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The hard X-ray source IGR J13550-7218 is a new AGN

ATEL # 2563; R. Landi, L. Bassani (IASF/INAF Bologna), A. Bazzano, F. Capitanio (IASF/INAF Rome), A.J. Bird (Univ. Southampton), N. Gehrels (NASA/GSFC), J. Kennea (PSU)
on 14 Apr 2010; 19:30 UT
Password Certification: Raffaella Landi (

Subjects: X-ray, Gamma Ray, AGN, Stars

With reference to the recent detection of the soft X-ray counterpart of the hard X-ray source IGR J13550-7218 (Rodriguez et al. 2010, Atel #2557) we note that the XRT position is compatible with the compact radio source SUMSS J135512.53-721916.2 listed in the Sydney University Molonglo Sky Survey (Mauch et al. 2003, MNRAS, 342, 1117) with a 36 cm flux of 18.8 mJy (see attached figure). This radio source is most likely associated to PMN J1355-7219 or at least provide a great fraction of its 25 mJy flux at 6 cm (Wright et al. 1994, ApJS, 91, 111), (see large error box in the figure). Comparison between these two radio fluxes suggests that the source has a flat radio spectrum (flatter than -0.02 if the 6 cm flux is used as an upper limit).

The X-ray and radio position are also compatible with the 2MASS extended source 2MASX J13551345-7219150, coincident with the USNO-B1.0 object reported in the Atel (also shown in the figure) and associated in NED to the galaxy WKK2657. The source might be radio loud as the loudness parameter R, defined as the ratio between the 6cm and B fluxes, is less or equal 30 (Kellerman et al. 1989, AJ, 98, 1195).

All together the available data indicate that IGR J13550-7218 is a new AGN close to the Galactic plane.

SUMSS image of IGR J13550-7218

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R. E. Rutledge , Editor
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