On the absorption spectra of the quasars TOL 1037-271 and TOL 1038-272*

Cristiani, S.; Danziger, I. J.; Shaver, P. A.

doi:10.1093/mnras/227.3.639

Cited by 8 publications

(8 citation statements)

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“…Sargent ( 1987) reports high column density absorption systems at identical redshifts in the QSO pair Q2343 + 1229 and Q2343 + 1225 separated by 5.7 arcmin. Robertson (1987), Cristiani et al (1987), Sargent & Steidel (1987), and Jakobsen & Perryman (1992) discuss the QSO pair Tololo 1037-27/1038-27, separated by 18 arcmin, in which possible metal-line absorption system wavelength coincidences are seen. Uson et al detected 21 cm absorption and emission at redshift 3.4 separated by 33 arcmin.…”

Section: Discussionmentioning

confidence: 99%

Superclustering of damped Lyman-alpha absorption systems at redshifts above two

Francis¹,

Hewett²

1993

The Astronomical Journal

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Observations of two high redshift quasi-stellar objects (QSOs) (z=3.23 and z=3.18) separated by 8 arcmin on the sky are presented. Two strong Lyman-a absorption systems are seen in each QSO, and in both QSOs y one absorber is at a redshift of 2.380 and the other is at a redshift of 2.853. The velocities of the absorption systems differ between the lines of sight by only-300 kms-1 in both cases. To cover both lines of sight, the absorbers would need a transverse comoving size of-Mpc (for #0=0.5). The neutral hydrogen column densities inferred from the profiles lie between 1.2X10 18 and 1.2 XlO 20 cm-2 , and low ionization metal lines are associated with at least one of the absorption systems. The a posteriori joint probability of seeing these redshift coincidences is very low,-3x 10-4. If the absorbers are clustered, the probability of seeing the wavelength matches is enhanced, but a 20 Mpc scale supercluster with an absorber overdensity of-30 is required to give even a 5% probability of seeing the observed wavelength matches. If, alternatively, individual giant gas clouds cover both lines of sight, they must have masses in excess of 10 11 ^q. Any evidence for-5 Mpc structure at these redshifts poses challenge to bottom-up structure formation scenarios such as the standard Cold Dark Matter model.

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Section: Discussionmentioning

confidence: 99%

Superclustering of damped Lyman-alpha absorption systems at redshifts above two

Francis¹,

Hewett²

1993

The Astronomical Journal

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“…Whether the gas is associated with the QSO or with an intervening absorption complex is unclear however (see Jakobsen et al 1986;Ulrich & Perryman 1986;Cristiani et al 1987;Robertson 1987;Sargent & Steidel 1987;Dinshaw & Impey 1996;Lespine & Petitjean 1997). Absorption profiles of highionization lines are shown in Fig.…”

Section: Z Abs = 2 082mentioning

confidence: 99%

“…However the nature and origin of these common absorption systems are still unclear. There are arguments as well as counter arguments for (i) the absorption being produced by a super−cluster sitting in front of the two quasars and (ii) part of the systems being intrinsically associated with the QSOs (see Jakobsen et al 1986;Ulrich & Perryman 1986;Cristiani et al 1987;Robertson 1987;Sargent & Steidel 1987;Dinshaw & Impey 1996;Lespine & Petitjean 1997).…”

Section: Introductionmentioning

confidence: 99%

A near-solar metallicity damped Lyman-αsystem toward the BAL quasar Tol 1037-2703

Srianand

Petitjean

2001

A&A

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Abstract.We report the detection of a Broad Absorption Line (BAL) outflow in the spectrum of the zem (Mg ii) = 2.201 QSO Tol 1037−2703 with three main BALs at 36 000, 25 300 and 22 300 km s −1 outflow velocities. Although the overall flow is dominated by high ionization lines like N v and C iv, the gas of highest velocity shows absorption from Mg i, Mg ii and Fe ii. Covering factor arguments suggest that the absorbing complexes are physically associated with the QSO and have transverse dimensions smaller than that of the UV continuum emitting region (r < 0.1 pc). We show that the C iv absorption at z abs = 2.082 has a covering factor fc ∼ 0.86 and the absorption profile has varied over the last four years. The detection of absorption from excited fine structure levels of C ii and Si ii in narrow components embedded in the C iv trough reveals large density inhomogeneities. IR pumping is the most likely excitation process. The z abs = 2.139 system is a moderately damped Lyman-α system with log N(H i) ∼ 19.7. The weakness of the metal lines together with the high quality of the data make the metallicity measurements particularly reliable. The absolute metallicity is close to solar with −0.27, −0.49, −0.30). Lines from C i are detected but H2 is absent with a molecular to neutral hydrogen fraction less than 8×10 −6 . From the ionization state of the gas, we argue that the system is situated ∼few Mpc away from the QSO. High metallicity and low nitrogen abundance, [N/Zn] = −1.40, favor the idea that metals have been released by massive stars during a starburst of less than 0.5 Gyr of age. Using the upper limit on the C i * column density in two components, we obtain upper limits on the background temperature of 16.2 and 13.2 K respectively.

