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Simultaneous Ultraviolet and X-ray Observations of the Seyfert Galaxy NGC 4151. I. Physical Conditions in the X-ray Absorbers

S. B. Kraemer·I. M. George·D. M. Crenshaw·J. R. Gabel·T. J. Turner·T. R. Gull·J. B. Hutchings·G. A. Kriss·R. F. Mushotzky·H. Netzer·B. M. Peterson·Ehud Behar
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Abstract

We present a detailed analysis of the intrinsic X-ray absorption in the Seyfert 1 galaxy NGC 4151 using Chandra/HETGS data obtained 2002 May, as part of a program which included simultaneous UV spectra using HST/STIS and FUSE. NGC 4151 was in a relatively low flux state during the observations reported here, although roughly 2.5 times as bright in the 2 --10 keV band as during a Chandra observation in 2000. The soft X-ray band was dominated by emission lines, which show no discernible variation in flux between the two observations. The 2002 data show the presence of a very highly ionized absorber, in the form of H-like and He-like Mg, Si, and S lines, as well as lower ionization gas via the presence of inner-shell absorption lines from lower-ionization species of these elements. The former is too highly ionized to be radiatively accelerated in a sub-Eddington source such as NGC 4151. We find that the lower ionization gas had a column density a factor of ~ 3 higher during the 2000 observation. If due to bulk motion, we estimate that this component must have a velocity of more than 1250 km/sec transverse to our line-of-sight. We suggest that these results are consistent with a magneto-hydrodynamic flow.

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S. B. Kraemer, I. M. George, D. M. Crenshaw, J. R. Gabel, T. J. Turner, T. R. Gull, J. B. Hutchings, G. A. Kriss, R. F. Mushotzky, H. Netzer, B. M. Peterson, Ehud Behar. 2005-07-14. Simultaneous Ultraviolet and X-ray Observations of the Seyfert Galaxy NGC 4151. I. Physical Conditions in the X-ray Absorbers. https://doi.org/10.1086/466522

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