--Edwin Hubble
NAVIGATE STO:
COVER
GLOBAL LINKS
SOLAR SYSTEM
DEEP SPACE
ROCKETS
SATELLITES
SHUTTLES
SPACE STATION
ASTRONAUTS
'The important thing is not to stop questioning. Curiosity has its own reason for existing.'
-- Albert Einstein
© 2002
Space Today Online
E-mail.
SPACE TODAY ONLINE ~~ COVERING SPACE FROM EARTH TO THE EDGE OF THE UNIVERSE
Quasars
What Are Quasars?
The Chandra X-ray Telescope, orbiting above Earth, has recorded an image of twin quasars.
Quasar Pair Q2345+007A & B
Credit: NASA/SAO/CXC/P.Green et al
Referred to by astronomers as Q2345+007 A and Q2345+007 B, they are not identical twins. Becuase they are not identical, it is unlikely that they are an optical illusion.
The twins probably were created when galaxies merged.
Astronomers say that when galaxies collide, gas flows onto the central supermassive black holes of each of the galaxies, resulting in two quasars.
The light from this quasar pair started its journey toward Earth 11 billion years ago. The galaxies were about three times closer together then than they are now, so collisions were much more likely.
Quasar pairs that appear to be close to one another and at the same distance from Earth often turn out to be an illusion -- a gravitationally lensed system. In such instances, the image of a single quasar would have been split into two or more images as light was bent and focused on its way to Earth by the gravity of an intervening massive object like a galaxy, or a cluster of galaxies.
Originally, Q2345+007 A and B had been thought to be a gravitational-lens illusion because of similar patterns in the spectrum of their optical and ultraviolet light. However, astronomers found no galaxy or cluster of galaxies betwen Earth and the pair.
Astronomers then used Chandra to search for a new kind of "dark cluster" that might have no hot gas and, thus, no stars. Such a dark-matter cluster would be invisible to optical and ultraviolet telescopes, but visible to X-rays telescopes.
The Chandra X-ray Telescope found no such dark cluster. Astronomers using Chandra also discovered that the X-rays coming from the two quasars were different, suggesting that they are distinct objects, not a mirage.
The twin quasars are in the area of Earth's sky known as the constellation Pisces. The 18-hour Chandra observations were made May 26 and June 27, 2000.
The colors in the photo indicate X-ray energy bands - red is low energy, green is medium energy, and blue is high energy.
The Chandra X-ray Observatory Center is at the Harvard-Smithsonian Center for Astrophysics at Cambridge, Massachusetts.
Learn more about the quasar pair Q2345+007A and B: Learn more from Chandra Images: Learn more about Quasars and Active Galaxies:X-ray Astronomy Field Guide: Quasars and Active Galaxies
Learn more about Chandra: Return to the Deep Space main page
Questions and Answers: Galaxies, Galaxy Clusters, AGN, and Quasars
