The weak absorbing outflow in AGN Mrk 279 : Evidence of supersolar metal abundances

We present analysis and photoionization modeling of the Chandra high-resolution spectrum of Mrk 279. There is clear evidence of an absorbing outflow that is best fit by a two-component model: one with a low-ionization parameter and one with a higher ionization parameter. The column density of the X-ray warm absorber, about log NH = 20, is the smallest known of all active galactic nuclei (AGNs) in which X-ray absorbing outflows are observed. We find that the X-ray and UV/FUV absorbers are part of the same overall outflow. There is some evidence of supersolar carbon, nitrogen, oxygen, and iron in the Chandra spectrum of Mrk 279. While this is not a robust result in itself, Chandra data in combination with the UV data and the pressure equilibrium between two phases of the outflow, support the scenario of supersolar abundances. This is the first case in which supersolar abundances are reported in the nucleus of a normal Seyfert galaxy. The data suggest that the outflow originates from a compact region around the nuclear black hole and that it carries insignificant amounts of mass and energy.