XMM-Newton observations of Abell 2255: a test case of a merger after "core-crossing"

I Sakelliou, Trevor Ponman

Research output: Contribution to journalArticle

22 Citations (Scopus)


It has been known that Abell 2255 is not a relaxed cluster, but it is undergoing a merger. Here, we report on the analysis of the XMM-Newton observations of this cluster. The X-ray data give us the opportunity to reveal the complexity of the cluster, especially its temperature distribution. The integrated spectrum is well fitted by a single-temperature thermal model, indicating a mean temperature of similar to 7 keV. However, the cluster is not isothermal at this temperature: its eastern regions are significantly cooler, at similar to 5.5 keV, whilst towards the west the temperature reaches similar to 8.5 keV. These temperature asymmetries can be explained if Abell 2255 has been assembled recently by the merging of smaller subunits. It is now in the phase after the cores of these subunits have collided (the 'core-crossing' phase) some 0.1-0.2 Gyr ago. A comparison with numerical simulations suggests that it will settle down into a relaxed cluster in similar to(2-3) Gyr.
Original languageEnglish
Pages (from-to)1409-1416
Number of pages8
JournalRoyal Astronomical Society. Monthly Notices
Issue number4
Publication statusPublished - 1 Apr 2006


  • X-rays : galaxies : clusters
  • galaxies : clusters : individual : Abell 2255
  • intergalactic medium


Dive into the research topics of 'XMM-Newton observations of Abell 2255: a test case of a merger after "core-crossing"'. Together they form a unique fingerprint.

Cite this