We analyze a high-resolution (R=140 000) spectrum of the bright quasar HE 0001−2340 (z_em=2.26), obtained with ESPRESSO, recently installed at the Very Large Telescope. In particular, we focused on three absorption systems at z=0.45, z=1.65, and z=2.19:

• (i) In the system at z=0.45 we provide an evidence for the velocity sub-structure of the gas, that has Doppler parameters only of the order of ~0.3 km/s. This agrees with the low kinetic temperature T~100K inferred from modelling of the gas physical conditions. We also confirm the partial coverage of the quasar emission-line region by a FeI-bearing cloud.
  
• (ii) In the system at z=2.19 sub-damped Lyman-alpha system we disentangle turbulent and thermal broadening in many components spread over about 400 km/s. We derive an average temperature of 16000i±1300 K, i.e. about twice the canonical value of the Warm Neutral Medium in the Galactic interstellar medium. Comparison with other high-z, low-metallicity absorbers, reveals an anti-correlation between gas temperature and total HI column density.
  
• (iii) We also 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. These values are consistent with the standard Solar ratio, i.e., we do not confirm strong enhancement of heavy isotopes inferred previously from UVES data.

Russian abstract

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