Broadband X-ray spectral study of ultraluminous X-ray source M81 X–6

Abstract

ABSTRACT Ultraluminous X-ray sources (ULXs) are a class of extragalactic, point-like, off-nuclear X-ray sources with X-ray luminosity from ∼1039 to 1041 erg s−1. We investigated the temporal and broadband X-ray spectral properties of the ULX M81 X–6 using simultaneous Suzaku and NuSTAR observations. To understand the nature of the source, we searched for pulsating signals from the source using the NuSTAR observation. However, we failed to identify any strong pulsating signals from the source. Alternatively, the broadband spectral modelling with accreting magnetic neutron star continuum model provides a statistically acceptable fit, and the inferred spectral parameters, and X-ray colours are consistent with other pulsating ULXs. Thus, our analysis suggests that M81 X–6 is another candidate ULX pulsar.