Elemental Abundances in Quasistellar Objects: Star Formation and Galactic Nuclear Evolution at High Redshifts

Hamann, Fred; Ferland, Gary J.

doi:10.1146/annurev.astro.37.1.487

Cited by 384 publications

(396 citation statements)

References 255 publications

(238 reference statements)

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“…The ionization parameter U is constrained by the simultaneous presence of Mg  and N  in the narrow component A1, which requires −2.8 < ∼ log U < ∼ −2.5 for ionization fractions >1% for both ions, according to the calculations of Hamann & Ferland (1999). We adopt log U = −2.8 for ease of comparison with Hamann et al (2001).…”

Section: Absorption From Excited Levels: Electron Density and Distancmentioning

confidence: 99%

VLT + UVES spectroscopy of the low-ionization intrinsic absorber in SDSS J001130.56+005550.7

Hutsemékers

Brinkmann²

2004

A&A

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Abstract. We analyse high-resolution VLT+UVES spectra of the low-ionization intrinsic absorber observed in the BAL QSO SDSS J001130.56+005550.7. Two narrow absorption systems at velocities −600 km s −1 and −22 000 km s −1 are detected. The low-velocity system is part of the broad absorption line (BAL), while the high-velocity one is well detached. While most narrow absorption components are only detected in the high-ionization species, the lowest velocity component is detected in both highand low-ionization species, including in the excited Si  and C  lines. From the analysis of doublet lines, we find that the narrow absorption lines at the low-velocity end of the BAL trough are completely saturated but do not reach zero flux, their profiles being dominated by a velocity-dependent covering factor. The covering factor is significantly smaller for Mg  than for Si  and N , which demonstrates the intrinsic nature of absorber. From the analysis of the excited Si  and C  lines in the lowest velocity component, we find an electron density 10 3 cm −3 . Assuming photoionization equilibrium, we derive a distance 20 kpc between the low-ionization region and the quasar core. The correspondence in velocity of the high-and low-ionization features suggests that all these species must be closely associated, hence formed at the same distance of ∼20 kpc, much higher than the distance usually assumed for BAL absorbers.

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Section: Absorption From Excited Levels: Electron Density and Distancmentioning

confidence: 99%

VLT + UVES spectroscopy of the low-ionization intrinsic absorber in SDSS J001130.56+005550.7

Hutsemékers

Brinkmann²

2004

A&A

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“…The observed flux ratio of N V/C IV is 0.46 in 3C 273 (Baldwin et al 1989), which gives a metal abundance A = Z/Z ⊙ ≈ 10 from Fig. 6 of Hamann & Ferland (1999). The superluminal motion has been extensively studied, the latest observation shows that the apparent velocities for different components are from 9c to 22c (Jorstad et al 2001).…”

Section: A Predicted Blue-shifted Kα Line In 3c 273mentioning

confidence: 90%

“…We findṁ ≈ 0.4, about half the Eddington luminosity, similar to Courvoisier (1998). The metallicity can be estimated through the flux ratio of N V/C IV (Hamann & Ferland 1999). The observed flux ratio of N V/C IV is 0.46 in 3C 273 (Baldwin et al 1989), which gives a metal abundance A = Z/Z ⊙ ≈ 10 from Fig.…”

Section: A Predicted Blue-shifted Kα Line In 3c 273mentioning

confidence: 96%

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A Possible Feature of the Thermal Matter in Relativistic Jets in Radio-Loud Quasars

Wang

Staubert

Courvoisier³

2005

Growing Black Holes: Accretion in a Cosmological Context

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Abstract. It has been suggested that relativistic jets in quasars may contain a considerable amount of thermal matter. In this paper, we explore the possibility that the Kα line from the thermal matter may appear at tens of keV due to a high Doppler blue-shift. In the jet comoving frame, the energy density of photons originally emitted by the accretion disk and reflected off the broad line region clouds dominates over that of photons of other origin. We discuss the photoionization states of the thermal matter and find that the irons elements are neutral. The high metallicity in quasars enhances the possibility to detect the thermal matter in the relativistic jet in some radio-loud quasars. A highly Doppler blue-shifted Kα line may be detected. We make a prediction for 3C 273, in which the Kα line luminosity might be of the order 3.0 × 10 44 erg s −1 with an equivalent width of 2.4 keV. Such a line could be detected in a future mission.

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“…As is commonly known from nucleosynthesis calculations, type II supernovae (SNe II) from massive stars mainly supply α-elements, while type Ia supernovae (SNe Ia) from binary systems mainly supply iron [1,2]. Since the lifetime of SN Ia is estimated to be typically t Ia ∼ 1 Gyr [3,4] which is 1-2 orders longer than that of SN II, the iron enrichment should be delayed behind α, causing a break in [α/Fe] at the elapsed time t ∼ t Ia from the formation of the first stars [5][6][7][8]. Such a break, although confirmed from observations of long-lived metal-poor stars in the solar neighborhood, still requires confirmation at high redshift corresponding to t ∼ t Ia in the early Universe.…”

Section: Introductionmentioning

confidence: 99%

Chemical Evolution of the Universe at 0.7 < z < 1.6 Derived from Abundance Diagnostics of Quasars

Sameshima¹,

Yoshii²,

Kawara³

2017

Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016)

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We present an analysis of Mg II λ2798 and Fe II UV emission lines for archival Sloan Digital Sky Survey (SDSS) quasars to explore diagnostics of the Mg/Fe abundance ratio in a broad-line region cloud. Our sample consists of 17,432 quasars selected from the SDSS Data Release 7 with a redshift range of 0.72 < z < 1.63. An anticorrelation between Mg II equivalent width (EW) and the Eddington ratio is found, while only a weak positive correlation is found between Fe II EW and the Eddington ratio. To investigate the origin of these differing behaviors of Mg II and Fe II emission lines, we have performed photoionization calculations using the Cloudy code. We find that their EW correlations with the Eddington ratio can be explained by just changing the cloud gas density; this indicates that the Mg II/Fe II flux ratio, which has been used as a first-order proxy for the Mg/Fe abundance ratio in chemical evolution studies with quasar emission lines, depends largely on the cloud gas density. By correcting this density dependence, we propose new diagnostics of the Mg/Fe abundance ratio for a broad-line region cloud. Using this new method, we have succeeded for the first time in measuring the evolution of the Mg/Fe abundance ratio as a function of redshift. From comparison with chemical evolution models, we suggest that α-enrichment by mass loss from metal-poor intermediate-mass stars occurred at z ∼ 2 or earlier.

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Elemental Abundances in Quasistellar Objects: Star Formation and Galactic Nuclear Evolution at High Redshifts

Cited by 384 publications

References 255 publications

VLT + UVES spectroscopy of the low-ionization intrinsic absorber in SDSS J001130.56+005550.7

VLT + UVES spectroscopy of the low-ionization intrinsic absorber in SDSS J001130.56+005550.7

A Possible Feature of the Thermal Matter in Relativistic Jets in Radio-Loud Quasars

Chemical Evolution of the Universe at 0.7 < z < 1.6 Derived from Abundance Diagnostics of Quasars

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