2016MNRAS.457.2005K

From the Voigt profile fitting analysis of 183 intervening systems at 1.7 z systems (∼75 per cent) display a well-characterized scaling relation between integrated column densities of and with a negligible redshift evolution, when column densities of all the and components are integrated within a given ±150 km/s range centred at the flux minimum. The integrated column density increases with at and , then becomes almost independent of at , with a large scatter: at , , with C₁=-1.90±0.55, C₂=-14.11±0.19 and C₃=14.76±0.17, respectively. The steep (flat) part is dominated by -free (-enriched) systems. Extrapolating the - relation implies that most absorbers with are virtually -free. The - relation does not hold for individual components, clumps or the integrated velocity range less than ±100 km/s. This is expected if the line-of-sight extent of is smaller than and decreases more rapidly than at the larger impact parameter, regardless of the location of the + gas in intergalactic medium filaments or in intervening galactic haloes.