Studies on the Relativistic Sunyaev-Zeldovich Effect for Clusters of Galaxies

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1.Multiple-Scattering Effects on the Sunyaev-Zeldovich Effect for Clusters of GalaxiesWe have studied the multiple-scattering effects on the relativistic Sunyaev-Zeldovich effect for clusters of galaxies by using the Fokker-Planck expansion method as well as the numerical integration of the Boltzmann collision term. We have found that the multiple-scattering effect is much less than 1% of the single-scattering contribution for ordinary galaxy clusters. This result gives a support to the validity of the single-scattering approximations that have been used in the previous calculations of the present investigator and his collaborators. With this work, the studies of the relativistic Sunyaev-Zeldovich effect have entered the stage of precision science. Furthermore, the present finding gives great values to the present investigation as an investigation in the field of statistical physics. This work has been published in Monthly Notices of Royal Astronomical Society.2.Sunyaev-Zeldovich Effect for Extremely Hot Clusters of GalaxiesVery recently galaxy clusters with the temperature in excess of 25 keV have been discovered. Therefore, it is very important to carry out the calculation of the Sunyaev-Zeldovich effect for extremely hot clusters of galaxies. The present investigator together with his collaborator has carried out a detailed numerical calculation for the temperature range 1 keV < T < 50 keV, and has presented a detailed numerical table and an accurate analytic fitting formula. This work will be of great value for the forthcoming Sunyaev-Zeldovich effect observations of galaxy clusters. This work has been published in Astronomy and Astrophysics.