The ESO UVES Advanced Data Products Quasar Sample – IV. On the deficiency of argon in DLA systems

Zafar, T.; Vladilo, G.; Péroux, Céline; Molaro, P.; Centurión, M.; D’Odorico, V.; Abbas, Kumail; Popping, Attila

doi:10.1093/mnras/stu1904

Cited by 13 publications

(18 citation statements)

References 59 publications

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“…As AGN and quasars are key factors for galaxy evolution directly as essential ingredients in the galaxy formation recipe and indirectly as probes of intervening material, for example, of chemical evolution (Smith et al 1979;Pettini et al 1994;Lu et al 1996;Zafar et al 2014;Berg et al 2016;Krogager et al 2019), it is very important to get a complete census of AGN, in general, and of quasars in particular. The early work of Sandage (1965) already demonstrated that the original radio-selection of quasars only reveals a minority of the underlying population (the radio-loud quasars).…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2

Heintz

Fynbo

Geier

et al. 2020

A&A

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Here we explore the efficiency and fidelity of a purely astrometric selection of quasars as point sources with zero proper motions in the Gaia data release 2 (DR2). We have built a complete candidate sample including 104 Gaia-DR2 point sources, which are brighter than 20th magnitude in the Gaia G-band within one degree of the north Galactic pole (NGP); all of them have proper motions that are consistent with zero within 2σ uncertainty. In addition to pre-existing spectra, we have secured long-slit spectroscopy of all the remaining candidates and find that all 104 stationary point sources in the field can be classified as either quasars (63) or stars (41). One of the new quasars that we discover is particularly interesting as the line-of-sight to it passes through the disc of a foreground (z = 0.022) galaxy, which imprints both NaD absorption and dust extinction on the quasar spectrum. The selection efficiency of the zero-proper-motion criterion at high Galactic latitudes is thus ≈60%. Based on this complete quasar sample, we examine the basic properties of the underlying quasar population within the imposed limiting magnitude. We find that the surface density of quasars is 20 deg−2 (at G < 20 mag), the redshift distribution peaks at z ∼ 1.5, and only eight systems (13-3+5%) show significant dust reddening. We then explore the selection efficiency of commonly used optical, near-, and mid-infrared quasar identification techniques and find that they are all complete at the 85−90% level compared to the astrometric selection. Finally, we discuss how the astrometric selection can be improved to an efficiency of ≈70% by including an additional cut requiring parallaxes of the candidates to be consistent with zero within 2σ. The selection efficiency will further increase with the release of future, more sensitive astrometric measurements from the Gaia mission. This type of selection, which is purely based on the astrometry of the quasar candidates, is unbiased in terms of colours and intrinsic emission mechanisms of the quasars and thus provides the most complete census of the quasar population within the limiting magnitude of Gaia.

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Section: Introductionmentioning

confidence: 99%

Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2

Heintz

Fynbo

Geier

et al. 2020

A&A

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“…The physical nature of DLAs also influences their gas phase abundances, including the role of ionizing sources (D'Odorico 2007;Ellison et al 2010;Zafar et al 2014b) or the amount of dust (e.g. Pettini et al 1994;Kulkarni et al 1997;Akerman et al 2005;Krogager et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Chemical abundances of the damped Lyman α systems in the XQ-100 survey

Berg¹,

Ellison²,

Sánchez-Ramírez³

et al. 2016

Mon. Not. R. Astron. Soc.

