Atomic data for x-ray astrophysics

Kallman, T. R.; Palmeri, P.

doi:10.1103/revmodphys.79.79

Cited by 158 publications

(108 citation statements)

References 768 publications

(788 reference statements)

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“…Differences are yet expected, since the N i,obs values are affected by line emission partly filling up the absorption lines. Furthermore, the available atomic data keep evolving A76, page 10 of 14 and are still subject to uncertainties which may affect the analysis (Kallman & Palmeri 2007). The ions from Fe IV to Fe VIII having a large uncertainty, they have been excluded from the comparison.…”

Section: Discussionmentioning

confidence: 99%

The thermal instability of the warm absorber in NGC 3783

Goosmann

Holczer

Mouchet

et al. 2016

A&A

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Context. The X-ray absorption spectra of active galactic nuclei frequently show evidence of winds with velocities in the order of 10 3 km s −1 extending up to 10 4 km s −1 in the case of ultra-fast outflows. At moderate velocities, these winds are often spectroscopically explained by assuming a number of absorbing clouds along the line of sight. In some cases it was shown that the absorbing clouds are in pressure equilibrium with each other. Aims. We assume a photo-ionized medium with a uniform total (gas+radiation) pressure. The irradiation causes the wind to be radiation pressure compressed (RPC). We attempt to reproduce the observed spectral continuum shape, ionic column densities, and X-ray absorption measure distribution (AMD) of the extensively observed warm absorber in the Seyfert galaxy NGC 3783. Methods. We compare the observational characteristics derived from the 900 ks Chandra observation to radiative transfer computations in pressure equilibrium using the radiative transfer code titan. We explore different values of the ionization parameter ξ of the incident flux and adjust the hydrogen-equivalent column density, N 0 H , of the warm absorber to match the observed soft X-ray continuum. From the resulting models we derive the column densities for a broad range of ionic species of iron and neon and a theoretical AMD that we compare to the observations. Results. We find an extension of the degeneracy between ξ and N 0 H for the constant pressure models previously discussed for NGC 3783. Including the ionic column densities of iron and neon in the comparison between observations and data we conclude that a range of ionization parameters between 4000 and 8000 erg cm s −1 is preferred. For the first time, we present theoretical AMDs for a constant pressure wind in NGC 3783 that correctly reproduces the observed level and is in approximate agreement with the observational appearance of an instability region. Conclusions. Using a variety of observational indicators, we confirm that the X-ray outflow of NGC 3783 can be described as an RPC medium in pressure equilibrium. The observed AMD agrees with a uniformly hot or a uniformly cold thermal state. The measured ionic column densities suggest that the wind tends to the uniformly cold thermal state. The occurrence of thermal instability in the warm absorber model may depend on the computational method and the spatial scale on which the radiative transfer is solved.

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Section: Discussionmentioning

confidence: 99%

The thermal instability of the warm absorber in NGC 3783

Goosmann

Holczer

Mouchet

et al. 2016

A&A

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“…Aggarwal et al (2005Aggarwal et al ( , 2008Aggarwal et al ( , 2009Aggarwal et al ( , 2010Aggarwal et al ( , 2011Aggarwal et al ( , 2012aAggarwal et al ( ,b,c,d, 2013a included level energies and multipole rates for transitions within 1snl (n ≤ 5, l ≤ (n − 1)) configurations of helium-like ions with Z = 3−36 (except for Ne IX) using the GRASP code ). However, we show below that because they treated correlation only in a limited way, their energies differ from the experimental values by more than 3 eV, which does not meet the accuracy requirement in the fitting of observed spectra (Kharchenko & Dalgarno 2001;Kallman & Palmeri 2007;Smith 2014;Beiersdorfer 2015).…”

Section: Introductionmentioning

confidence: 97%

“…Furthermore, the high-n dielectronic recombination from the hydrogen-like ions can significantly affect some helium-like line ratios from low-lying (n = 2) transitions (Smith et al 2001). The analysis of the observed spectra requires information for a wide range of atomic parameters, including energy levels and transition rates (Kallman & Palmeri 2007;Smith 2014). …”

Section: Introductionmentioning

confidence: 99%

Energy levels and transition rates for helium-like ions withZ = 10–36

Guo

Wang

et al. 2016

A&A

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Aims. Helium-like ions provide an important X-ray spectral diagnostics in astrophysical and high-temperature fusion plasmas. An interpretation of the observed spectra provides information on temperature, density, and chemical compositions of the plasma. Such an analysis requires information for a wide range of atomic parameters, including energy levels and transition rates. Our aim is to provide a set of accurate energy levels and transition rates for helium-like ions with Z = 10-36. Methods. The second-order many-body perturbation theory (MBPT) was adopted in this paper. To support our MBPT results, we performed an independent calculation using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Results. We provide accurate energies for the lowest singly excited 70 levels among 1snl (n ≤ 6, l ≤ (n − 1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln l (n ≤ 6, l ≤ (n − 1)) configurations of helium-like ions with Z = 10−36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. Conclusions. Our MBPT results for singly excited n ≤ 2 levels show excellent agreement with other elaborate calculations, while those for singly excited n ≥ 3 and doubly excited levels show significant improvements over previous theoretical results. Our results will be very helpful for astrophysical line identification and plasma diagnostics.

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“…Atomic data for absorption lines shorter than 911.753Å from the ground level can be found elsewhere, e.g. Verner et al (1994) and Kallman & Palmeri (2007). 2.…”

Section: Introductionmentioning

confidence: 99%

Atomic Data Revisions for Transitions Relevant to Observations of Interstellar, Circumgalactic, and Intergalactic Matter

Cashman

Kulkarni

Kisielius

et al. 2017

ApJS

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Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753Å (the H I Lyman limit), for key heavy elements (heavier than atomic number 5) of astrophysical interest. In particular, we focus on the transitions of those ions that have been observed in the Milky Way interstellar medium (ISM), the circumgalactic medium (CGM) of the Milky Way and/or other galaxies, and the intergalactic medium (IGM). We provide wavelengths, oscillator strengths, associated accuracy grades, and references to the oscillator strength determinations. We also attempt to compare and assess the recent oscillator strength determinations. For about 22% of the lines that have updated oscillator strength values, the differences between the former values and the updated ones are 0.1 dex. Our compilation will be a useful resource for absorption line studies of the ISM, as well as studies of the CGM and IGM traced by sight lines to quasars and gamma-ray bursts. Studies (including those enabled by future generations of extremely large telescopes) of absorption by galaxies against the light of background galaxies will also benefit from our compilation.

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Atomic data for x-ray astrophysics

Cited by 158 publications

References 768 publications

The thermal instability of the warm absorber in NGC 3783

The thermal instability of the warm absorber in NGC 3783

Energy levels and transition rates for helium-like ions withZ = 10–36

Atomic Data Revisions for Transitions Relevant to Observations of Interstellar, Circumgalactic, and Intergalactic Matter

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