In section 3. Cosmology
Mapping the hot gas temperature in galaxy clusters using X-ray and Sunyaev-Zel'dovich imaging
Temperature is one of the key properties of the hot ionised gas in the intra-cluster medium (ICM) traditionally obtained from X-ray spectroscopic observations. The thermal Sunyaev-Zel'dovich (tSZ) effect can provide an alternative measurement of the ICM temperature if it is combined with X-rays that measure the gas density. In this paper, the authors use this combination to map the temperature distribution of the ICM in the merging cluster MACS J0717.5+3745 taking advantage of deep and resolved tSZ observations from the New IRAM KIDs Array (NIKA) instrument, and from XMM-Newton. The authors demonstrate the capabilities of their approach and find a good morphological agreement between the temperature maps derived from X-ray data only and their map obtained from the tSZ+X-ray combination.