Multi-wavelength studies of ultra luminous X-ray sources in NGC1427

We present the results on the multi-wavelength studies of point sources and ultra luminous X-ray sources (ULXs) in NGC 1427 using the Chandra, Hubble Space Telescope (HST) and Spitzer missions. NGC 1427 is an elliptical galaxy in Fornax cluster, 13 X-ray sources with net counts >50 have been identified by Chandra observation in 2005. Most of the X-ray sources are well fitted with disk black body than power law model and its X-ray luminosity reaches the ULXs range. We searched for the optical counterparts to these sources in HST archival images and studied the variability. Out of 13 sources, four sources are in the field of view of HST and three of them having potential optical counterparts within less than two arc-seconds. One of the optical counterparts of ULXs exhibits a significant variability of ∼0.3 magnitude between two F475W observations separated by 22 months. While, other counterparts are not variable in the same time scale. Also, these sources are blue in (g-z) colors and their optical luminosity are comparable to the X-ray ones. For some sources, the optical luminosity exceeds the X-ray luminosity. The optical magnitude difference is higher than the reported case of ULXs, indicating that the optical variability connected to the X-ray activity.