Towards converged electron-impact excitation calculations of low-lying transitions in Fe <scp>ii</scp>

Smyth, Ryan; Ramsbottom, Catherine; Keenan, F. P.; Ferland, Gary J.; Ballance, C. P.

doi:10.1093/mnras/sty3198

Cited by 25 publications

(28 citation statements)

References 28 publications

(73 reference statements)

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“…As Model 1 contains a limited five configurations in the target wavefunction expansion, and the 3d orbital had been fixed early in the generation of the structure, this model lacks the flexibility to describe the differing configuration states. Similarly large differences were found for the energy position of the 3p 6 3d 7 4s 2 levels in the Fe-peak evaluations of Fe ii (Smyth et al 2019), Ni iii and Ni iv (Fernandez Menchero et al 2019).…”

Section: Accuracy Of Modelssupporting

confidence: 62%

Electron-impact excitation of Ni II

Dunleavy

Ramsbottom

Ballance

2021

A&A

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Aims: Energy levels, transition probabilities, and oscillator strengths are calculated for the second most abundant iron peak element Ni ii. The difficulty in obtaining an accurate target representation is related to the open d-shell nature of the target, which has a minimum requirement of single and double promotions from the ground state configuration to the n=4 shells. Therefore, in order to achieve an accurate representation of the target ion, we have also included configurations containing the 4d, 5s, and 5p subshells. We have undertaken a study of the electron impact excitation of Ni ii and present here the collision strengths for forbidden and allowed transitions among the lowest 800 fine-structure levels as well as the corresponding Maxwellian-averaged effective collision strengths for a range of astrophysically relevant electron temperatures. Methods: An accurate Ni ii target structure was generated using the modified General-purpose Relativistic Atomic Structure Package (GRASP0) for the lowest lying 1220 jj fine-structure levels, comprising the 11 configurations: 3p 6 3d 9 , 3p 6 3d 8 4s, 3p 6 3d 8 4p, 3p 6 3d 8 4d, 3p 6 3d 8 5s, 3p 6 3d 8 5p, 3p 6 3d 7 4s 2 , 3p 6 3d 7 5s 2 , 3p 6 3d 7 4s4p, 3p 6 3d 7 4s4d, and 3p 4 3d 9 4s4d. The relativistic parallel Dirac atomic R-matrix codes (DARC) were utilised in the scattering calculations to generate the collision strengths for incident electron energies between 0 and 2 Ryds and, by employing infinite dipole and non-dipole limit points, we also generated the effective collision strengths for temperatures in the range from 1000 to 400 000 K. Two separate calculations were performed, both comprised of truncated close-coupling expansions of 800 jj-levels with the first calculation retaining the theoretical ab initio energy levels generated in the GRASP0 evaluations, whereas in the second calculation these energies were shifted to their predicted National Institute of Standards and Technology (NIST) values where possible. This should provide a lower estimate on the uncertainty. Results: Comparisons are made between the radiative data and the collisional cross sections with past theoretical and experimental studies. The effective collision strengths when compared with the most recent published calculations, are found to agree to within 10% for the majority of the transitions considered. In addition, the data are used to model the spectrum of Ni ii and good agreement is found with previous investigations and observations.

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Section: Accuracy Of Modelssupporting

confidence: 62%

Electron-impact excitation of Ni II

Dunleavy

Ramsbottom

Ballance

2021

A&A

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“…We calculate the energy levels of the target states of Ge together with oscillator strengths and A-values for transitions between these states. By comparing with available NIST data, we can gauge the accuracy of the models produced, in a similar manner described for other targets -Fe (Smyth et al 2018), Mo (Smyth et al 2017), Ni andNi (Fernández-Menchero et al 2019). The GRASP0 structure model comprised 14 configurations: 3p 6 3d 10 4s 2 3p 6 3d 10 5s 2 3p 6 3d 10 4s5s 3p 6 3d 10 4p5s 3p 6 3d 10 4p 2 3p 6 3d 10 6s 2 3p 6 3d 10 4s5p 3p 6 3d 10 4p5p 3p 6 3d 10 4d 2 3p 6 3d 10 4s4p 3p 6 3d 10 4s5d 3p 6 3d 10 5f 2 3p 6 3d 10 4s4f 3p 6 3d 10 4s6s resulting in a 64 fine level structure.…”

