Size estimates for intervening C IV absorbers from high-resolution spectroscopy of APM 0827+5255

Tzanavaris, P.; Carswell, R. F.

doi:10.1046/j.1365-8711.2003.06355.x

Cited by 9 publications

(9 citation statements)

References 42 publications

(66 reference statements)

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“…In either case, variations over short time scales are incompatible with absorption in large intergalactic clouds. A firm lower limit on the size of intergalactic HI-absorbing clouds is approximately a few kpc (Foltz et al 1984, McGill 1990, Bechtold & Yee 1995, Rauch 1998, which is similar to recent direct estimates of the sizes of intergalactic C IV-absorbing clouds (Tzanavaris et al 2003). Assuming the clouds are uniform and do not have sharp edges, the time scale for absorption line strength variations occurring via bulk motions will be roughly the time needed for this minimum cloud to cross our line of sight.…”

Section: Introductionsupporting

confidence: 79%

Variability Tests for Intrinsic Absorption Lines in Quasar Spectra

Narayanan

Hamann

Barlow

et al. 2004

ApJ

129

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Quasar spectra have a variety of absorption lines whose origins range from energetic winds expelled from the central engines to unrelated, intergalactic clouds. We present multi-epoch, medium resolution spectra of eight quasars at z~2 that have narrow ``associated'' absorption lines (AALs, within $\pm$5000 km s^{-1} of the emission redshift). Two of these quasars were also known previously to have high-velocity mini-broad absorption lines (mini-BALs). We use these data, spanning ~17 years in the observed frame with two to four observations per object, to search for line strength variations as an identifier of absorption that occurs physically near (``intrinsic'' to) the central AGN. Our main results are the following: Two out of the eight quasars with narrow AALs exhibit variable AAL strengths. Two out of two quasars with high-velocity mini-BALs exhibit variable mini-BAL strengths. We also marginally detect variability in a high-velocity narrow absorption line (NAL) system, blueshifted \~32,900 km s^{-1}$ with respect to the emission lines. No other absorption lines in these quasars appeared to vary. The outflow velocities of the variable AALs are 3140 km s^{-1} and 1490 km s^{-1}. The two mini-BALs identify much higher velocity outflows of ~28,400 km s^{-1} and ~52,000 km s^{-1}. Our temporal sampling yields upper limits on the variation time scales from 0.28 to 6.1 years in the quasar rest frames. The corresponding minimum electron densities in the variable absorbers, based on the recombination time scale, are \~40,000 cm^{-3} to ~1900 cm^{-3}. The maximum distances of the absorbers from the continuum source, assuming photoionization with no spectral shielding, range from ~1.8 kpc to ~7 kpc.Comment: 16 pages, 4 figures, ApJ, accepte

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Section: Introductionsupporting

confidence: 79%

Variability Tests for Intrinsic Absorption Lines in Quasar Spectra

Narayanan

Hamann

Barlow

et al. 2004

ApJ

129

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“…These b values are broad and smooth compared to the thermal widths for gas at the highest expected temperature near T = 10 5 K (Arnaud & Rothenflug 1985; Hamann et al 1995) for a photoionized gas near a quasar (33 km s −1 for H and less than 10 km s −1 for C and N). They are also broader than typical non‐damped Lyα intervening C iv , N v and O vi absorption lines, which have on average b < 12–14 km s −1 for O vi , and b < 10–12 km s −1 for C iv and N v (Tzanavaris & Carswell 2003; Bergeron & Herbert‐Fort 2005; Schaye et al 2007; Fox et al 2008). These profiles, therefore, exhibit morphologies consistent with formation in an outflow.…”

