Rojas Bolivar, Randall A.Randall A.Rojas BolivarWik, Daniel R.Daniel R.WikGiacintucci, SimonaSimonaGiacintucciGASTALDELLO, FabioFabioGASTALDELLOHornstrup, AllanAllanHornstrupWestergaard, Niels-JorgenNiels-JorgenWestergaardMadejski, GrzegorzGrzegorzMadejski2025-02-202025-02-2020210004-637Xhttp://hdl.handle.net/20.500.12386/36116Since the first non-thermal reports of inverse Compton (IC) emission from the intracluster medium (ICM) of galaxy clusters at hard X-ray energies, we have yet to unambiguously confirm IC emission in observations with newer facilities. RXTE detected IC emission in one of the hottest known clusters, Abell 2163 (A2163), a massive merging cluster with a giant radio halo-the presumed source of relativistic electrons IC scattering CMB photons to X-ray energies. The cluster's redshift (z ∼ 0.2) allows its thermal and non-thermal radio emission to fit the field of view of the Nuclear Spectroscopic Telescope Array (NuSTAR), permitting a deep observation capable of confirming or ruling out the RXTE report. The IC flux provides constraints on the average magnetic field strength in a cluster. To determine the global diffuse IC emission in A2163, we fit its global NuSTAR spectrum with four models: single- (1T) and two-temperature (2T), 1T+power-law component (T+IC), and multi-temperature+power law (9T+IC). Each represents different characterizations of the thermal ICM emission, with power-law components added to represent IC emission. We find that the 3-30 keV spectrum can be described by purely thermal emission, with a global average temperature of kT = (11.8 ± 0.2) keV. The IC flux is constrained to <4.0 × 10−12 erg s−1 cm−2 using the 1T+IC model and <1.6 × 10−12 erg s−1 cm−2 with the more physical 9T +IC model, both to 90% confidence levels. Combining these limits with 1.4 GHz diffuse radio data from the VLA, we find the average magnetic field strength to be >0.22 μG and >0.35 μG, respectively, providing the strongest constraints on these values in A2163 to date.STAMPAenArticle10.3847/1538-4357/abcbf72-s2.0-85100320177https://iopscience.iop.org/article/10.3847/1538-4357/abcbf7FIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation