Possible Lens Arc?
I'm not sure if this has any potential of lens arc / merger / etc..
Any input would help.
This is an Illustris sim (more about this exciting project in this recent GZ blog post). Per design, there are no gravitationally lensed images in Illustris (not enough computing power), so this is more likely some kind of interaction or merger.
Hope this helps, and happy hunting! 😃