The Gunn-Peterson effect and the H I column density distribution of Lyman alpha forest clouds at z = 4

Webb, John R.; Barcons, X.; Carswell, R. F.; Parnell, Harriet

doi:10.1093/mnras/255.2.319

Cited by 44 publications

(36 citation statements)

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“…Jenkins & Ostriker (1991) and Webb et al (1992), acknowledging this problem, attempted to model the pixel intensity distribution with continuum absorption and variable contributions from discrete lines. Their results show that τ GP can be produced both ways, by blending of weak lines below the detection threshold or by a constant pedestal of absorption.…”

Section: Lyman Alpha Clouds Confined By the Pressure Of An Intercloudmentioning

confidence: 99%

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

Rauch

1998

Annu. Rev. Astron. Astrophys.

459

325

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Observations of redshifted Lyman α (Lyα) forest absorption in the spectra of quasistellar objects (QSOs) provide a highly sensitive probe of the distribution of gaseous matter in the universe. Over the past two decades, optical spectroscopy with large ground-based telescopes, and more recently ultraviolet (UV) spectroscopy from space, have yielded a wealth of information on what appears to be a gaseous, photoionized intergalactic medium (IGM), partly enriched by the products of stellar nucleosynthesis, residing in coherent structures over many hundreds of kiloparsecs.Recent progress with cosmological hydro-simulations based on hierarchical structure formation models has led to important insights into the physical structures giving rise to the forest. If these ideas are correct, a truly inter-and protogalactic medium [at high redshift (z ∼ 3), the main repository of baryons] collapses under the influence of dark matter gravity into flattened or filamentary structures, which are seen in absorption against background QSOs. With decreasing redshift, galaxies forming in the denser regions may contribute an increasing part of the Lyα absorption cross section. Comparisons between large data samples from the new generation of telescopes and artificial Lyα forest spectra from cosmological simulations promise to become a useful cosmological tool.

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Section: Lyman Alpha Clouds Confined By the Pressure Of An Intercloudmentioning

confidence: 99%

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

Rauch

1998

Annu. Rev. Astron. Astrophys.

459

325

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“…The extent to which this eect is important depends on the shape of the ionizing spectrum and its evolution, neither of which are well quantied. The lack of a detectable Gunn-Peterson Lyman-absorption trough in the spectra high-redshift QSO's (Steidel & Sargent 1987;Webb et al 1992) suggests the IGM is highly ionized. The ionizing radiation eld estimated from the proximity eect (J 10 21 erg cm 2 s 1 Hz 1 ; Lu et al 1991) appears sucient t o prevent the gas from cooling in halos of velocity dispersion less than 35km s 1 until z 1.…”

Section: Coolingmentioning

confidence: 99%

Dwarf elliptical galaxies

Ferguson

Binggeli

1994

The Astron Astrophys Rev

327

360

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Dwarf elliptical (dE) galaxies, with blue absolute magnitudes typically fainter than M B = 16, are the most numerous type of galaxy in the nearby universe. Tremendous advances have been made over the past several years in delineating the properties of both Local Group satellite dE's and the large dE populations of nearby clusters. We review some of these advances, with particular attention to how w ell currently available data can constrain (a) models for the formation of dE's, (b) the physical and evolutionary connections between dierent t ypes of galaxies (nucleated and nonnucleated dE's, compact E's, irregulars, and blue compact dwarfs) that overlap in the same portion of the mass-spectrum of galaxies, (c) the contribution of dE's to the galaxy luminosity functions in clusters and the eld, (d) the star-forming histories of dE's and their possible contribution to faint galaxy counts, and (e) the clustering properties of dE's.In addressing these issues, we highlight the extent to which selection eects temper these constraints, and outline areas where new data would be particularly valuable.

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“…The idea is to view a Lya forest spectrum as a random stochastic process (Press et al 1993). Every point in the spectrum is a random variable, e ¹t , drawn from the transmission probability density function f l ðe ¹t Þ, also known as flux decrement distribution function (Kim et al 1997;Rauch et al 1997) or distribution of intensities (Jenkins & Ostriker 1991;Webb et al 1992). In principle, we have a different probability density function at each wavelength such that, for example, the moments of f l are functions of wavelength.…”

Section: T E C H N I Q U Ementioning

confidence: 99%

“…We can define an effective optical depth, t eff , as a function of observed wavelength, l, by e ¹t eff ðlÞ ϵ he ¹tðlÞ i: ð1Þ In the following we will neglect any contribution to t eff from the classical Gunn-Peterson effect which is limited to t GP Շ 0:04 (Webb et al 1992 …”

Section: The Mean Lya Transmissionmentioning

confidence: 99%

Large-scale structure in the Lyman- forest: a new technique

Liske

Webb

Carswell

1998

Monthly Notices of the Royal Astronomical Society

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A B S T R A C TWe present a new technique for detecting structure on Mpc scales in the Lya forest. The technique is easy to apply in practice since it does not involve absorption-line fitting, but rather is based on the statistics of the transmitted flux. It identifies and assesses the statistical significance of regions of overdense or underdense Lya absorption and is fairly insensitive to the quality of the data. Using extensive simulations, we demonstrate that the new method is significantly more sensitive to the detection of large-scale structure in the Lya forest than a traditional two-point correlation function analysis of fitted absorption lines.

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The Gunn-Peterson effect and the H I column density distribution of Lyman alpha forest clouds at z = 4

Cited by 44 publications

References 0 publications

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

The Lyman Alpha Forest in the Spectra of Quasistellar Objects

Dwarf elliptical galaxies

Large-scale structure in the Lyman- forest: a new technique

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