Intrinsic absorption in the QSO first J121442.3+280329

This paper presents an analysis of a Keck HIRES spectrum of the QSO FIRST J121442.3+280329, covering the rest wavelength range from 2300 to 3500 Angstrom. The line of sight toward this quasar (QSO) contains an outflow giving rise to many blueshifted absorption lines. The outflow consists of material with a continuous range of velocities from -1200 to -2800 km s(-1). Significant substructure is present in the absorption line profiles. The spectrum is dominated by absorption lines of Mg II and the singly ionized iron group elements Fe II, Cr II, and Mn II, including absorption lines from excited levels with energies above 30,000 cm(-1) (similar to4 eV). We derive constraints on the physical conditions in the outflow by fitting a model to the observed spectrum that simultaneously optimizes the values for the column densities of all species, the excitation temperature, the shape of the unabsorbed continuum, and the covering factor. By comparing these constraints with ionization models, we conclude that the ionization parameter, density, and column density of the outflow is characterized by -2.0 < log U < -0.7, 7.5 < log n(H) < 9.5, and 21.4 < log N-H < 22.2. These values place the absorbing outflow at a distance between 1 and 30 pc from the QSO core.