Section: Atomic Structurementioning

confidence: 98%

“…In recent years iron peak elements have been studied by Smyth et al (2019Smyth et al ( , 2018; Fernández-Menchero et al (2019). FernÃąndez-Menchero et al (2020) have helped bridge the gap in accurate atomic data for trans-iron elements, specifically calculating photoionisation cross sections for Sr, Y + and Zr 2+ .…”

Section: Introductionmentioning

confidence: 99%

Electron-Impact Excitation of Ge iii and Photoionisation of Ge ii

Dunleavy

Ballance

Ramsbottom

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Energy levels, Einstein A-values and oscillator strengths are calculated for doubly-ionised germanium (Ge iii). We have undertaken a study of the electron-impact excitation of Ge iii and have also completed a study of the photoionisation of Ge ii. Ge iii target structures were generated using the relativistic GRASP0 package. Several scattering models were investigated to assess the uncertainty quantification of our results. Initially, the lowest lying 64 jj fine-structure levels were included in the close-coupling expansion resulting from 14 non-relativistic configurations. A second larger model was subsequently generated using the GASP package and incorporated the lowest 589 jj fine-structure levels from 17 non-relativistic configurations. Both the DARC and Breit-Pauli parallel suite of R-matrix collision codes were utilised in the scattering calculations to generate the collision strengths for incident electron-energies between 0 and 5 Rydbergs and subsequently the Maxwellian averaged effective collision strengths for temperatures in the range 1000 to 200000 Kelvin. The photoionisation calculations comprised of two studies, a DARC and a Breit-Pauli calculation incorporating the 250 lowest lying levels. Photoionisation cross sections for Ge ii are presented in the range 0-5 Ryds. Due to the lack of data available in the literature, the present radiative data and electron-impact/photoionisation cross sections are compared between the models presented in this paper. To assess their significance for astrophysics, the data are incorporated into the stellar atmosphere package sterne. Test models for the heavy-metal subdwarf LSIV−14○116 are not affected by the new data, but models for cooler stars may be sensitive to them.

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“…However, their modeled emission line strengths of Fe II and Mg II are found to be largely inconsistent (∼1 dex) with the observed line strengths (see Figures 4 and 9 of Sameshima et al 2017), which indicates that their result may not be reliable. The inconsistency can be because their adopted atomic 371-level Fe + model (Verner et al 1999) may be not accurate (see e.g., Verner et al 2003;Smyth et al 2019;Sarkar et al 2021) and/or their parameter space may not reflect the nature of the BLR. Therefore, to confirm the relation between gas density and Eddington ratio, further investigations are required.…”

Section: Physical Implication Of the Relation Between The Blr Metalli...mentioning

confidence: 99%

Strong correlation between FeII/MgII ratio and Eddington ratio of type 1 Active galactic nuclei

Shin,

Woo,

Nagao

et al. 2021

Preprint

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The Fe II/Mg II line flux ratio has been used as an indicator of the Fe/Mg abundance ratio in the broad line region (BLR) of active galactic nuclei (AGNs). On the basis of archival rest-frame UV spectra obtained via the Hubble Space Telescope and the Sloan Digital Sky Survey, we investigate the Fe II/Mg II ratios of type 1 AGNs at z < 2. Over wide dynamic ranges of AGN properties (i.e., black hole mass, AGN luminosity, and Eddington ratio), we confirm that the Fe II/Mg II ratio strongly correlates with Eddington ratio but not with black hole mass, AGN luminosity, or redshift. Our results suggest that the metallicity in the BLR are physically related to the accretion activity of AGNs, but not to the global properties of galaxies (i.e., galaxy mass and luminosity). With regard to the relation between the BLR metallicity and the accretion rate of AGNs, we discuss that metal cooling may play an important role in enhancing the gas inflow into the central region of host galaxies, resulting in the high accretion rate of AGNs.

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Towards converged electron-impact excitation calculations of low-lying transitions in Fe ii

Cited by 25 publications

References 28 publications

Electron-impact excitation of Ni II

Electron-impact excitation of Ni II

Electron-Impact Excitation of Ge iii and Photoionisation of Ge ii

Strong correlation between FeII/MgII ratio and Eddington ratio of type 1 Active galactic nuclei

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