The mass-energy budget of the ionised outflow in NGC 7469

¹ UCL Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK e-mail: ajb@mssl.ucl.ac.uk
² Space Telescope Science Institute, 3800 San Martin Drive, Baltimore, MD 21218, USA
³ Physics Department, Technion, Haifa 32000, Israel
⁴ SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
⁵ School of Physics and Astronomy, Raymond and Beverley Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
⁶ St. John's College Research Centre, St. John's College, University of Oxford, Oxford OX1 3JP, UK

Received: 5 December 2006
Accepted: 6 February 2007

Abstract

Although AGN feedback through ionised winds is of great importance in models of AGN/galaxy coevolution, the mass and energy output via these winds, even in the nearby universe, is poorly understood. The issue is complicated by the wide range of ionisation in the winds, which means that multiwavelength observational campaigns are required to obtain the complete picture. In this paper, we use a ~160 ks XMM-Newton RGS spectrum to get the most accurate view yet of the ionised outflow (warm absorber) in NGC 7469 as seen in X-rays, finding that there is a wide range of ionisation, with log ξ in the range ~0.5-3.5 erg cm s^-1, and two main velocity regimes, at 580-720 and 2300 km s^-1, with the highest velocity gas being the least ionised. The total absorbing column density in the X-rays is of order 3 10²¹ cm^-2. We find that the lowest ionisation phase of the absorber is probably identical with one of the phases of the UV absorber discovered in previous studies. We show that both X-ray and UV absorbers are consistent with an origin near the base of a torus wind, where matter is being launched and accelerated. Calculating the mass outflow rate and kinetic luminosity of all the absorber phases, we demonstrate that the X-ray absorbing gas carries respectively ~90% and 95% of the mass and kinetic energy output of the ionised outflow.