The properties of X-ray-selected active galactic nuclei. I - Luminosity function, cosmological evolution, and contribution to the diffuse X-ray background

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Astrophysical Journal; (United States)

DOI:https://doi.org/10.1086/170102· OSTI ID:5392766

Maccacaro, T; Della ceca, R; Gioia, I M; Morris, S L; Stocke, J T ^[1]

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1. Osservatorio Astronomico, Bologna (Italy) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA) Bologna, Universita (Italy) CNR, Istituto di Radioastronomia, Bologna (Italy) Observatories of the Carnegie Institution of Washington, Pasadena, CA (USA) Colorado, University, Boulder (USA)

X-ray luminosity functions (XLFs) and their implications for cosmological evolution are determined for 420 X-ray-selected active galactic nuclei (AGN). The local XLFs flatten considerably when L(x) is less than or equal to 5 x 10 to the 42nd ergs/s, and higher-luminosity XLF are demonstrated to fit a power-law approximation. Cosmological evolution in terms of two pure-luminosity evolutionary models is directly supported by model-independent AGN XLF, showing weak evolution when z is less than 0.4 and more pronounced evolution at higher z. The parameter C is determined for the two models, and the values support the 'slower' evolution of these AGN relative to QSOs selected optically. The deevolved XLF best-fit slope is found to be 3.05 for high luminosities and 1.35 for low luminosities, with no evidence of slope changes for other luminosities. 38 refs.

• OSTI ID: 5392766
• Journal Information: Astrophysical Journal; (United States), Journal Name: Astrophysical Journal; (United States) Vol. 374; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BACKGROUND RADIATION
COSMOLOGY
ELECTROMAGNETIC RADIATION
GALACTIC EVOLUTION
GALAXY NUCLEI
IONIZING RADIATIONS
LUMINOSITY
MATHEMATICAL MODELS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
X RADIATION