It's the circular streaks that you can see when you look at the overall picture (gravity's effect on light). As far as I remember, it's a way of detecting a celestial body of significant weight that we can't actually see with a telescope.
Just looks like you had some around your central point.
oh, I see what your saying. Actually I didn't make it look that way for the sake of gravitational lensing, i did that just because it seemed more realistic to me, i really dunno. But thank you very much for your comment