Section: Discussionmentioning

confidence: 98%

The origins of a rich absorption line complex in a quasar at redshift 3.45

Simon¹,

Hamann

2010

Monthly Notices of the Royal Astronomical Society

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We discuss the nature and origin of a rich complex of narrow absorption lines in the quasar J102325.31+514251.0 at redshift 3.447. We measure nine C IV(λλ1548, 1551) absorption line systems with velocities from −1400 to −6200 km s −1 , and full widths at half-minimum ranging from 16 to 350 km s −1 . We also detect other absorption lines in these systems, including H I, C III, N V, O VI and Si IV. Lower ionization lines are not present, indicating a generally high degree of ionization in all nine systems. The total hydrogen column densities range from 10 17.2 to 10 19.1 cm −2 . The tight grouping of these lines in the quasar spectrum suggests that most or all of the absorbing regions are physically related. We examine several diagnostics to estimate more directly the location and origin of each absorber. Four of the systems can be attributed to a quasar-driven outflow based on line profiles that are smooth and broad compared to thermal linewidths and to the typical absorption lines formed in intergalactic gas or galaxy haloes. Several systems also have other indicators of a quasar outflow origin, including partial covering of the quasar emission source (e.g. in systems with speeds too high for a starburstdriven flow), O VI column densities above 10 15 cm −2 and an apparent line-lock in C IV (in two of the narrow profile systems). A search for line variability yielded null results, although with very poor constraints because the comparison spectra have much lower resolution. Altogether (but not including the tentative line-lock) there is direct evidence for six of the nine systems forming in a quasar outflow. Consistent with a near-quasar origin, eight of the systems have metallicity values or lower limits in the range Z 1-8 Z . The lowest velocity system, which has an ambiguous location based on the diagnostics mentioned above, also has the lowest metallicity, Z 0.3 Z , and might form in a non-outflow environment farther from the quasar. Overall, however, this complex of narrow absorption lines can be identified with a highly structured, multicomponent outflow from the quasar. The high metallicities are similar to those derived for other quasars at similar redshifts and luminosities, and are consistent with evolution scenarios wherein quasars appear after the main episodes of star formation and metal enrichment in the host galaxies.

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“…Tzanavaris & Carswell (2003) used evidence for partial coverage of z ≈ 3 C iv components in the spectrum of one quasar to infer a lower limit on the size of 11 150 pc and a most likely size R ∼ 1 kpc. The study of Rauch, Sargent & Barlow (2001), who analysed C iv coincidences in three gravitationally lensed quasar pairs at z ∼ 2–3, is most relevant for us.…”

Section: Discussionmentioning

confidence: 99%

A large population of metal-rich, compact, intergalactic C IV absorbers - evidence for poor small-scale metal mixing

Schaye

Carswell

Kim

2007

Monthly Notices of the Royal Astronomical Society

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146

182

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We carried out a survey for high‐metallicity C iv absorbers at redshift z≈ 2.3 in nine high‐quality quasar spectra. Using a novel analysis technique, based on detections of C iv lines and automatically determined upper limits on the column densities of H i, C iii, N v and O vi, we find a large population of photoionized, compact (R∼ 102 pc), metal‐rich (Z≳ Z⊙) C iv clouds with moderate densities (nH∼ 10−3.5 cm−3), properties that we show are robust with respect to uncertainties in the ionization model. In particular, local sources of ionizing radiation, overabundance of oxygen, departures from ionization equilibrium and collisional ionization would all imply more compact clouds. The clouds are too small to be self‐gravitating and pressure confinement is only consistent under special conditions. We argue that the clouds are, in any case, likely to be short‐lived and we demonstrate that this implies that the clouds could easily have been responsible for the transport of all metals that end up in the intergalactic medium (IGM). When metal‐rich clouds reach pressure equilibrium with the general, photoionized IGM, the heavy elements will still be concentrated in small high‐metallicity patches, but they will look like ordinary, low‐metallicity absorbers. We conclude that intergalactic metals are poorly mixed on small scales and that nearly all of the IGM, and thus the universe, may therefore be of primordial composition.

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Size estimates for intervening C IV absorbers from high-resolution spectroscopy of APM 0827+5255

Cited by 9 publications

References 42 publications

Variability Tests for Intrinsic Absorption Lines in Quasar Spectra

Variability Tests for Intrinsic Absorption Lines in Quasar Spectra

The origins of a rich absorption line complex in a quasar at redshift 3.45

A large population of metal-rich, compact, intergalactic C IV absorbers - evidence for poor small-scale metal mixing

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