Detecting Black Holes with Gravitational Microlensing

This animation illustrates the concept of gravitational microlensing with a black hole. When the black hole appears to pass nearly in front of a background star, the light rays of the source star become bent due to the warped space-time around the foreground black hole. It becomes a virtual magnifying glass, amplifying the brightness of the distant background star. Unlike when a star or planet is the lensing object, black holes warp space-time so much that it noticeably alters the distant star’s apparent location in the sky. The larger animation shows the brightening and splitting of the image during microlensing. The inset shows the shift of the image caused by a black hole lens. The two images caused by lensing are too close to be spatially resolved, but changing brightness of the two images produce a shift in the position of the source. To illustrate the shift, the inset only shows how the position of the source changes without showing the brightening. Read more: