THE CHANDRA COSMOS-LEGACY SURVEY : SOURCE X-RAY SPECTRAL PROPERTIES

Marchesi, S.; Lanzuisi, G.; Civano, F.; Iwasawa, K., et al. (2016-10-20). THE CHANDRA COSMOS-LEGACY SURVEY : SOURCE X-RAY SPECTRAL PROPERTIES. Astrophysical Journal, 830, (2)
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| Published | English
Authors:
Marchesi, S. ; Lanzuisi, G. ; Civano, F. ; Iwasawa, K. , et al.
Department:
Lund Observatory - Has been reorganised
Abstract:

We present the X-ray spectral analysis of the 1855 extragalactic sources in the Chandra COSMOS-Legacy survey catalog having more than 30 net counts in the 0.5-7 keV band. A total of 38% of the sources are optically classified type 1 active galactic nuclei (AGNs), 60% are type 2 AGNs, and 2% are passive, low-redshift galaxies. We study the distribution of AGN photon index Γ and of the intrinsic absorption based on the sources' optical classification: type 1 AGNs have a slightly steeper mean photon index Γ than type 2 AGNs, which, on the other hand, have average times higher than type 1 AGNs. We find that ∼15% of type 1 AGNs have cm-2, i.e., are obscured according to the X-ray spectral fitting; the vast majority of these sources have 1044 erg s-1. The existence of these objects suggests that optical and X-ray obscuration can be caused by different phenomena, the X-ray obscuration being, for example, caused by dust-free material surrounding the inner part of the nuclei. Approximately 18% of type 2 AGNs have cm-2, and most of these sources have low X-ray luminosities (L2-10keV < 1043 erg s-1). We expect a part of these sources to be low-accretion, unobscured AGNs lacking broad emission lines. Finally, we also find a direct proportional trend between and host-galaxy mass and star formation rate, although part of this trend is due to a redshift selection effect.

Keywords:
galaxies: active ; galaxies: nuclei ; X-rays: galaxies
ISSN:
0004-637X
LUP-ID:
4f47a18e-dbe9-4c9d-8291-985fe7b303ce | Link: https://lup.lub.lu.se/record/4f47a18e-dbe9-4c9d-8291-985fe7b303ce | Statistics

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