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Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64

W. Zheng·G. A. Kriss·J. X. Wang·M. Brotherton·W. R. Oegerle·W. P. Blair·A. F. Davidsen·R. F. Green·J. B. Hutchings·M. E. Kaiser
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Abstract

We present a moderate-resolution (~20 km/s) spectrum of the mini broad-absorption-line QSO PG1351+64 between 915-1180 A, obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Additional spectra at longer wavelengths were also obtained with the HST and ground-based telescopes. Broad absorption is present on the blue wings of CIII 977, Ly-beta, OVI 1032,1038, Ly-alpha, NV 1238,1242, SiIV 1393,1402, and CIV 1548,1450. The absorption profile can be fitted with five components at velocities of ~ -780, -1049, -1629, -1833, and -3054 km/s with respect to the emission-line redshift of z = 0.088. All the absorption components cover a large fraction of the continuum source as well as the broad-line region. The OVI emission feature is very weak, and the OVI/Lyalpha flux ratio is 0.08, one of the lowest among low-redshift active galaxies and QSOs. The UV continuum shows a significant change in slope near 1050 A in the restframe. The steeper continuum shortward of the Lyman limit extrapolates well to the observed weak X-ray flux level. The absorbers' properties are similar to those of high-redshift broad absorption-line QSOs. The derived total column density of the UV absorbers is on the order of 10^21 cm^-2, unlikely to produce significant opacity above 1 keV in the X-ray. Unless there is a separate, high-ionization X-ray absorber, the QSO's weak X-ray flux may be intrinsic. The ionization level of the absorbing components is comparable to that anticipated in the broad-line region, therefore the absorbers may be related to broad-line clouds along the line of sight.

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W. Zheng, G. A. Kriss, J. X. Wang, M. Brotherton, W. R. Oegerle, W. P. Blair, A. F. Davidsen, R. F. Green, J. B. Hutchings, M. E. Kaiser. 2001-07-30. Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64. https://doi.org/10.1086/323437

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