Observations of Lyα Absorption in a Triple Quasar System

Young, Patrick; Impey, C. D.; Foltz, C. B.

doi:10.1086/319054

Cited by 27 publications

(48 citation statements)

References 28 publications

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“…Lastly, we present 1996 observations with FOS G190H of Q0107À0232. When combined with the published 1997 data ( Young et al 2001), the result is a doubling of the exposure time on this third sight line. No other quasar group has UV spectroscopy of comparable quality.…”

Section: Observationsmentioning

confidence: 77%

Lyα Absorption in the Quasar Triplet Q0107-025A, Q0107-025B, and Q0107-0232: Data Calibration and Line Selection

et al. 2006

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We present spectroscopic observations for quasars Q0107À025A, Q0107À025B, and Q0107À0232. For the first time, all data obtained with the Hubble Space Telescope's GHRS and FOS for these three quasars are combined. Ly absorbers selected from the spectra can be used to trace the coherence of the intergalactic medium ( IGM ) on scales of 1-2 h À1 70 Mpc over the redshift range 0:4 < z a < 0:9. A new analysis of double and triple absorber coincidences derived from the improved spectra is performed. Automated line-selection algorithms were used to detect absorption lines in the QSO spectra; coincident absorbers were identified across two and three sight lines based on their proximity to each other in velocity space. A control simulation designed to generate artificial absorption-line spectra was used to gauge the significance of the coincidences. Four intervening metal-line absorption systems are detected, with three of the four coincident to the A and B sight lines and one coincident across all three sight lines. This is evidence for substantial clustering among the objects responsible for the metalenriched gas. By contrast, large-scale coherence of the IGM gas is detectable but weak. Fewer than half of the absorbers are coincident on scales of 1-2 h À1 70 Mpc, a result that is significant at the 99% confidence level, and coherence arises preferentially in the higher column density gas. Triple absorber coincidences occur at a level that is significant at the 99% confidence level, which indicates that the higher column density gas has a planar geometry.

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Section: Observationsmentioning

confidence: 77%

Lyα Absorption in the Quasar Triplet Q0107-025A, Q0107-025B, and Q0107-0232: Data Calibration and Line Selection

et al. 2006

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“…The quasar pair LBQS 1343+264 A/B shows characteristic r 0 $ 300 h À1 70 at z $ 2 ( Bechtold et al 1994;Dinshaw et al 1994). At lower redshift, Young et al (2001) find a coherence length between Ly absorbers of 500-1000 kpc at 0:4 < z < 0:9 in a rare triple QSO system.…”

Section: Multiphase Igm Modelsmentioning

confidence: 82%

The Low‐zIntergalactic Medium. II. Lyβ, Ovi, and CiiiForest

Danforth

Shull

Rosenberg

et al. 2006

ApJ

134

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We present the results of a large survey of H i, O vi, and C iii absorption lines in the low-redshift (z < 0:3) intergalactic medium (IGM). We begin with 171 strong Ly absorption lines (W k ! 80 m8) in 31 AGN sight lines studied with the Hubble Space Telescope and measure corresponding absorption from higher order Lyman lines with FUSE. Higher order Lyman lines are used to determine N H i and b H i accurately through a curve-of-growth (COG) analysis. We find that the number of H i absorbers per column density bin is a power-law distribution,, with H i ¼ 1:68 AE 0:11. We made 40 detections of O vi kk1032, 1038 and 30 detections of C iii k977 out of 129 and 148 potential absorbers, respectively. The column density distribution of C iii absorbers has C iii ¼ 1:68 AE 0:04, similar to H i but not as steep as O vi ¼ 2:2 AE 0:1. From the absorption-line frequency, dN C iii /dz ¼ 12 þ3 À2 for W k (C iii) > 30 m8, we calculate a typical IGM absorber size r 0 $ 400 kpc, similar to scales derived by other means. The COGderived b-values show that H i samples material with T < 10 5 K, incompatible with a hot IGM phase. By calculating a grid of CLOUDY models of IGM absorbers with a range of collisional and photoionization parameters, we find it difficult to simultaneously account for the O vi and C iii observations with a single phase. Instead, the observations require a multiphase IGM in which H i and C iii arise in photoionized regions, while O vi is produced primarily through shocks. From the multiphase ratio N H i /N C iii , we infer the IGM metallicity to be Z C ¼ 0:12 Z , similar to our previous estimate of Z O ¼ 0:09 Z from O vi.

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“… References: (1) Smette et al (1992); (2) MTL98; (3) Smette et al (1995); (4) Foltz et al (1984); (5) Charlton, Churchill & Linder (1995); (6) Lopez, Hagen & Reimers (2000); (7) Bechtold et al (1994); (8) Fang et al (1996); (9) Dinshaw et al (1994); (10) Petitjean et al (1998); (11) Monier, Turnshek & Hazard (1999); (12) D'Odorico et al (1998); (13) Dinshaw et al (1995); (14) Dinshaw et al (1997); (15) Young, Impey & Foltz (2001); (16) Dinshaw et al (1998); (17) Aracil et al (2002). …”

Section: Absorber Size As a Function Of Nh Iunclassified

On the sizes of neutral hydrogen regions giving rise to damped Lyα absorption systems

Monier

Turnshek

Rao

2009

Monthly Notices of the Royal Astronomical Society

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Using quasi‐stellar object (QSO) absorption‐line spectra obtained along closely spaced sightlines, we examine the transverse sizes of regions containing large columns of neutral hydrogen gas at redshifts z≈ 1.5. The observations are primarily of intervening damped Lyα (DLA) and sub‐DLA absorption‐line systems in gravitationally lensed QSOs. In particular, Hubble Space Telescope spectroscopy of the four‐component Cloverleaf QSO (H1413+1143) reveals three new DLA/sub‐DLA systems at z≈ 1.44, 1.49 and 1.66. A neutral hydrogen column density of NH i≥ 2 × 1020 atoms cm−2 is required for a system to be classified as a DLA, but none of the three systems has an H i column density above the DLA threshold in all four components. Over component separations <1.4 arcsec in the Cloverleaf, corresponding to transverse sizes of ≈5–12 h−170 kpc, the H i column densities typically change by factors of ≈2–40. Similar observations of other QSOs containing absorption systems in the DLA regime are summarized from the literature. In addition to establishing approximate sizes for DLA regions, the results have implications for their volume‐averaged H i gas number densities and neutral gas masses. By combining our results on DLA absorber sizes with published results on the sizes of lower column density QSO absorbers, which however arise in very ionized regions, we infer the useful relation that the typical transverse size of an absorber in the redshift interval z≈[1, 2] is Sabs≈ 11 h−170[NH i/1020]−1/4 kpc.

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Observations of Lyα Absorption in a Triple Quasar System

Cited by 27 publications

References 28 publications

Lyα Absorption in the Quasar Triplet Q0107-025A, Q0107-025B, and Q0107-0232: Data Calibration and Line Selection

Lyα Absorption in the Quasar Triplet Q0107-025A, Q0107-025B, and Q0107-0232: Data Calibration and Line Selection

The Low‐zIntergalactic Medium. II. Lyβ, Ovi, and CiiiForest

On the sizes of neutral hydrogen regions giving rise to damped Lyα absorption systems

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