2004/06/24 by V. Beckmann, N. Gehrels, P. Favre +6 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/423708
published as Astrophys.J. 614 (2004) 641-647 · 11 pages, 5 figures, accepted for publication in ApJ
arxiv created 2004/06/24 · openalex publication_date 2004/10/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We present first INTEGRAL and XMM-Newton observations of a Seyfert galaxy, the type 2 AGN NGC 4388. Several INTEGRAL observations performed in 2003 allow us to study the spectrum in the 20 - 300 keV range. In addition two XMM-Newton observations give detailed insight into the 0.2 - 10 keV emission. The measurements presented here and comparison with previous observations by BeppoSAX, SIGMA and CGRO/OSSE show that the overall spectrum from soft X-rays up to the gamma-rays can be described by a highly absorbed (NH = 2.7e23 1/cm2) and variable non-thermal component in addition to constant non-absorbed thermal emission (T = 0.8 keV) of low abundance (7% solar), plus a constant Fe K-alpha and K-beta line. The hard X-ray component is well described by a simple power law with a mean photon index of 1.7. During the INTEGRAL observations the 20 - 100 keV flux increased by a factor of 1.4. The analysis of XMM-Newton data implies that the emission below 3 keV is decoupled from the AGN and probably due to extended emission as seen in Chandra observations. The constant iron line emission is apparently also decoupled from the direct emission of the central engine and likely to be generated in the obscuring material, e.g. in the molecular torus.