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Department of Physics

Staff profile

Publication details for Prof Martin Ward

Ueno, S., Ward, M. J., O'Brien, P. T., Stirpe, G. M. & Matt, G. (1999). The BeppoSAX observation of IRAS 20210+1121. Nuclear Physics B - Proceedings Supplements 69(1-3): 554-557.

Author(s) from Durham


We have obtained a hard X-ray spectrum of the ultraluminous infrared galaxy IRAS 20210+1121 (z = 0.056), whose optical spectrum is that of a Seyfert 2. The most significant feature is a strong Fe K line at 6.7 (6.5–7.0) keV in the rest-frame with equivalent width about 1 keV. This suggests that the observed X-ray continuum is scattered emission from a completely blocked AGN, a situation similar to that in NGC 1068. However, IRAS 20210+1121 has an observed 2–10 keV luminosity of 4 × 1042 erg s−1 (assuming H0 = 50km s−1 Mpc−1), about ten times higher than NGC 1068. If the scattering efficiencies of NGC 1068 and IRAS 20210 are similar, then this implies the presence of an extremely luminous X-ray source in IRAS 20210.