The XMM deep survey in the CDFS: XI. X-ray spectral properties of 185 bright sources

K. Iwasawa, A. Comastri, C. Vignali, R. Gilli, G. Lanzuisi, W. N. Brandt, P. Tozzi, M. Brusa, F. J. Carrera, P. Ranalli, V. Mainieri, I. Georgantopoulos, S. Puccetti, M. Paolillo

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5 Scopus citations


We present the X-ray spectra of 185 bright sources detected in the XMM-Newton deep survey of the Chandra Deep Field South with the three EPIC cameras combined. The 2-10 keV flux limit of the sample is 2? ×? 10-15 erg s-1 cm-2. The sources are distributed over a redshift range of z? =? 0.1-3.8, with 11 new X-ray redshift measurements included. A spectral analysis was performed using a simple model to obtain absorbing column densities, rest-frame 2-10 keV luminosities, and Fe K line properties of 180 sources at z? > ? 0.4. Obscured AGN are found to be more abundant toward higher redshifts. Using the XMM-Newton data alone, seven Compton-thick AGN candidates were identified, which set the Compton-thick AGN fraction at ≂ 4%. An exploratory spectral inspection method with two rest-frame X-ray colours and an Fe line strength indicator was introduced and tested against the results from spectral fitting. This method works reasonably well to characterise a spectral shape and can be useful for a pre-selection of Compton-thick AGN candidates. We found six objects exhibiting broad Fe K lines out of 21 unobscured AGN of best data quality, implying a detection rate of ∼30%. Five redshift spikes, each with more than six sources, are identified in the redshift distribution of the X-ray sources. Contrary to the overall trend, the sources at the two higher redshift spikes, at z = 1.61 and z = 2.57, exhibit a puzzlingly low obscuration.

Original languageEnglish (US)
Article numberA51
JournalAstronomy and Astrophysics
StatePublished - Jul 1 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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