Fe K line complex in the nuclear region of NGC253

Abstract

A bright, nearby edge-on starburst galaxy, NGC253, was studied using the Suzaku, XMM, and Chandra X-ray observatories. With Suzaku and XMM we detected complex line structure of Fe K, which is resolved into three lines (FeI at 6.4keV, FeXXV at 6.7keV, and FeXXVI at 7.0keV) around the center of NGC253. Especially, the FeI and FeXXVI lines are the first clear detections, with a significance of >99.99% and 99.89% estimated by a Monte Carlo procedure. Imaging spectroscopy with Chandra revealed that the emission is distributed in ∼60arcsec2 region around the nucleus, which suggests that the source is not only the buried active galactic nucleus. The flux of highly ionized Fe lines can be explained by the accumulation of 10-1000 supernova remnants that are the result of high star-forming activity, while the FeI line flux is consistent with the fluorescent line emission expected with the molecular clouds in the region. © 2011. The American Astronomical Society. All rights reserved..