Researchers first noticed the jets emanating from a low-mass star and stellar-mass black hole pairing known as XTE J1550-564, located 17,000 light-years away from the earth, in 1998. Four years later, they detected radio wavelength activity to the west of the pair. It came from a spot on the path of one of the jets, which are made up of matter pulled from the neighboring star, as it traveled away from the black hole. (The second stream moved in the opposite direction.) The team then searched for archived data collected by the Chandra X-ray Observatory in order to track the evolution of both jets. "The ejection of jets from stellar and supermassive black holes is a common occurrence in the universe," remarks study co-author John Tomsick of the University of California, San Diego, "so it is extremely important to understand the process." The stream traveling away from the earth appeared brighter than its earth-bound companion did, the scientists report. For its part, the jet heading our way slowed down owing to resistance from the surrounding interstellar gas before fading out. The team hopes that the findings will help improve models of what is happening around other, larger black holes in other galaxies. Says lead study author Stephane Corbel of the University of Paris VII, "Since the jets came from a stellar black hole in our galaxy, we watched, in only a few years, developments that would have taken thousands of years to occur around a supermassive black hole in a distant galaxy."
The accretion of matter around a black hole can power it to spew out gaseous jets of highly energized particles. Now, for the first time, astronomers have witnessed the entire lifecycle of these streams, from formation to the final fadeout. A report describing the findings appears today in the journal Science.
