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

Abstract

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.

Oscillator Strengths for Ultraviolet Transitions in P ii: The Multiplet at 1308 Å

“…While the results of Tayal (2003) and Froese Fischer et al (2006) agree very well, the f -values are nearly twice those given by Hibbert (1988). The importance of P II oscillator strengths in astronomical studies is discussed in the recent compilation by Cashman et al (2017), who prefer using the results from Froese Fischer et al (2006).…”

DLA and sub-DLA metallicity evolution: A case study of absorbers towards Q0338-0005

“…We used the MIDAS Voigt profile fitting FITLYMAN package (Fontana & Ballester 1995) to fit H i column density and low-ionisation lines simultaneously. For the atomic data, laboratory wavelengths and oscillator strengths from (Cashman et al 2017) were used. The FITLYMAN finds the best fit using a χ 2 minimisation routine which fits the following function:…”

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

“…This single value registered an absolute error of 2.41E-01 when compared with both models. Another source of useful results were from Cashman et al (2017), however they graded their comparable Ge results quite lowly (C+ and ungraded), two of the lowest reliability grades available.…”