM hydro‐simulations and built an analytical model to study this effect. Our model reproduces the ΛCDM simulation results to several per cent accuracy, passes various tests against self‐similar simulations, and shows a wider range of applicability than previous analytical models. Our model in its continuous version is free of simulation limitations, such as a finite simulation box and finite resolution, and allows an accurate prediction of the kinetic SZ power spectrum, Cl. For the Wilkinson Microwave Anisotropy Probe cosmology, we find l2Cl/(2π) ≃ 0.91 × 10−12[(1 +zreion)/10]0.34(l/5000) 0.23‐0.015(italicz reion−9) for the reionization redshift 6 < zreion < 20 and 3000 < l < 9000. The corresponding temperature fluctuation is several μK at these ranges. The dependence of Cl on the reionization history allows an accurate measurement of the reionization epoch. For the Atacama Cosmology Telescope (ACT) experiment, Cl can be measured with ∼1 per cent accuracy. Cl scales as (Ωbh)2σ4∼68. Given cosmological parameters, ACT would be able to constrain zreion with several per cent accuracy. Some multireionization scenarios degenerate in the primary CMB temperature and temperature–E polarization (TE) measurement can be distinguished with ∼ 10 σ confidence.

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Linear Gas Dynamics in the Expanding Universe

Abstract: We investigate the relationship between the dark matter and baryons in the linear regime. This relation is quantified by the so-called '' filtering scale.'' We show that a simple Gaussian Ansatz that uses the filtering scale provides a good approximation to the exact solution.

Cited by 28 publications

References 10 publications

The formation and gas content of high-redshift galaxies and minihaloes

The formation and gas content of high-redshift galaxies and minihaloes

The probability distribution function of the Lyman transmitted flux from a sample of Sloan Digital Sky Survey quasars

Precision era of the kinetic Sunyaev-Zel'dovich effect: simulations, analytical models and observations and the power to constrain reionization

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