How a black hole throws fastballs

A NASA animation shows how a black hole sends out powerful "bullets" of ionized gas.

By Alan Boyle

X-ray and radio observations have revealed how a black hole winds up and pitches fastballs made of ionized gas at a quarter of the speed of light. That's about 1.6 million times faster than the fastest fastball ever pitched on Earth.

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The pitches were clocked during an outburst from the black hole system H1743-322 in mid-2009. using NASA's Rossi X-Ray Timing Explorer and the National Science Foundation's Very Long Baseline Array. The binary system, 28,000 light-years from Earth in the constellation Scorpius, consists of a normal star and a black hole that are gravitationally bound together. The black hole sucks material in a continuous stream from the star, drawing it down in a swirling disk.

Some of the superheated material radiates away from the black hole's surroundings in two jets that point in opposite directions. Every once in a while, hot ionized gas bunches up into huge "bullets" that are wound up and flung out from the disk. RXTE and the VLBA spotted a couple of the bullets as they sped away in early June 2009.

"Like a referee at a sports game, we essentially rewound the footage on the bullets' progress, pinpointing when they were launched," Gregory Sivakoff of the University of Alberta said Tuesday in a NASA news release. "With the unique capabilities of RXTE and the VLBA, we can associate their ejection with changes that likely signaled the start of the process."

By comparing the X-ray observations of H1743-322 and the radio emissions from the blobs of gas, astronomers were able to figure a timeline for the interactions in the disk and the ejection of the fastballs. Sivakoff presented the research team's findings this week in Austin, Texas, at a meeting of the American Astronomical Society, and a paper on the observations will be published in the Monthly Notices of the Royal Astronomical Society.

"This research provides new clues about the conditions needed to initiate a jet and can guide our thinking about how it happens," said Chris Done, an astrophysicist at the University of Durham in England who was not involved in the study.

Rest in peace, Rossi
The study serves as a sendoff of sorts for the Rossi X-Ray Timing Explorer, which was decommissioned last week after 16 years of science operations. "The spacecraft and its instruments had been showing their age, and in the end RXTE had accomplished everything we put it up there to do, and much more," Tod Strohmayer, RXTE project scientist at NASA's Goddard Space Flight Center, said in the space agency's obituary for the probe.

RXTE played a part in mapping the space-time shift around spinning black holes and neutron stars, detecting a black hole's X-ray "heartbeat," figuring out what's behind our galaxy's X-ray glow, studying a superflare blasted out from the Crab Nebula and observing many other extreme phenomena.

NASA says the 7,000-pound satellite is expected to re-enter the atmosphere and burn up sometime between 2014 and 2023, depending largely on how solar activity affects the decay of its orbit.

More from this week's astronomy meeting:

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Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Source: http://cosmiclog.msnbc.msn.com/_news/2012/01/12/10142697-how-a-black-hole-throws-fastballs

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