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“…(Or it may be interesting for obtaining very dense, random samples, as suggested for the Ly α forest in §4.2, or for studying certain pre-selected anomalies e.g. in the region around a close damper Ly α absorber pair: Francis et al 1996, and the ≈ 100 Mpc absorber cluster in the Tololo QSO sample near 1037-27: , Jakobsen et al 1986, Jakobsen, Perryman & Cristiani 1988, Robertson 1987, Cristiani, Danziger & Shaver 1987, Sargent & Steidel 1987, Jakobsen & Perryman 1992, Dinshaw & Impey 1996 We are in the process of acquiring more such QSO pair data to study the clustering properties of C IV absorbers on Mpc scales. samples.…”

Section: Metal-line Absorber Clusteringmentioning

confidence: 99%

Reobservation of Close QSO Groups: The Size Evolution and Shape of Lyα Forest Absorbers

Crotts

Fang

1998

ApJ

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In order to study the size and shape of the absorbers that lie in front of the QSOs, in particular the Ly α forest, we present an analysis of 785 absorption lines in the spectra of five QSOs in close groupings: a pair (LB9605: 1517+2357 at z = 1.834 and LB9612: 1517+2356 at z = 1.903, with a separation of 102 arcsec between them) and a triplet (KP 76: 1623+2651A at z = 2.467, KP 77:1623+2653 at z = 2.526, and KP 78: 1623+2651B at z = 2.605, with separations of 127, 147 and 177 arcsec between pairs 76:78, 76:77 and 77:78, respectively).Both of these QSO groups have been observed before, but these data represent a drastic increase in signal-to-noise ratio and/or wavelength coverage over earlier data, and provide a qualitatively different view of the nature of the absorbers.The pair samples a scale critical in determining the size upper bound of Ly α absorbers, with significant leverage in redshift compared to previous studies.In the case of the triplet, this represents the spatially densest sample of Ly α forest absorbers ever studied, and an almost ideally-suited probe of the shape of absorbers. We observe a significant number of Ly α lines in common between the triplet sightlines, for lines stronger than rest equivalent width W o > 0.4Å (and no detected metal lines) and velocity differences up to 200 km s −1 , corresponding to a two-point correlation function ξ = 1.88 +0.78 −0.50 on scales 0.5 to 0.8 h −1 Mpc with z = 2.14, and inconsistent at the 99.999% level with the absence of any clustering. These data also show that a significant fraction of the W o > 0.4Å Ly α forest absorbers span all three sightlines to the KP triplet, indicating that the strong-lined absorbers are consistent with nearly round shapes, chosen from a range of possible cylinders of different elongations. This may be inconsistent with results from hydrodynamic/gravitational simulations of H I in the early Universe indicating that the theoretical counterparts of Ly α forest clouds are AnalysisContinua were calculated and lines detected, de-blended and assigned identifications according to Crotts (1989). Deblending was performed using multiple gaussian fits instead of Voigt profiles in nearly all cases, with the exception of resolved lines. We use a lower than usual S/N cutoff of 3.5σ for line detections. We are confident of this approach because we are able to check our results for KP 77 against a high S/N Keck HIRES spectrum of the object, the highest S/N part of a larger sample collected for the triplet (Crotts, Burles & Tytler 1997). At a 3.5σ cutoff for the KPNO data, no false detections are found over the 3900-5700Å overlap between the two data sets. In fact the KPNO 4m observations do a good job of detecting all obvious lines in the Keck spectrum (except for some very weak lines in the red KPNO 4m spectrum past 4700Å), while, of course, not resolving very close lines. We are fairly confident of our linelists, therefore, and expect approximately four lines out of our 785 to be false detections due to statistical fluctuations. Absorption ...

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On the absorption spectra of the quasars TOL 1037-271 and TOL 1038-272*

Cited by 8 publications

References 0 publications

Superclustering of damped Lyman-alpha absorption systems at redshifts above two

Superclustering of damped Lyman-alpha absorption systems at redshifts above two

A near-solar metallicity damped Lyman-αsystem toward the BAL quasar Tol 1037-2703

Reobservation of Close QSO Groups: The Size Evolution and Shape of Lyα Forest Absorbers

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