A theoretical study of the masstemperature relation for clusters of galaxies
Abstract
I derive the masstemperature relation and its time evolution for clusters of galaxies in different cosmologies by means of two different models. The first one is a modification and improvement of a model by Del Popolo & Gambera, namely based upon a modification of the tophat model in order to take account of angular momentum acquisition by protostructures and of an external pressure term in the virial theorem. The second one is based on the merginghalo formalism of Lacey & Cole, accounting for the fact that massive clusters accrete matter quasicontinuously, and is an improvement of a model proposed by Voit, again to take account of angular momentum acquisition by protostructures. The final result is that, in both models, the MT relation shows a break at T~ 34 keV. The behaviour of the MT relation is as usual, M~T^{3/2}, at the highmass end, and M~T^{γ}, with a value of depending on the chosen cosmology. Larger values of γ are related to open cosmologies, while Λcold dark matter (ΛCDM) cosmologies give results of the slope intermediate between the flat case and the open case. The evolution of the MT relation, for a given M_{vir}, is more modest both in flat and open universes in comparison with previous estimates found in the literature, even more modest than what found by Voit. Moreover, the time evolution is more rapid in models with L= 0 than in models in which the angular momentum acquisition by protostructures is taken into account (L≠ 0). The effect of a nonzero cosmological constant is that of slightly increasing the evolution of the MT relation with respect to open models with L≠ 0. The evolution is more rapid for larger values (in absolute value) of the spectral index, n. The masstemperature relation, obtained using the quoted models, is also compared with the data by Finoguenov, Reiprich & Böeringer. The comparison shows that these data are able to rule out very lowΩ_{0} models (<0.3), particularly in the open case, and that a better fit is obtained by ΛCDM models and by CDM models with Ω_{0} > 0.3.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 October 2002
 DOI:
 10.1046/j.13658711.2002.05697.x
 arXiv:
 arXiv:astroph/0205449
 Bibcode:
 2002MNRAS.336...81D
 Keywords:

 galaxies: formation;
 cosmology: theory;
 largescale structure of Universe;
 Astrophysics
 EPrint:
 19 pages