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

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Marchesi , S , Lanzuisi , G , Civano , F , Iwasawa , K , Suh , H , Comastri , A , Zamorani , G , Allevato , V , Griffiths , R , Miyaji , T , Ranalli , P , Salvato , M , Schawinski , K , Silverman , J , Treister , E , Urry , C M & Vignali , C 2016 , ' THE CHANDRA COSMOS-LEGACY SURVEY : SOURCE X-RAY SPECTRAL PROPERTIES ' , Astrophysical Journal , vol. 830 , no. 2 , 100 . https://doi.org/10.3847/0004-637X/830/2/100

Title: THE CHANDRA COSMOS-LEGACY SURVEY : SOURCE X-RAY SPECTRAL PROPERTIES
Author: Marchesi, S.; Lanzuisi, G.; Civano, F.; Iwasawa, K.; Suh, H.; Comastri, A.; Zamorani, G.; Allevato, V.; Griffiths, R.; Miyaji, T.; Ranalli, P.; Salvato, M.; Schawinski, K.; Silverman, J.; Treister, E.; Urry, C. M.; Vignali, C.
Contributor: University of Helsinki, Department of Physics
Date: 2016-10-20
Language: eng
Number of pages: 20
Belongs to series: Astrophysical Journal
ISSN: 0004-637X
URI: http://hdl.handle.net/10138/183464
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 Gamma and of the intrinsic absorption N-H,N-z based on the sources' optical classification: type 1 AGNs have a slightly steeper mean photon index Gamma than type 2 AGNs, which, on the other hand, have average N-H,N-z similar to 3 times higher than type 1 AGNs. We find that similar to 15% of type 1 AGNs have N-H,N-z > 10(22) cm(-2), i.e., are obscured according to the X-ray spectral fitting; the vast majority of these sources have L2-10 (keV) > 10(44) 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 N-H,N-z <10(22) cm(-2), and most of these sources have low X-ray luminosities (L2-10 (keV) <10(43) 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 N-H,N-z and host-galaxy mass and star formation rate, although part of this trend is due to a redshift selection effect.
Subject: galaxies: active
galaxies: nuclei
X-rays: galaxies
ACTIVE GALACTIC NUCLEI
DEEP FIELD-SOUTH
STAR-FORMING GALAXIES
SEYFERT 2 GALAXIES
ABSORBING COLUMN DENSITIES
XMM-NEWTON OBSERVATIONS
EVOLUTION SURVEY COSMOS
HEAVILY OBSCURED AGN
COMPTON-THICK AGN
PHOTOMETRIC REDSHIFTS
115 Astronomy, Space science
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