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The XQ-100 survey has provided high signal-noise spectra of 100 redshift 3-4.5 quasars with the X-Shooter spectrograph. The metal abundances for 13 elements in the 41 damped Lyα systems (DLAs) identified in the XQ-100 sample are presented, and an investigation into abundances of a variety of DLA classes is conducted. The XQ-100 DLA sample contains five DLAs within 5000 km s −1 of their host quasar (proximate DLAs; PDLAs) as well as three sightlines which contain two DLAs within 10,000 km s −1 of each other along the same line-of-sight (multiple DLAs; MDLAs). Combined with previous observations in the literature, we demonstrate that PDLAs with logN(HI)< 21.0 show lower [S/H] and [Fe/H] (relative to intervening systems with similar redshift and N(Hi)), whilst higher [S/H] and [Si/H] are seen in PDLAs with logN(HI)> 21.0. These abundance discrepancies are independent of their line-of-sight velocity separation from the host quasar, and the velocity width of the metal lines (v 90 ). Contrary to previous studies, MDLAs show no difference in [α/Fe] relative to single DLAs matched in metallicity and redshift. In addition, we present follow-up UVES data of J0034+1639, a sightline containing three DLAs, including a metalpoor DLA with [Fe/H]= −2.82 (the third lowest [Fe/H] in DLAs identified to date) at z abs = 4.25. Lastly we study the dust-corrected [Zn/Fe], emphasizing that near-IR coverage of X-Shooter provides unprecedented access to Mgii, Caii and Tiii lines (at redshifts 3-4) to provide additional evidence for subsolar [Zn/Fe] ratio in DLAs.

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“…We have modelled these systems in detail using the spectral simulation code CLOUDY to understand the physical conditions in highredshift DLAs. The 3 DLAs for which we study the physical environment are the systems at: zabs = 2.3377 towards LBQS 1232+0815 (Srianand, Petitjean & Ledoux 2000;Varshalovich et al 2001;Ivanchik et al 2010;Balashev et al 2011;Zafar et al 2014), zabs = 2.41837 towards SDSS J143912.04+111740.5 (Noterdaeme et al 2008b;Srianand et al 2008), and zabs = 2.6265 towards FBQS J081240.6+320808 (Prochaska, Howk & Wolfe 2003;Jorgenson et al 2009;Tumlinson et al 2010;Jorgenson et al 2010). Typically, DLAs may constitute absorption arising from more than one cloud along the line-of-sight.…”

Section: Introductionmentioning

confidence: 99%

Physical conditions in three high-zH₂-bearing DLAs: implications for grain size

Shaw

Rawlins

Srianand

2016

Mon. Not. R. Astron. Soc.

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We present results of our numerical simulation of three H2-bearing damped Lyman α absorbers (DLAs) in the redshift interval ~ 2-3. The systems we have modelled are the DLAs at zabs = 2.3377 towards the quasar LBQS 1232+0815, at zabs = 2.41837 towards SDSS J143912.04+111740.5 and at zabs = 2.6265 towards FBQS J081240.6+320808. We have used the spectral synthesis code CLOUDY to simulate the physical environment of these DLAs, and constrain the density, radiation field, geometry and dust-grain properties of the DLAs selfconsistently based on the observed column densities of various atomic and molecular species such as H I, fine structure lines of C I and the rotational level population of H2. In our models, we explore the effect of grain size distribution on the predicted column densities of different species. Within the allowed uncertainties in the inferred dust-to-gas ratio, both models with standard ISM grains and smaller-sized grains reproduce the observations equally well. Improved constraints on dust-to-gas ratio and line-of-sight extinction are important for probing the grain size distribution in high-z DLAs. We find the H2-bearing clouds to have line-of-sight thickness in the range 1-6 pc, consistent with what has been found using partial coverage or 21-cm observations in some high-z DLAs.

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The ESO UVES Advanced Data Products Quasar Sample – IV. On the deficiency of argon in DLA systems

Cited by 13 publications

References 59 publications

Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2

Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2

Chemical abundances of the damped Lyman α systems in the XQ-100 survey

Physical conditions in three high-zH₂-bearing DLAs: implications for grain size

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The ESO UVES Advanced Data Products Quasar Sample – IV. On the deficiency of argon in DLA systems

Cited by 13 publications

References 59 publications

Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2

Spectroscopic classification of a complete sample of astrometrically-selected quasar candidates using Gaia DR2

Chemical abundances of the damped Lyman α systems in the XQ-100 survey

Physical conditions in three high-zH2-bearing DLAs: implications for grain size

Contact Info

Product

Resources

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Physical conditions in three high-zH₂-bearing DLAs: implications for grain size