Testing Unified X-Ray/Ultraviolet Absorber Models with NGC 5548

Abstract

The bright Seyfert galaxy NGC 5548 shows absorption features in its X-ray and UV spectra. The large amount of optical/UV and X-ray monitoring data available for this object makes it an ideal candidate to test our model of a common X-ray/UV absorber. We show that the X-ray/UV absorption is caused by a highly ionized (2.2 < U < 2.8), high column density (N_H = 3.8 × 10²¹ cm^-2) gas situated outside the C IV emitting region (2 × 10¹⁶ cm < r_abs < 2 × 10¹⁸ cm). The gas is outflowing with a mean velocity of 1200±260 km s^-1 and corresponding kinetic luminosity of ∼10⁴³ ergs s^-1. The gas is more highly ionized and has a much larger column density than earlier estimates based on UV data alone. This third example of an X-ray/UV absorber reinforces our earlier conclusion that outflowing, highly ionized gas is common in the inner regions of quasars.