2006/01/18 by I. Sakelliou, Irini Sakelliou, T. J. Ponman +1 · 31 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Cluster (spacecraft) #Cosmology #Galaxy cluster #Gamma-ray bursts and supernovae #Isothermal process #Phase (matter) #Pulsars and Gravitational Waves Research #Thermal #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2006.10080.x
published in Monthly Notices of the Royal Astronomical Society 367(4), 1409-1416 (Oxford University Press) · 9 pages, 6 figures, accepted by MNRAS
arxiv created 2006/01/18 · openalex publication_date 2006/03/03 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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 ∼7 keV. However, the cluster is not isothermal at this temperature: its eastern regions are significantly cooler, at ∼5.5 keV, whilst towards the west the temperature reaches ∼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 ∼(2–3) Gyr.