X-ray emission from RX J1720.1+2638 and Abell 267: A comparison between a fossil and a non-fossil system

We present the XMM‐Newton X‐ray analysis of RX J1720.1+2638 and Abell 267, a non‐fossil and a fossil system, respectively. The whole spectrum of both objects can be explained by thermal emission. The luminosities found for RX J1720.1+2638 and Abell 267 in the 2–10 keV band are 6.20+0.04 –0.02 × 1044 and 3.90+0.10 –0.11 ×1044 erg s–1, respectively. The radial profiles show a cool core nature for the non‐fossil system RX J1720.1+2638, while Abell 267 shows a constant behaviour of temperature with radius. Metallicity profiles have also been produced, but no evidence of any gradient was detected due to the large uncertainties in the determination of this parameter. Finally, density and mass profiles were also produced allowing to derive M500 for RX J1720.1+2638 and Abell 267. The masses obtained are high, in the range of (5–7)× 1014 M⊙. The X‐ray properties obtained for both systems are not always in good agreement with what is expected: cool cores are expected for fossil systems, as Abell 267, considering them as and relaxed systems. However, the decrement of the temperature in Abell 267 could start at lower radii. Also the presence of a recent merger in Abell 267, already suggested in the literature, could have increased the central temperature. The non‐fossil system RX J1720.1+2638 actually exhibits a cool core profile, but also evidence of a recent merger has been reported. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)