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[143.19] Time-Variable Complex Metal Absorption Lines in the Quasar HS1603+3820

T. Misawa, M. Eracleous, J.C. Charlton (Penn State University), A. Tajitsu (Subaru Telescope, NAOJ)

We present a new spectrum of the quasar HS1603+3820 (z_em=2.542) taken 1.28 years (0.36 years in the quasar rest frame) after a previous observation with the High Dispersion Spectrograph on the Subaru telescope, for the purpose of identifying intrinsic narrow absorption lines (NALs). This quasar shows a rich complex of C\;{\sc iv} NALs near the emission redshift. We perform time variability analysis as well as covering factor analysis to separate intrinsic NALs from intervening NALs in 8 C\;{\sc iv} systems. Only one of them, which was already identified as an intrinsic system based on covering factor analysis (Misawa et al. 2003, AJ, 125, 1336), shows a large variation in line strength (W_obs~10.4~{\rm Å}\; arrow 19.1~{\rm Å}) in the interval between the two observations. We speculate that a BAL may be forming in the system (i.e., many narrower lines will blend with each other to make a BAL profile). We illustrate the plausibility of this suggestion with the help of a simulation in which we vary the column densities and covering factors of the NALs. Supposing that a change of ionization state causes the variability, a lower limit can be placed on the electron density (n_e > 3.2\times 10⁴~{\rm cm}^-3) and an upper limit on the distance from the continuum source (r < 6~kpc). On the other hand, if the motion of clumpy gas causes the variability, the crossing velocity and the distance from the continuum source are estimated to be v_cross > 8,000~{\rm km~s}^-1 and r < 0.2~pc, assuming the Murray et al. (1995, ApJ, 451, 498) dynamical model of the accretion disk wind. We acknowledge support from NASA grant NAG5-10817.

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.