Astronomers recently discovered a surprising, rare example of an “Einstein Cross” splitting and amplifying light from the distant depths of the universe.In this, a giant elliptical galaxy about 6 billion light-years away from Earth distorts and quadruples a bright beam of light coming from a background galaxy located behind it and about 11 billion light-years away from our planet. Divides into parts and makes a cross.
Why are these so rare
- It turns out that gravitational lensing happens everywhere in the universe, mostly in the form of so-called “weak lensing”.
- Creating an Einstein Cross requires a precise alignment of the lensing body and light source and astronomers refer to this as “strong gravitational lensing”.
What is Gravitational Lensing
- It occurs when a massive celestial body, such as a galaxy cluster, causes a sufficient curvature of spacetime for the path of light around it to be visibly bent, as if by a lens.
- The body causing the light to curve is accordingly called a gravitational lens.
- An important consequence of this lensing distortion is magnification, allowing us to observe objects that would otherwise be too far away and too faint to be seen.
Einstein cross:
- Einstein predicted the existence of these crosses back in 1915.
- Einstein’s theory of general relativity describes the way massive objects warp the fabric of the universe, called space-time.
- The latest Einstein Cross has some interesting statistics.
- The main galaxy doing the lensing lies about 5.998 billion light-years away. The distant galaxy that it’s lensing is more than 11.179 billion light-years away.
- Thus, the foreground lensing galaxy is giving an amazing look at a galaxy in the early Universe.
What Makes an Einstein Cross
- When a massive galaxy sits directly “in front of” a more distant background object (such as a galaxy or a quasar) the distribution of matter around that galaxy and its gravitational effect can “bend” the light from the object as it passes by.
- In this case, Earth, the lensing galaxy and the quasar have aligned to perfectly duplicate the quasar’s light, arranging them along a so-called Einstein ring.