Searching for Compton-thick AGNs with XMM-Newton observations

Frontiers in Theoretical and Applied Physics/UAE 2017

Mostafa, R.^1 ; Guainazzi, M.^2 ; Ibrahim, A.^3,4

Fayoum University, Physics Department, Science Faculty, Fayoum, Egypt^1

European Space Research and Technology Centre, Noordwijk, Netherlands^2

Zewail City of Science and Technology, Physics of Earth and Universe, Egypt^3

Cairo University, Faculty of Science, Physics Department, Giza, Egypt^4

关键词: Active galactic nuclei;    Column density;    Detection algorithm;    Emission lines;    Equivalent width;    Neutral gas;    Selection methods;    XMM-Newton observations;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/869/1/012086/pdf
DOI  :  10.1088/1742-6596/869/1/012086

来源: IOP

【 摘 要 】

Most Active galactic nuclei (AGNs) are obscured by large column densities of cold and neutral gas. If the X-ray obscuring matter has a column density equal to or larger than the inverse of the Thomson cross-section (NH≥ σT≈ 1.5×1024cm-2), then the source is identified as a Compton-thick AGN. One of the characteristics of Compton-thick AGN is the presence of Fe K emission line in their spectra with a large equivalent width. Using this criterion with XMM-Newton observations we identified Compton-thick AGNs by following a selection method, the FLEX algorithm, developed by Maccacaro et al [1] to search for X-ray line emitting objects (XLEOs). This technique detects the sources having significant excess of photons resulting from the iron emission line. Here we present the results from applying this method on the 28 highly absorbed AGNs recently detected by Corral et al [2]. Of these 28 AGN, 15 are candidate Compton-thick AGN. We applied the detection algorithm on a pilot sample of 40 XMM-Newton observations. Our results confirm the Compton-thick nature of 14 of Compton-thick AGN, based on the observed properties of the Fe Kα emission line. We use the characteristics of the observed lines to diagnose the AGNs and their environments.