The gaseous extent of galaxies and the origin of Lyman-alpha absorption systems: A survey of galaxies in the fields of Hubble Space Telescope spectroscopic target QSOs

Lanzetta, Kenneth M.; Bowen, D.; Tytler, David; Webb, John R.

doi:10.1086/175459

Cited by 286 publications

(348 citation statements)

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“…H 0 \ 100 PEEBLES Vol. 557 limit or Mg II quasar absorption-line systems also tend to be quite close to galaxies (Bergeron & Boisse 1991 ;Steidel, Dickinson, & Persson 1994 ;Lanzetta et al 1995). This is observed at redshifts where the galaxy distribution is not densely mapped, but I expect such gas clouds are similarly close to galaxies at z D 0.…”

Section: Elsassermentioning

confidence: 86%

The Void Phenomenon

Peebles

2001

ApJ

320

362

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Advances in theoretical ideas on how galaxies formed have not been strongly inÑuenced by the advances in observations of what might be in the voids between the concentrations of ordinary optically selected galaxies. The theory and observations are maturing, and the search for a reconciliation o †ers a promising opportunity to improve our understanding of cosmic evolution. I comment on the development of this situation and present an update of a nearest neighbor measure of the void phenomenon that may be of use in evaluating theories of galaxy formation.

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Section: Elsassermentioning

confidence: 86%

The Void Phenomenon

Peebles

2001

ApJ

320

362

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“…The allowed large velocity interval is guided by previous observations (e.g. Lanzetta et al 1995) which show a velocity dispersion of ∼ 190 km s −1 between galaxies and their associated Lyα absorbers. For each detected Lyα absorber, we further examine whether associated ionic transitions, such as C IV, C II, Si IV, S III, and Si II, are also present in the spectral range covered by the STIS/COS data.…”

Section: Absorption Constraints Of Circumgalactic Baryonsmentioning

confidence: 87%

“…In principle, this circumgalactic gas provides the fuel necessary for sustaining star formation in galaxies, while at the same time it is also being replenished with both newly accreted (and presumably chemically pristine) intergalactic gas and chemically enriched materials ei-hydrogen Lyα λ 1215 (e.g. Lanzetta et al 1995;Chen et al 1998Chen et al , 2001aTripp et al 1998;Wakker & Savage 2009;Steidel et al 2010;Prochaska et al 2011;Thom et al 2012;Stocke et al 2013;Rudie et al 2013), the C IV λλ 1548, 1550 doublet (e.g. Chen et al 2001b;Adelberger et al 2005;Steidel et al 2010), the Mg II λλ 2796, 2803 doublet (e.g.…”

Section: Introductionmentioning

confidence: 99%

Mining circumgalactic baryons in the low-redshift universe

Liang

Chen

2014

Monthly Notices of the Royal Astronomical Society

143

229

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This paper presents an absorption-line study of the multiphase circumgalactic medium (CGM) based on observations of Lyα, C II, C IV, Si II, Si III, and Si IV absorption transitions in the vicinities of 195 galaxies at redshift z < 0.176. The galaxy sample is established based on a cross-comparison between public galaxy and QSO survey data and is characterized by a median redshift of z = 0.041, a median projected distance of d = 362 kpc to the sightline of the background QSO, and a median stellar mass of log (M star /M ) = 9.7 ± 1.1. Comparing the absorber features identified in the QSO spectra with known galaxy properties has led to strong constraints for the CGM absorption properties at z < ∼ 0.176. First, abundant hydrogen gas is observed out to d ∼ 500 kpc, well beyond the dark matter halo radius R h of individual galaxies, with a mean covering fraction of ≈ 60%. In contrast, no heavy elements are detected at d > ∼ 0.7 R h from either low-mass dwarfs or high-mass galaxies. The lack of detected heavy elements in low-and high-ionization states suggests that either there exists a chemical enrichment edge at d ≈ 0.7 R h or gaseous clumps giving rise to the observed absorption lines cannot survive at these large distances. Considering all galaxies at d > R h leads to a strict upper limit for the covering fraction of heavy elements of ≈ 3% (at a 95% confidence level) over d = (1 − 9) R h . At d < R h , differential covering fraction between low-and high-ionization gas is observed, suggesting that the CGM becomes progressively more ionized from d < 0.3 R h to larger distances. Comparing CGM absorption observations at low and high redshifts shows that at a fixed-fraction of R h the CGM exhibits stronger mean absorption at z = 2.2 than at z ∼ 0 and that the distinction is most pronounced in low-ionization species traced by C II and Si II absorption lines. We discuss possible pseudo-evolution of the CGM as a result of misrepresentation of halo radius, and present a brief discussion on the implications of these findings.

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“…On the other hand, isolated HI clouds with masses and sizes comparable to present dwarf galaxies would be easily seen with modern radio telescopes hence they must be very rare. This conclusion is reinforced by the damped QSO absorption lines that tend to occur in the haloes of bright galaxies and not in smaller HI clouds (Lanzetta et al 1995; however see discussion in Sect. 8.2).…”

Section: Hi Cloudsmentioning

confidence: 95%

The most metal-poor galaxies

Kunth

Östlin

2000

Astronomy and Astrophysics Review

381

428

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Metallicity is a key parameter that controls many aspects in the formation and evolution of stars and galaxies. In this review we focus on the metal deficient galaxies, in particular the most metal-poor ones, because they play a crucial rôle in the cosmic scenery. We first set the stage by discussing the difficult problem of defining a global metallicity and how this quantity can be measured for a given galaxy. The mechanisms that control the metallicity in a galaxy are reviewed in detail and involve many aspects of modern astrophysics: galaxy formation and evolution, massive star formation, stellar winds, chemical yields, outflows and inflows etc. Because metallicity roughly scales as the galactic mass, it is among the dwarfs that the most metalpoor galaxies are found. The core of our paper reviews the considerable progress made in our understanding of the properties and the physical processes that are at work in these objects. The question on how they are related and may evolve from one class of objects to another is discussed. While discussing metal-poor galaxies in general, we present a more detailed discussion of a few very metal-poor blue compact dwarf galaxies like IZw18. Although most of what is known relates to our local universe, we show that it pertains to our quest for primeval galaxies and is connected to the question of the origin of structure in the universe. We discuss what QSO absorption lines and known distant galaxies tell us already? We illustrate the importance of star-forming metal-poor galaxies for the determination of the primordial helium abundance, their use as distance indicator and discuss the possibility to detect nearly metal-free galaxies at high redshift from Lyα emission.

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The gaseous extent of galaxies and the origin of Lyman-alpha absorption systems: A survey of galaxies in the fields of Hubble Space Telescope spectroscopic target QSOs

Cited by 286 publications

References 0 publications

The Void Phenomenon

The Void Phenomenon

Mining circumgalactic baryons in the low-redshift universe

The most metal-poor galaxies

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