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The nature of the "Composite" Seyfert/Star-forming Galaxies

2002/12/13 by F. Panessa, Panessa, F., M. Cappi +16
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #astro-ph

paper · pdf · doi:10.48550/arxiv.astro-ph/0212322

4 pages, 2 figures. To appear in "Carnegie Observatories Astrophysics Series, Vol. 1: Coevolution of Black Holes and Galaxies," ed. L. C. Ho (Pasadena: Carnegie Observatories, http://www.ociw.edu/ociw/symposia/series/symposium1/proceedings.html)

openalex publication_date 2002/12/13 · arxiv created 2003/04/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We present the results obtained with BeppoSAX observations of the three Composite Seyfert/star-forming galaxies: IRAS 20051-1117, IRAS 04392-0123 and IRAS 01072+4954. These sources belong to an enigmatic class of X-ray sources detected in the ROSAT All-Sky Survey (Moran et al. 1996) which is composed of 6 low redshift galaxies. Their optical spectra are dominated by the features of HII galaxies while their X-ray luminosities (< 1042 ergs/s) are typical of Seyfert galaxies. IRAS 20051-1117 shows a 2-10 keV spectrum well described by a power-law with photon index = 1.9 and low intrinsic absorption. This result, the ratio Flux(2-10 keV)/Flux([OIII]) and the significant X-ray variability detected, clearly rule out a Compton thick nature of this source. IRAS 04392-0123 and IRAS 01072+4954, instead, have a BeppoSAX flux a factor of ~ 50-80 smaller than in the previous ROSAT observations, resulting in poor statistics, that prevents detailed modeling.

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