Revealing the High Energy Emission from the Obscured Seyfert Galaxy MCG-5-23-16 with Suzaku
Kunieda, Hideyo; Okajima, Takashi; Yaqoob, Tahir; Fukazawa, Yasushi; Takahashi, Tadayuki; Yamauchi, Makoto; Dewangan, Gulab C.; Awaki, Hisamitsu; Terashima, Yuichi; Reeves, James N.; Miniutti, Giovanni; Inoue, Hajime; Mizuno, Tsunefumi; Watanabe, Shin; Griffiths, Richard; Mushotzky, Richard; Ptak, Andy; Ushio, Masayoshi; Yamasaki, Tomonori; Markowitz, Alex; Gallo, Luigi; Fabian, Andy C.
United States, Japan, United Kingdom, Germany
Abstract
We report on a 100ks Suzaku observation of the bright, nearby (z=0.008486) Seyfert 1.9 galaxy MCG-5-23-16. The broad-band (0.4-100keV) X-ray spectrum allows us to determine the nature of the high energy emission with little ambiguity. The X-ray continuum consists of a cutoff power-law of photon index Γ=1.9, absorbed through Compton-thin matter of column density NH = 1.6 × 1022 cm-2. A soft excess is observed below 1keV and is likely a combination of emission from scattered continuum photons and distant photoionized gas. The iron K line profile is complex, showing narrow neutral iron Kα and Kβ emission, as well as a broad line which can be modeled by a moderately inclined accretion disk. The line profile shows either the disk is truncated at a few tens of gravitational radii, or the disk emissivity profile is relatively flat. A strong Compton reflection component is detected above 10keV, which is best modeled by a combination of reflection off distant matter and the accretion disk. The reflection component does not appear to vary. The overall picture is that this Seyfert 1.9 galaxy is viewed at moderate (∼ 50°) inclination through Compton-thin matter at the edge of a Compton-thick torus covering ∼ 2π steradians, consistent with unified models.