Detection of X-ray elongated emission from a ultraluminous X-ray source   in the interacting pair of galaxies NGC 5953/5954
  We present radio through X-ray results of a bright (10^{40} erg/s in the 0.5 to 8.0 keV band) ultraluminous X-ray source (ULX), CXOU J153434.9+151149, in the starburst, interacting pair of galaxies NGC 5953/5954. Chandra image of this ULX shows that it is elongated. From HST/WFPC2/F606W data we have detected a counterpart of the ULX system with M_{F606W} ~-7.1 \pm 0.7 mag. This optical counterpart may be either an O-type supergiant star or a young star cluster. From our Fabry-Perot interferometric observations, we have detected Halpha and [NII](6584 A) diffuse emission, with velocity gradients up to 60 km/s at the astrometric corrected Chandra position of the ULX. Different scenarios have been invoked as to explain the possible nature of CXOU J153434.9+151149. Based on the observed X-ray morphology of the ULX, we determine that the inclination angle to the elongated emission will be ~53 deg. Beaming with this geometry from a stellar-mass black hole system will be inadequate to explain the observed X-ray luminosity of this ULX. Finally, we suggest that mild-beaming from a binary black hole with mass more than 50 solar masses, associated with a young star cluster, is the most favorable scenario that describes the multiwavelength properties of this ULX. Future observations are highly essential to determine the nature of this rare object. 
Margarita Rosado, Kajal K. Ghosh and Isaura Fuentes-Carrera