We present multi-band photometry covering \sim 5 ^ { \circ } \times 5 ^ { \circ } across \omega Cen collected with the Dark Energy Camera , combined to Hubble Space Telescope and Wide Field Imager data for the central regions .
The unprecedented photometric accuracy and field coverage allowed us to confirm the different spatial distribution of blue and red main-sequence stars , and of red-giant branch ( RGB ) stars with different metallicities .
The ratio of the number of blue to red main-sequence stars shows that the blue main-sequence sub-population has a more extended spatial distribution compared to the red main-sequence one , and the frequency of blue main-sequence stars increases at a distance of \sim 20 \arcmin from \omega Cen center .
Similarly , the more metal-rich RGB stars show a more extended spatial distribution compared to the more metal-poor ones in the outskirts of the cluster .
Moreover , the centers of the distributions of metal-rich and metal-poor RGB stars are shifted in different directions with respect to the geometrical center of \omega Cen .
We constructed stellar density profiles for the blue and red main-sequence stars ; they confirm that the blue main-sequence sub-population has a more extended spatial distribution compared to the red main-sequence one in the outskirts of \omega Cen , as found based on the star number ratio .
We also computed the ellipticity profile of \omega Cen , which has a maximum value of 0.16 at a distance of \sim 8 \arcmin from the center , and a minimum of 0.05 at \sim 30 \arcmin ; the average ellipticity is \sim 0.10 .
The circumstantial evidence presented in this work suggests a merging scenario for the formation of the peculiar stellar system \omega Cen .