A broadband X-ray view of the ultraluminous sources in the galaxies ESO 501–023 and IC 5052

¹ Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, B1900FWA La Plata, Argentina
² Instituto Argentino de Radioastronomía (CCT La Plata, CONICET; CICPBA; UNLP), C.C.5, (1894) Villa Elisa, Argentina
³ Instituto de Astrofísica de Canarias (IAC), Vía Láctea s/n, La Laguna, 38205 S/C de Tenerife, Spain
⁴ Departamento de Astrofísica, Universidad de La Laguna, La Laguna, E-38205 S/C de Tenerife, Spain
⁵ Departamento de Física (EPS), Universidad de Jaén, Campus Las Lagunillas s/n, A3, 23071 Jaén, Spain

^⋆ Corresponding author; educr@fcaglp.unlp.edu.ar

Received: 9 September 2024
Accepted: 28 November 2024

Abstract

We report the results obtained from the analysis of XMM-Newton and NuSTAR observations of two ultraluminous X-ray sources (ULXs) located in the galaxies ESO 501–023 and IC 5052. To better understand their nature, we studied the spectral and timing behavior of these sources. We used spectral-timing techniques to investigate the presence of possible pulsations in the data. We did not detect any significant pulsations and set upper limits on the pulsed fraction of < 9% for ESO 501–023 ULX and < 11% for IC 5052 X-1. These sources exhibit typical ULX X-ray spectra and can be well fitted with two thermal components plus a Comptonization tail at high energies. To classify the sources, we compared their spectral parameters with those of other well-known ULXs. Our results show that ESO 501–023 ULX is in the broadened disk state and IC 5052 X-1 is in the hard ultraluminous state. Finally, our results suggest that the sources are likely nonmagnetic, supercritically accreting objects fed by companion stars.