Far‐Ultraviolet Spectroscopic ExplorerObservations of the Narrow‐Line Seyfert 1 Galaxy Arakelian 564

We present a 63 ks FUSE observation of the Narrow-Line Seyfert 1 galaxyArakelian 564. The spectrum is dominated by the strong emission in the O VI\lambda\lambda1032, 1038 resonance doublet. Strong, heavily saturatedabsorption troughs due to Lyman series of Hydrogen, O VI and C III \lambda 977at velocities near the systemic redshift of Arakelian564 are also observed. Weused the column densities of O VI and C III in conjunction with the publishedcolumn densities of species observed in the UV and X-ray bands to deriveconstraints on the physical parameters of the absorber through photoionizationmodeling. The available data suggest that the UV and X-ray absorbers inArakelian~564 are physically related, and possibly identical. The combinationof constraints indicates that the absorber is characterized by a narrow rangein total column density N_H and U, centered at log N_H ~ 21 and log U ~ -1.5,and may be spatially extended along the line of sight.Comment: 10 pages, 9 figures; accepted for publication in The Astrophysical Journal, LaTeX emulateapj.st