Cosmology with the SZ spectrum: Measuring the Universe’s temperature with galaxy clusters Gemma Luzzi, Emanuele D’Angelo, Herve Bourdin, Federico De Luca, Pasquale Mazzotta, Filippo Oppizzi and Gianluca Polenta EPJ Web Conf., 257 (2022) 00028 Published online: 17 January 2022 DOI: 10.1051/epjconf/202225700028