X-ray astronomy
A scope named Chandra
Black holes revealed
Dark matter detailed
Neutron stars


This active galaxy, NGC 1068, with a black hole at the center, was taken with Rosat's X-ray telescope. The center is about 6,000 light years across. Move the mouse over the image to see a computer simulation of what Chandra might see if the X-rays come from a jet.

(Blurry image) Rosat archive, the Laboratory for High Energy Astrophysics at NASA/Goddard Space Flight Center. (Chandra simulation): based on Very Large Array data, courtesy of Andrew Wilson, University of Maryland.


Black holy smokes
One of the most exciting uses of Chandra will be to "see" something that can't be seen -- black holes. The evidence for black holes consists of images showing disks of hot gas being swept up by the black hole's gravitational pull. Once the matter gets close to the black hole, the hole's intense gravitation causes a bending of time and space that ensures that no further evidence will emerge. a computer simulation of what Chandra might see if the X-rays come from a jet

Chandra is not a magician, so it won't be able to see black holes. But that hot gas getting sucked into oblivion does emit X-rays, and so the telescope should return more detail on what's happening immediately surrounding the hole, which would tell us about these weird regions themselves.

Kimberly Weaver, an astrophysicist at Goddard Space Flight Center in Maryland, plans to do some of these studies. She suspects that the X-rays produced near black holes may arise in a giant jet (move the mouse on the image above to see a computer representation).

These jets are "a few thousand light years long -- about one-tenth the size of a galaxy, or slightly smaller," says Weaver.

They're big -- and powerful, producing roughly one billion times as much energy as our sun! While the sun creates energy by fusing lighter atoms into heavier atoms, these massive displays of X-rays get power from another source. Weaver says the energy is liberated when radiation strikes layers of gases, or when fast electrons run into low-energy photons and give them enough energy to turn into X-rays.

Observations scheduled with Chandra should help pin down the answer, especially when combined with observations of radio waves emitted by the same galaxies. Says Weaver, "If the X-ray jets look like the radio jets, whatever is emitting the X-rays is also the process that emits the radio jets. If not, we know it's another process."

Compared to dark matter, black holes are positively obviously evident.

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The Why Files
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