Kanta Fujiwara, Yoshihiro Ueda, Shoji Ogawa, Yuya Nakatani, Jack Miller, Takashi Okajima, T. Kawamuro, Peter Boorman, Luigi Gallo, Misaki Mizumoto, Richard Mushotzky, Hirofumi Noda, Yuichi Terashima, Francesco Tombesi, Bert Vander Meulen, Satoshi Yamada
Abstract We report results from the simultaneous XRISM (183 ks) and NuSTAR (62 ks) observations of the Seyfert 2 galaxy NGC 4388. This active galactic nucleus has the brightest Fe K α line among Compton-thin, obscured sources. To model the reflection continuum and fluorescent lines, we employ an updated version of XCLUMPY and a broad-line region (BLR) model with a disk-like geometry. The profile of the neutral Fe K fluorescent line is well described as the sum of three components convolved with Gaussians with FWHM values of ∼290 km s −1 , ∼1470 km s −1 , and ∼11,100 km s −1 . These line widths correspond to radii of 1.5 pc, 0.060 pc, and 1.0 × 10 −3 pc by assuming Keplerian motion, which we interpret as the dusty torus, its inner edge region, and the BLR, respectively. The data suggest that the Fe K α BLR component is larger than that of H α (FWHM of 4500 km s −1 ) in the polarized optical spectrum, implying that the velocity field of the BLR is dominated by that parallel to the equatorial plane. In addition, Fe XXVI Ly α and Fe XXV absorption lines are detected, characterized by log ξ ∼ 3.50 erg cm s − 1 , log N H ∼ 22.1 cm − 2 , v out ∼ 40 km s −1 , and σ v ∼ 160 km s −1 . We infer that the absorber is gravitationally bound and is possibly associated with a failed wind, consistent with a radiation-driven fountain flow.