Speaker
Description
Ultraluminous X-ray sources (ULXs) are extragalactic, non-nuclear X-ray point sources with luminosities exceeding the Eddington limit for a 10 solar-mass black hole. These sources are widely believed to be X-ray binaries containing black holes or neutron stars that accrete matter at super-Eddington rates. However, the exact mechanisms and geometry of this accretion process remain poorly understood. Holmberg IX X-1 is a nearby ULX that has been extensively observed in the X-ray waveband by several observatories, including Swift, due to its relatively high flux and proximity. Despite this, optical observations of the source remain limited. In this study, we performed semi-simultaneous X-ray and optical observations of Holmberg IX X-1 using the Swift X-ray Observatory and the Thai National Observatory (TNO). Observations were conducted over three consecutive nights, with about 1-2 hour observation window each night, to monitor the source and investigate its variability across both wavebands. In this presentation, we will report on the variability observed in the X-ray and optical wavebands, assess potential correlations between the datasets, and examine evidence for periodic modulation. The implications of these findings will be discussed.
