Image: NASA/CXC/A. SIEMIGINOWSKA (CfA) AND J. BECHTOLD (University of Arizona )
Interesting discoveries are often accidental, as new findings from the Chandra X-ray Observatory illustrate. While using x-ray radiation from a distant quasar to study an intervening galaxy, astronomers stumbled upon an exciting characteristic of the quasar itself: a large jet at least a million light-years long shoots out from its center, which houses a supermassive black hole. A report detailing these findings will appear in the May 10 edition of the Astrophysical Journal.
The researchers, led by Anna Siemiginowska of the Harvard-Smithsonian Center for Astrophysics, focused on radiation from quasar PKS 1127-145. According to the team, a series of explosive events near the black hole produced the jet some 10 billion years ago. The jets length and bumpy, inconsistent structure suggest a sustained period of activity punctuated by extreme events near the black hole. The x-rays that make the jet visible to Chandra, Siemiginowska explains, were generated when microwave radiation from the early universe collided with the jets powerful magnetic fields and high-energy beam of particles.
The investigators originally set out to use the quasar as a kind of galactic x-ray machine. On their way to the earth, x-rays from the quasar pass through a galaxy about four billion light-years away. Oxygen and other elements in the interstellar clouds of the galaxy absorb some of these x-rays, dimming them. By measuring the spectrum of the received x-rays, the group was able to estimate the oxygen content of the galaxy. Looking forward, Siemiginowska and her colleagues plan to continue focusing on that line of inquiry, but they note that the appearance of the jet proved an intriguing bonus.