Multiwavelength study of the bright X-ray source population in the interacting galaxies NGC5774/NGC5775

Abstract

A few nearby interacting galaxies are known that host elevated number of ultraluminous X-ray sources. Here we report the results of a multiwavelength study of the X-ray source population in the field of the interacting pair of galaxies NGC5774/NGC5775. A total of 49 discrete sources are detected, including 12 ultraluminous X-ray source candidates. X-ray source positions are mapped onto optical and radio images to search for potential counterparts. Twelve sources in the field have optical counterparts. Optical colors are used to differentiate these sources, which are mostly located outside the optical extent of the interacting galaxies, as potential globular clusters (2), one compact blue dwarf galaxy and quasars (5). We obtained optical spectra of two of the latter, which confirm that they are background quasars. We expect 3 background sources in the field of these two galaxies. These results are used to determine the true X-ray population of these two interacting galaxies, which are connected with two bridges. Two high mass X-ray binaries are detected on these two bridges suggesting their formation through the interaction-induced starformation episode.