Far-ultraviolet absorption spectra of quasars: How to find missing hot gas and metals

Verner, D. A.; Tytler, David; Barthel, Pieter

doi:10.1086/174392

Cited by 108 publications

(148 citation statements)

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“…For J = 3/2, the present value, 0.1064, lies just inside the experimental range 0.123 ± 0.017 (Bengtsson et al 1992), and is in reasonable agreement with the experimental values 0.14 (Andersen et al 1974) and 0.139 (Lotrian et al 1980). The present value is in good agreement with the theoretical values 0.11 (Holmgren 1975) and 0.113 (Verner et al 1994). For J = 5/2, the present value, 0.1596, is in reasonable agreement with the experimental values 0.21 (Andersen et al 1974) and 0.214 (Lotrian et al 1980), and is in excellent agreement with the theoretical values 0.16 (Holmgren 1975) and 0.161 (Verner et al 1994).…”

Section: Results For As Isupporting

confidence: 91%

“…The present value is in good agreement with the theoretical values 0.11 (Holmgren 1975) and 0.113 (Verner et al 1994). For J = 5/2, the present value, 0.1596, is in reasonable agreement with the experimental values 0.21 (Andersen et al 1974) and 0.214 (Lotrian et al 1980), and is in excellent agreement with the theoretical values 0.16 (Holmgren 1975) and 0.161 (Verner et al 1994). …”

Section: Results For As Isupporting

confidence: 91%

“…Calculations have been performed using a variety of techniques. The present value, 0.0532, is in good agreement with the theoretical value 0.0584 (Verner et al 1994) and lies between the theoretical values 0.03 (Lawrence 1967) and 0.06 (Holmgren 1975). For J = 3/2, the present value, 0.1064, lies just inside the experimental range 0.123 ± 0.017 (Bengtsson et al 1992), and is in reasonable agreement with the experimental values 0.14 (Andersen et al 1974) and 0.139 (Lotrian et al 1980).…”

Section: Results For As Isupporting

confidence: 90%

“…c Lotrian et al (1980): uses emission spectroscopy. d Verner et al (1994): gives a critical review of f -values from previous compilations. e Holmgren (1975): uses optimized Hartree-Fock-Slater local exchange approximation and relativistic wave functions.…”

Section: Methods Of Calculationmentioning

confidence: 99%

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Oscillator strengths for AsI-III

Ganas

2000

Astron. Astrophys. Suppl. Ser.

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Section: Results For As Isupporting

confidence: 91%

Section: Results For As Isupporting

confidence: 91%

Section: Results For As Isupporting

confidence: 90%

Section: Methods Of Calculationmentioning

confidence: 99%

See 2 more Smart Citations

Oscillator strengths for AsI-III

Ganas

2000

Astron. Astrophys. Suppl. Ser.

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“…[19]. The continuous oscillator strength, df /dǫ, was found using Verner's [20] analytic fits for partial photoionization cross sections.…”

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confidence: 99%

Collisional properties of trapped cold chromium atoms

Pavlović

Roos²,

Côté

et al. 2004

Phys. Rev. A

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We report on calculations of the elastic cross section and thermalization rate for collision between two maximally spin-polarized chromium atoms in the cold and ultracold regimes, relevant to buffergas and magneto-optical cooling of chromium atoms. We calculate ab initio potential energy curves for Cr2 and the van der Waals coefficient C6, and construct interaction potentials between two colliding Cr atoms. We explore the effect of shape resonances on elastic cross section, and find that they dramatically affect the thermalization rate. Our calculated value for the s-wave scattering length is compared in magnitude with a recent measurement at ultracold temperatures.Collisions of atoms at ultracold temperatures have received considerable attention because of their importance in cooling and trapping of atoms [1] and their role in high precision spectroscopy [2] and Bose-Einstein condensation [3]. Processes occurring in the cold regime are sensitive to the details of the interaction potentials between the colliding systems over an extended range of internuclear separations. Recent experiments with chromium [4,5,6,7] emphasize the need for theoretical studies of Cr scattering properties. The interest in cooling Cr stems from its particular properties; in its ground state 7 S 3 , it possesses a very large magnetic moment, 6 µ B (µ B : Bohr magneton), making it an ideal atom for buffer-cooling in a purely magnetic trap [7], as well as for magneto-optical trapping [4]. In addition, anisotropic long-range interactions, such as chromium's magnetic dipole-dipole interactions, may lead to novel phenomena in BECs [9,10]. The existence of a stable fermionic isotope, 53 Cr, opens the possibility of obtaining fermionic degenerate gas using sympathetic cooling. Chromium was also used in a new cooling scheme [5], where ultracold chromium atoms were loaded from a MOT into an Ioffe-Pritchard magnetic trap, and cooled below 100µK. However, a not so-desirable byproduct of large-spin collision is inelastic "bad" scattering rates that deplete the trap.On the theoretical front, the electronic spectrum of the Cr 2 dimer poses a considerable numerical challenge. Chromium is the first atom in the periodic table with a half-filled d shell (the ground electronic configuration is Cr(3d 5 4s, 7 S)) and the Cr 2 dimer is one of the most extreme cases of multiple metal-metal bonding. To date, the best attempt to calculate its interaction potential curves is a multiconfiguration second-order perturbation theory with complete active space self-consistent field (CASSCF/CASPT2) [11,12]. While some information on the spectroscopy of the ground electronic state ( 1 Σ + g molecular symmetry) exists, there is no data available for the interaction of two maximally spin-stretched Cr atoms in the 13 Σ + g molecular symmetry, i.e. total spin, S = 6. In this communication, we explore the collisional properties of Cr atoms in the cold and ultracold temperature regimes by revisiting the electronic structure of the dimer. More accurate Born-Oppenheimer potenti...

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Non‐LTE iron abundances in cool stars: The role of hydrogen collisions

2016

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In the aim of determining accurate iron abundances in stars, this work is meant to empirically calibrate H-collision cross-sections with iron, where no quantum mechanical calculations have been published yet. Thus, a new iron model atom has been developed, which includes hydrogen collisions for excitation, ionization and charge transfer processes. We show that collisions with hydrogen leading to charge transfer are important for an accurate non-LTE modeling. We apply our calculations on several benchmark stars including the Sun, the metal-rich star {\alpha} Cen A and the metal-poor star HD140283

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Far-ultraviolet absorption spectra of quasars: How to find missing hot gas and metals

Cited by 108 publications

References 0 publications

Oscillator strengths for AsI-III

Oscillator strengths for AsI-III

Collisional properties of trapped cold chromium atoms

Non‐LTE iron abundances in cool stars: The role of hydrogen collisions

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