Simultaneous NICER and NuSTAR observations of the Ultraluminous source NGC 4190 ULX-1

JORGE COMBI; FEDERICO FOGANTINI; ENZO SAAVEDRA; GUSTAVO E. ROMERO; LEANDRO ABAROA; FEDERICO GARCÍA; PEDRO LUQUE ESCAMILLA; JOSEP MARTI; NELSON CRUZ SANCHEZ

ASTRONOMY & ASTROPHYSICS. SUPPLEMENT SERIES (PRINT)

EDP Sciences

Año: 2024

0365-0138

Aims. We present an X-ray analysis of three different XMM-Newton observations together with simultaneous NICER and NuSTARobservations of the ultraluminous X-ray source NGC 4190 ULX-1. Our goal is to constrain the structure of the accretion disk and thegeometrical properties of the source.Methods. We performed temporal and spectral analyses in the 0.4–30 keV energy range in which the source is significantly detectedin dedicated XMM-Newton, NICER, and NuSTAR observations.Results. The temporal analysis shows no flaring activity in the light curves. No pulsation is detected throughout. The source exhibitsa typical ULX spectrum, which can be fitted with two thermal blackbody components plus a Comptonization tail at high energies.The luminosity-temperature (L − T) relation of each thermal spectral component is consistent with the L ∝ T2relation expected froman advection-dominated supercritical disk.Conclusions. We interpret these results as a super-Eddington accreting black hole seen almost face-on. A dense wind ejected fromthe disk obscures the central source, and a hot electron plasma is evacuated through the funnel formed above the hole. Geometricbeaming is responsible for the ULX soft emission, whereas the hard tail is the result of the Comptonization of soft photons by theelectrons ejected through the funnel.