摘要：Aims. Outflows in active galaxies (AGNs) are common, although their launching mechanism, location, and physical impact on the host galaxy remain controversial. We conducted a multi-wavelength six-month campaign to observe the nearby Seyfert galaxy NGC 7469 with several observatories in order to better understand and quantify the outflow in this AGN.
Methods. We report on the time-integrated line-resolved X-ray spectrum of NGC 7469 obtained with the Reflection Grating Spectrometer (RGS) on board XMM-Newton. We used the RGS spectrum to discern the many AGN outflow components and applied a global fit to obtain their physical parameters.
Results. We find that the AGN wind can be well described by three narrow velocity components at ~–650, –950, and –2050 km s-1. The RGS clearly resolves the –2050 km s-1 component in C5+ Ly α, while the –650 km s-1 and –950 km s-1 velocities are blended. Similar velocities (±200 km s-1) are resolved in the UV. The H-equivalent column densities of these components are, respectively, NH ~ 7 × 1020, 2.2 × 1021, and 1020 cm-2, for a total of ~3 × 1021 cm-2, which was also measured in 2004, indicating the absorber did not significantly change. The –650 km s-1 component shows a broad ionization distribution (−1 ≲ log ξ ≲ 2,ξ being the ionization parameter in erg s-1 cm). We identify a photo-ionized emission component blue-shifted by ~–450 km s-1, somewhat broad (FWHM = 1400 km s-1), and with −1 ≲ log ξ ≲ 1 erg s-1 cm, which we ascribe to the same outflow that produces the absorption lines. We also find a collisionally ionized component at kT = 0.35 keV that we associate with the circum-nuclear star-formation activity of NGC 7469, as it follows the LFIR/LX ≈ 104 relation found in star forming galaxies. The elemental abundance ratios of C, N, Ne, S, and Fe to O in the outflow tend to be between one and two times solar. Preliminary estimates of the absorber distance from the AGN center suggest it is at least a few pc away from the center, but more advanced methods need to be applied in order to obtain better constraints.
Conclusions. The complex X-ray spectrum of NGC 7469 demonstrates the richness of high energy phenomena taking place in AGN cores. The subtle spectroscopic differences between the various components require deep, high-resolution observations, such as the present RGS spectrum, if one is to resolve them and perform quantitative plasma diagnostics.
关键词：galaxies: active;quasars: absorption lines;galaxies: Seyfert;galaxies: individual: NGC 7469
