Chandra PKS 1127-145 + radio (VLA) contours
Credit: X-ray: NASA/CXC/A.Siemiginowska (CfA) & J.Bechtold (U. Arizona); Radio: Siemiginowska et al. (VLA)

Ins and Outs of Black Holes

Somehow infall of material often produces large collimated outflows. This is exemplified in active galaxies, where large clouds of gas and, possibly stars and planets fall onto a black hole at the center of the galaxy, and producing an enormous jet of material which can be millions of light years long. Such jets are often called radio jets, since most were discovered using extremely high resolution observations with radio telescopes. The radio emission arises from relatively cool material inside the jet. Now high resolution X-ray images obtainable with the Chandra X-ray observatory show astronomers that radio jets are often X-ray bright, too. The image above shows a false-color X-ray image of the active galaxy PKS1127-145 obtained by Chandra. The bright central source is thought to be emission from a supermassive black hole; the X-ray jet stretches to the upper left of the image. The white lines are the contours of the radio jet, and show that the X-ray emitting and radio emitting material exist together in the jet. At the distance of PKS1127-145, this jet is about 1 million lightyears long. Interestingly astronomers have found that the emission from the core of the galaxy is absorbed by certain atoms in a galaxy between us and PKS1127-145; by measuring the amount of absorption astronomers can deduce the amount of chemical evolution in the intervening galaxy.

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Page Author: Dr. Michael F. Corcoran
Last modified February 11, 2002