Quasar absorption outflows on galactic scales: insights from DESI

ABSTRACT Absorption outflows in quasars play an important role in understanding active galactic nuclei (AGNs) feedback and their influence on galaxy evolution. The unprecedented spectral data provided by the Dark Energy Spectroscopic Instrument (DESI) open new avenues to explore these outflows. We analyse five low-ionization absorption outflow systems in four intermediate-redshift quasars ($2 < z < 3$) using the data obtained by DESI in order to characterize their physical properties and energetics, and also to assess their role in AGNs feedback. We use the spectra from DESI’s Early Data Release to determine the ionic column densities, total hydrogen column densities, electron number densities, and ionization parameters via photoionization modelling and absorption line analysis. We derive the outflows’ distance from the AGN, and their kinematic properties: mass-flow rates, kinetic luminosity, and momentum flux. Our study identifies five distinct minibroad absorption line outflow systems, hosted by four quasars. The identified outflows exhibit hydrogen column densities of $\log (N_{\rm H}) = 20.0\!-\!20.7$ cm−2, ionization parameters of $\log (U_{\rm H}) = -2.7$ to $-2.1$, and electron number densities of $\log (n_{\rm e}) =1.45\!-\!2.85$ cm−2. The distances of the outflows from the central source are between 4.5 and 31 kpc, and the kinetic luminosities range from $2\times 10^{-6}$ to $5\times 10^{-3}$ of the Eddington luminosity. The outflows in J1407 and J1032 show the largest kinetic luminosities, with momentum flux ratios ($\dot{p} / \dot{p}_{\rm rad}$) of about 2 and 0.2, respectively. Our findings highlight the vital role of DESI data in uncovering the diversity and significance of quasar outflows in galaxy evolution.