A Suzaku, NuSTAR, and XMM-Newton view on variable absorption and relativistic reflection in NGC 4151

I present a dedicated study of the compact processes in the nearby Seyfert galaxy NGC 4151 including the complex circumnuclear absorbers, and the nature and geometry of its X-ray source, the corona. I also touch upon the extended X-ray emission that gets ionized by the compact source. We disentangle relativistically blurred X-ray disk reflection from complex line-of-sight absorption, using a suite of Suzaku, NuSTAR, and XMM-Newton observations. Extending upon arlier published work, we pursue a physically motivated model using the latest angle-resolved version of the lamp-post geometry reflection model relxillCp_lp together with a Comptonization continuum. We use a long-look simultaneous Suzaku/NuSTAR observation to develop a baseline model that we apply to all remaining observations. We model the reflected emission as a combination of lamp-post components at the heights of 1.2 and 15.0 gravitational radii. We argue for a vertically extended corona as opposed to two compact and distinct primary sources. We also find two neutral absorbers (one full-covering and one partial-covering), an ionized absorber (log xi = 2.8), and a highly-ionized ultra-fast outflow, which have all been reported previously. The bulk of the spectral variability between 1 keV and 6 keV can be  accounted for by changes in the column density of both neutral absorbers, which appear to be degenerate and inversely correlated with the variable hard continuum component flux. We track variability in absorption on both short (2 d) and long (1 yr) timescales; the observed evolution is either consistent with changes in the absorber structure (clumpy absorber at distances ranging from the broad line region (BLR) to the inner torus or a dusty radiatively driven wind) or a geometrically stable neutral absorber that becomes increasingly ionized at a rising flux level. The soft X-rays below 1 keV are dominated by photoionized emission from extended gas that may act as a warm mirror for the nuclear radiation.

Tobias Beuchert — University of Erlangen/Remeis Observatory, Germany
Thursday 20 April 2017, 12:00
Location: C4.174