A Broadband X-ray Analysis and Optical Counterpart Search of IC5052 ULX

Abstract We present broadband X-ray spectral and timing analysis of the Ultra-luminous X-ray source (ULX) in IC5052 using simultaneous XMM-Newtonand NuSTARobservations from 2022, supplemented by archival 2013 XMM-Newtondata. A two-thermal component model, often interpreted as radially-segregated emission from a super-Eddington inner disc and its associated wind, provides a statistically acceptable fit but yields an implausibly high inner disc temperature of kTin ≈ 6.4 keV, inconsistent with even super-Eddington disc models. Including an additional continuum component from either an accretion column or a Comptonizing corona, as motivated by high S/N observations from other ULXs, provides comparable goodness of fit while allowing plausible inner disc temperatures. The accretion column model yields kTin ~ 1.2 keV with the column contributing Fcol ≈ 62% of total flux, while the Comptonizing corona model yields kTin ~ 3.0 keV with a scattered fraction ~1, assuming the hotter disc provides the seed photons. Timing analysis initially challenges both scenarios: the accretion column model places IC5052 ULX where prior results suggest pulsations may be detectable (Fcol ~ 60%), yet none were detected, while the corona model appears inconsistent with its lack of observed short-timescale variability. However, incorporating spectral information relaxes these constraints, allowing both models to remain physically plausible for IC5052 ULX. Finally, using improved Chandraastrometry, we identified a candidate optical counterpart consistent with an evolved high mass donor. A discrepancy between the optical extinction and X-ray fitted absorption suggests localised X-ray absorption.