A STRONG EXCESS IN THE 20-100 keV EMISSION OF NGC 1365

Journal Article · Sun Nov 01 04:00:00 EST 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/705/1/L1· OSTI ID:21378424

Risaliti, G; Elvis, M; Fabbiano, G; Wang, J ^[1]; Braito, V ^[2]; Laparola, V ^[3]; Bianchi, S; Matt, G ^[4]; Maiolino, R ^[5]; Reeves, J ^[6]; Salvati, M ^[7]

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1. Harvard-Smithsonian Center for Astrophysics, 60 Garden St. Cambridge, MA 02138 (United States)
2. Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
3. INAF-IASF, Via U. La Malfa 153, 90146 Palermo (Italy)
4. Dipartimento di fisica, Universita degli Studi 'Roma Tre', Via della Vasca Navale 84, I-00146 Roma (Italy)
5. INAF-Osservatorio Astronomico di Roma via di Frascati, 33 00040 Monte Porzio Catone, Roma (Italy)
6. Astrophysics Group, School of Physical and Geographical Science, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)
7. INAF-Osservatorio di Arcetri, Largo E. Fermi 5, I-50125, Firenze (Italy)

We present a new Suzaku observation of the obscured active galactic nucleus in NGC 1365, revealing an unexpected excess of X-rays above 20 keV of at least a factor approx2 with respect to the extrapolation of the best-fitting 3-10 keV model. Additional Swift-BAT and Integral-IBIS observations show that the 20-100 keV is concentrated within approx1.5 arcmin from the center of the galaxy, and is not significantly variable on timescales from days to years. A comparison of this component with the 3-10 keV emission, which is characterized by a rapidly variable absorption, suggests a complex structure of the circumnuclear medium, consisting of at least two distinct components with rather different physical properties, one of which covers >80% of the source with a column density N {sub H} approx 3-4x10{sup 24} cm{sup -2}. An alternative explanation is the presence of a double active nucleus in the center of NGC 1365.

• OSTI ID: 21378424
• Journal Information: Astrophysical Journal (Online), Journal Name: Astrophysical Journal (Online) Journal Issue: 1 Vol. 705; ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DENSITY
ELECTROMAGNETIC RADIATION
EMISSION
ENERGY RANGE
EXTRAPOLATION
GALAXIES
IONIZING RADIATIONS
KEV RANGE
KEV RANGE 10-100
MATHEMATICAL SOLUTIONS
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
RADIATIONS
SORPTION
X RADIATION
X-RAY GALAXIES