How Gravith creates 2 images of a Quasar?

--------- #1404 - Gravitational Lensing creates Multiple Images

- Attachments : Gravitational lensing

- Quasars are the extremely bright cores of distant galaxies. Their intense light takes billions of years to get to us. Quasars are unique to the evolution of the early Universe. They don’t occur in today’s expanded Universe. Their light travels for a long time and a long way. What happens when their light somehow takes a different path to reach us? What happens when it takes longer for light to travel a longer path? Does one image arrive before the other? Could we see two images of the same thing?

- Yes, that is exactly what happens with gravitational lensing. When light travels through a gravity lens it takes different paths and creates multiple images. If it was a perfect lens the image would be a ring. If it is a distorted lens it could be an arc, or multiple images of the same object.

- A double image of a Quasar can be seen with a large telescope in the Constellation Ursa Major, the Big Bear; we call it the Big Dipper. The upper-right bowl star is Phad. The lower-right bowl star is Merak. ( In the spring the Big Dipper is upside down relative to the North Star). Now from these 2 stars extend an equal distance into the dark sky. There resides a 17 Magnitude pair of “ stars”. actually the pair are the same Quasar, QSO 0957+561. You are seeing double.

- The Quasar is 7.8 billion lightyears away . It is created by a massive Black hole at the center of a young galaxy. The center is filled with intense starbursts that are brighter than the rest of the galaxy. That light travels 2/3rds of the distance to the edge of the Observable Universe.

- We see two images of the same Quasar because a massive foreground galaxy has bent the light. A similar effect can be seen by looking at a candle through the bottom of a wine glass. You will see multiple images of the flame because the light is bent in different paths traveling through the glass.

- In the case of the Quasar images it is gravity that is bending the light. Light travels in different paths. One path takes 417 days longer to reach us than light form the other path.

- The gravity lens is a massive elliptical galaxy in front of the Quasar ( YGKOW G1). As the light beam passes by near the galaxy it gets bent. Some light gets bent one way and some another way. The beam is focused but takes different paths to reach our telescope.

- Albert Einstein’s Theory of Relativity explains this as the mass bending the fabric of space-time. The mass warps space-time to appear like the bottom of a wine-glass. Light beams pass through the lens taking the lowest energy, quickest path. To the light beam it all appears as a straight line. To an outside observer , us, it appears as a bent path.

- The Double Quasar image was discovered in 1979. The two images are separated by 6 arc-seconds which is about the width of the planet Uranus in the sky. The light spectrum of both images are identical. That is how we know it is the same object. A flicker in light from one image shows up 417 days later in the other image.

- Amazing, an announcement will be made shortly, stay tuned.
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707-536-3272, Saturday, February 11, 2012