Simultaneous NICER and NuSTAR observations of the Ultraluminous source NGC 4190 ULX-1
Astronomy & Astrophysics(2024)
摘要
We present an X-ray analysis of three different XMM-Newton observations
together with simultaneous NICER and NuSTAR observations of the ultraluminous
X-ray source NGC 4190 ULX-1. Our goal is to constrain the structure of the
accretion disk and the geometrical properties of the source. We performed a
temporal and spectral analyses in the 0.4–30 keV energy range where the source
is significantly detected in dedicated XMM-Newton, NICER and NuSTAR
observations. The temporal analysis shows no flaring activity in the light
curves. No pulsation is detected throughout. The source exhibits a typical ULX
spectrum, which can be fitted with two thermal blackbody components plus a
Comptonization tail at high energies. The luminosity-temperature relation of
each thermal spectral component is consistent with the L ∝ T^2
relation expected from an advection-dominated supercritical disk. We interpret
these results as a super-Eddington accreting black hole seen almost face-on. A
dense wind ejected from the disk obscures the central source, and a hot
electron plasma is evacuated through the funnel formed above the hole.
Geometric beaming is responsible for the ULX soft emission, whereas the hard
tail is the result of Comptonization of soft photons by the electrons ejected
through the funnel.
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