Composite image of NGC 4258
Credit: X-ray: NASA/CXC/Univ. of Maryland/A.S. Wilson et al.; Optical: Pal.Obs. DSS; IR: NASA/JPL-Caltech; VLA: NRAO/AUI/NSF

Jet Exhaust

Supermassive black holes at the centers of spiral galaxies generate jets of high energy particles which can be seen to emanate for millions of lightyears from the galaxy. These jets are powerful, and a force to be reckoned with in shaping the intergalactic medium. But how do such jets also shape the interstellar medium within the host galaxy itself? Astronomers believe that the "anomalous arms" of the (relatively) nearby spiral galaxy NGC 4258 may hold the answer to this question. These "anomalous arms" appear in radio and X-ray images, and, unlike "normal" spiral arms, they consist mostly of diffuse gas - they contain very few bright massive stars. The composite image shown above shows a composite view of NGC 4258 throughout the electromagnetic spectrum, from radio (in purple), infrared (in red), optical (yellow), to X-ray (blue). Using these data, along with observations with the XMM-Newton X-ray observatory, astronomers have built a convincing case that the anomalous arms are produced by the interaction of the galaxy's disk with of a "cocoon" of hot gas produced by NGC 4258's jets.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:11:21 EDT

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