A CHANDRA OBSERVATION OF THE ULTRALUMINOUS INFRARED GALAXY IRAS 19254-7245 (THE SUPERANTENNAE): X-RAY EMISSION FROM THE COMPTON-THICK ACTIVE GALACTIC NUCLEUS AND THE DIFFUSE STARBURST
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)
- Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
- INAF-Osservatorio Astronomico di Brera, via Brera 28, I-20121 Milano (Italy)
- Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)
We present a Chandra observation of IRAS 19254-7245, a nearby ultraluminous infrared galaxy also known as the Superantennae. The high spatial resolution of Chandra allows us to disentangle for the first time the diffuse starburst (SB) emission from the embedded Compton-thick active galactic nucleus (AGN) in the southern nucleus. No AGN activity is detected in the northern nucleus. The 2-10 keV spectrum of the AGN emission is fitted by a flat power law ({Gamma} = 1.3) and an He-like Fe K{alpha} line with equivalent width {approx}1.5 keV, consistent with previous observations. The Fe K{alpha} line profile could be resolved as a blend of a neutral 6.4 keV line and an ionized 6.7 keV (He-like) or 6.9 keV (H-like) line. Variability of the neutral line is detected compared with the previous XMM-Newton and Suzaku observations, demonstrating the compact size of the iron line emission. The spectrum of the galaxy-scale extended emission excluding the AGN and other bright point sources is fitted with a thermal component with a best-fit kT of {approx}0.8 keV. The 2-10 keV luminosity of the extended emission is about one order of magnitude lower than that of the AGN. The basic physical and structural properties of the extended emission are fully consistent with a galactic wind being driven by the SB. A candidate ultraluminous X-ray source is detected 8'' south of the southern nucleus. The 0.3-10 keV luminosity of this off-nuclear point source is {approx}6 Multiplication-Sign 10{sup 40} erg s{sup -1} if the emission is isotropic and the source is associated with the Superantennae.
- OSTI ID:
- 22086484
- Journal Information:
- Astrophysical Journal, Vol. 759, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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