We revisit the Mg isotopic ratios at z = 0.45 and z = 1.65 and constrain them to be ξ = ( 26Mg + 25Mg)/ 24Mg < 0.6 and < 1.4 in these two systems, respectively. Although requiring confirmation, this could be the first observational evidence of a thermal decrease with galactocentric distance in other words, we may be witnessing a thermal transition between the circumgalactic medium and the cooler ISM. A comparison with other high- z, low-metallicity absorbers reveals an anti-correlation between gas temperature and total H I column density. We derive an average temperature of 16 000 ± 1300 K, which is about twice the canonical value of the warm neutral medium in the Galactic interstellar medium (ISM). We disentangle turbulent and thermal broadening in many components spread over about 400 km s −1 in the z ≈ 2.19 sub-damped Lyman- α system. We also compared our spectrum with those obtained with VLT/UVES, covering a total period of 17 years. We analysed three systems at z = 0.45, z = 1.65, and z = 2.19 using multiple-component Voigt-profile fitting. We analysed a high-resolution ( R = 140 000) spectrum of the bright quasar HE 0001−2340 ( z em = 2.26) obtained with ESPRESSO, which was recently installed at the Very Large Telescope. We aim to study several key physical properties of quasar absorption-line systems that are subtly encoded in their absorption profiles and have not yet been thoroughly investigated or constrained. Institut d’Astrophysique de Paris, CNRS-SU, UMR 7095, 98bis bd Arago, 75014 Paris, FranceĮ-mail: Institute, Politekhnicheskaya 26, 194021 Saint Petersburg, RussiaĮuropean Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago 19, Chileĭirection Générale de l’Aviation Civile, CRNA Nord, 9 rue de Champagne, 91200 Athis-Mons, Franceĭepartamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chileĭepartment of Astronomy, University of Geneva, Chemin PegVersoix, SwitzerlandĪims. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes
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