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A CANDIDATE ACTIVE GALACTIC NUCLEUS WITH A PURE SOFT THERMAL X-RAY SPECTRUM.
- Source :
-
Astrophysical Journal . 6/20/2012, Vol. 752 Issue 2, p1-1. 1p. - Publication Year :
- 2012
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Abstract
- We report the discovery of a candidate active galactic nucleus (AGN), 2XMM J123103.2+110648 at z = 0.13, with an X-ray spectrum represented purely by soft thermal emission reminiscent of Galactic black hole (BH) binaries in the disk-dominated state. This object was found in the second XMM-Newton serendipitous source catalog as a highly variable X-ray source. In three separate observations, its X-ray spectrum can be represented either by a multicolor disk blackbody model with an inner temperature of kTin ≈ 0.16-0.21 keV or a Wien spectrum Comptonized by an optically thick plasma with kT ≈ 0.14-0.18 keV. The soft X-ray luminosity in the 0.5-2 keV band is estimated to be (1.6-3.8) × 1042 erg s–1. Hard emission above ∼2 keV is not detected. The ratio of the soft to hard emission is the strongest among AGNs observed thus far. Spectra selected in high/low-flux time intervals are examined in order to study spectral variability. In the second observation with the highest signal-to-noise ratio, the low-energy (below 0.7 keV) spectral regime flattens when the flux is high, while the shape of the high-energy part (1-1.7 keV) remains unchanged. This behavior is qualitatively consistent with being caused by strong Comptonization. Both the strong soft excess and spectral change consistent with Comptonization in the X-ray spectrum imply that the Eddington ratio is large, which requires a small BH mass (smaller than ∼105M☼). [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 752
- Issue :
- 2
- Database :
- Academic Search Index
- Journal :
- Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 97997863
- Full Text :
- https://doi.org/10.1088/0004-637X/752/2/154