In 2014 the NGC 5548 Space Telescope and Optical Reverberation Mapping campaign discovered a two-month anomaly when variations in the absorption and emission lines decorrelated from continuum variations. During this time the soft X-ray part of the intrinsic spectrum had been strongly absorbed by a line-of-sight (LOS) obscurer, which was interpreted as the upper part of a disk wind. Our first paper showed that changes in the LOS obscurer produces the decorrelation between the absorption lines and the continuum. A second study showed that the base of the wind shields the broad emission-line region (BLR), leading to the emission-line decorrelation. In that study, we proposed the wind is normally transparent with no effect on the spectrum. Changes in the wind properties alter its shielding and affect the spectral energy distribution (SED) striking the BLR, producing the observed decorrelations. In this work we investigate the impact of a translucent wind on the emission lines. We simulate the obscuration using XMM-Newton, NuSTAR, and Hubble Space Telescope observations to determine the physical characteristics of the wind. We find that a translucent wind can contribute a part of the He ii and Fe Kα emission. It has a modest optical depth to electron scattering, which explains the fainter far-side emission in the observed velocity-delay maps. The wind produces the very broad base seen in the UV emission lines and may also be present in the Fe Kα line. Our results highlight the importance of accounting for the effects of such winds in the analysis of the physics of the central engine.
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Support for HST program number GO-13330 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. We thank NSF (1816537, 1910687), NASA (17-ATP17-0141, 19-ATP19-0188), and STScI (HST-AR-15018, HST-AR-14556). M.C. acknowledges support from NASA through STScI grant HST-AR-14556.001-A and NASA grant 19-ATP19-0188, and also support from National Science Foundation through grant AST-1910687. M.D. and G.F. and F.G. acknowledge support from the NSF (AST-1816537), NASA (ATP 17-0141), and STScI (HST-AR-13914, HST-AR-15018), and the Huffaker Scholarship. M.M. is supported by the Netherlands Organization for Scientific Research (NWO) through the Innovational Research Incentives Scheme Vidi grant 639.042.525. J.M.G. gratefully acknowledges support from NASA under the ADAP award 80NSSC17K0126. M.V. gratefully acknowledges support from the Independent Research Fund Denmark via grant number DFF 8021-00130.
Dehghanian, Maryam; Ferland, Gary J.; Kriss, G. A.; Peterson, B. M.; Korista, K. T.; Goad, M. R.; Chatzikos, Marios; Guzmán, Francisco; De Rosa, G.; Mehdipour, M.; Kaastra, J.; Mathur, S.; Vestergaard, M.; Proga, D.; Waters, T.; Bentz, M. C.; Bisogni, S.; Brandt, W. N.; Dalla Bontà, E.; Fausnaugh, M. M.; Gelbord, J. M.; Horne, Keith; McHardy, I. M.; Pogge, R. W.; and Starkey, D. A., "Space Telescope and Optical Reverberation Mapping Project. XI. Disk-Wind Characteristics and Contributions to the Very Broad Emission Lines of NGC 5548" (2020). Physics and Astronomy Faculty Publications. 669.