Studying the complex absorption profiles of Si IV in 21 HiBALQSO spectra

• Published in: Journal of physics. Conference series Vol. 565; no. 1; pp. 12020 - 8
• Main Authors: Stathopoulos, D, Danezis, E, Lyratzi, E, Antoniou, A, Popović, L Č, Tzimeas, D, Dimitrijević, M S
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2014
• Subjects: Absorption; Blending; Clouds; Kinematics; Line of sight; Optical thickness; Parameters; Physical properties; Physics; Plasma clouds; Quasars; Resonance; Resonance lines; Silicon; Spectra
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/565/1/012020

We investigate the physical conditions and kinematics of broad absorption line region clouds of Si IV in 21 HiBAL Quasars. We use the Danezis et al. method [1], [2], [3] in order to fit and analyze the broad absorption troughs of Si IV resonance lines in the UV region of the electromagnetic spectrum. We find that the BAL flow is not smooth but instead plasma clouds are formed in it. BAL troughs present multicomponent structure which indicates the existence of more than one absorbing cloud in the line of sight, where every absorbing cloud produces a Si IV doublet. We show that the blending of these doublets produces the apparent broad absorption troughs we observe. One of our main achievements is that we managed to decompose and deblend each complex absorption trough to the individual doublets that it consists of. Apart from that, we succeeded in deblending the resonance lines of every doublet. By achieving accurate fits to the BAL troughs we calculated some physical and kinematical parameters that describe the plasma clouds in the line of sight. These parameters are: the radial outflow velocities of the clouds, the random velocities of ions inside each plasma cloud, the apparent optical depth in the center of every absorption component, the FWHM and the equivalent width. As a final step we correlate these physical parameters in order to draw useful conclusions.