Subaru high-resolution spectroscopy of complex metal absorption lines of the quasar HS 1603+3820

We present a high-resolution spectrum of the quasar HS 1603+3820 (z _em = 2.542), observed with the High Dispersion Spectrograph on the Subaru Telescope. This quasar, first discovered in the Hamburg/CfA Quasar Survey, has 11 C IV lines at 1.96 < Z_abs < 2.55. Our spectrum covers eight of the 11 C IV lines at z_abs > 2.29 and resolves some of them into multiple narrow components with b < 25 km s^-1 because of the high spectral resolution R = 45,000, while other lines show broad profiles (b > 65 km s^-1). We use three properties of C IV lines, specifically, time variability, covering factor, and absorption-line profile, to classify them into quasar intrinsic absorption lines (QIALs) and spatially intervening absorption lines (SIALs). The C IV lines at 2.42 < Z_abs < 2.45 are classified as QIALs in spite of their large velocity shifts from the quasar. Perhaps they are produced by gas clouds ejected from the quasar with velocity v_ej = 8000-10,000 km s ^-1. On the other hand, three C IV lines at 2.48 < z_abs < 2.55 are classified as SIALs, which suggests there exist intervening absorbers near the quasar. We, however, cannot rule out QIALs for the two lines at z_abs ∼ 2.54 and 2.55, because their velocity shifts, 430 km s^-1 blueward and 950 km s^-1 redward of the quasar, are very small. The C IV line at z_abs ∼ 2.48 consists of many narrow components and also has corresponding low-ionization metal lines (Al II, Si II, and Fe II). The velocity distribution of these low-ionization ions is concentrated at the center of the system compared with that of the high-ionization C IV ion. Therefore we ascribe this system of absorption lines to an intervening galaxy.