NASA's WISE Mission Captures Black Hole's Wildly Flaring Jet

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News release: 2011-298 Sept. 20, 2011

NASA's WISE Mission Captures Black Hole's Wildly Flaring Jet

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-298&cid=release_2011-298

PASADENA, Calif. -- Astronomers using NASA's Wide-field Infrared Survey Explorer (WISE)
have captured rare data of a flaring black hole, revealing new details about these powerful
objects and their blazing jets.

Scientists study jets to learn more about the extreme environments around black holes. Much has
been learned about the material feeding black holes, called accretion disks, and the jets
themselves, through studies using X-rays, gamma rays and radio waves. But key measurements
of the brightest part of the jets, located at their bases, have been difficult despite decades of
work. WISE is offering a new window into this missing link through its infrared observations.

"Imagine what it would be like if our sun were to undergo sudden, random bursts, becoming
three times brighter in a matter of hours and then fading back again. That's the kind of fury we
observed in this jet," said Poshak Gandhi, a scientist with the Japan Aerospace Exploration
Agency (JAXA). He is the lead author of a new study on the results appearing in the
Astrophysical Journal Letters. "With WISE's infrared vision, we were able to zoom in on the
inner regions near the base of the stellar-mass black hole's jet for the first time and the physics of
jets in action."

The black hole, called GX 339-4, had been observed previously. It lies more than 20,000 light-
years away from Earth near the center of our galaxy. It has a mass at least six times greater than
the sun. Like other black holes, it is an ultra-dense collection of matter, with gravity that is so
great even light cannot escape. In this case, the black hole is orbited by a companion star that
feeds it. Most of the material from the companion star is pulled into the black hole, but some of it
is blasted away as a jet flowing at nearly the speed of light.

"To see bright flaring activity from a black hole, you need to be looking at the right place at the
right time," said Peter Eisenhardt, the project scientist for WISE at NASA's Jet Propulsion
Laboratory in Pasadena, Calif. "WISE snapped sensitive infrared pictures every 11 seconds for a
year, covering the whole sky, allowing it to catch this rare event."

Observing the jet's variability was possible because of images taken of the same patch of sky
over time, a feature of NEOWISE, the asteroid-hunting portion of the WISE mission. WISE data
enabled the team to zoom in on the very compact region around the base of the jet streaming
from the black hole. The size of the region is equivalent to the width of a dime seen at the
distance of our sun.

The results surprised the team, showing huge and erratic fluctuations in the jet activity on
timescales ranging from 11 seconds to a few hours. The observations are like a dance of infrared
colors and show that the size of the jet's base varies. Its radius is approximately 15,000 miles
(24,140 kilometers), with dramatic changes by as large as a factor of 10 or more.

"If you think of the black hole's jet as a firehose, then it's as if we've discovered the flow is
intermittent and the hose itself is varying wildly in size," Poshak said.

The new data also allowed astronomers to make the best measurements yet of the black hole's
magnetic field, which is 30,000 times more powerful than the one generated by Earth at its
surface. Such a strong field is required for accelerating and channeling the flow of matter into a
narrow jet. The WISE data are bringing astronomers closer than ever to understanding how this
exotic phenomenon works.

A video showing variations of the black hole jet, as seen via WISE observations, is online at
http://www.astro.isas.jaxa.jp/~pgandhi/wise_gx339/wise_blackhole_anim.html .

Poshak Gandhi is supported by the JAXA International Top Young Fellowship program. Other
authors of the paper include: A.W. Blain of the University of Leicester, United Kingdom; D.M.
Russell and S. Markoff of the University of Amsterdam; P. Casella of the University of
Southampton, United Kingdom; J. Malzac of Centre National de la Recherche Scientifique and
Université de Toulouse, France; S. Corbel of Université Paris Diderot and Commissariat à
l'énergie atomique Saclay, France; P. D'Avanzo of Istituto Nazionale di Astrofisica, Italy; F.W.
Lewis of Faulkes Telescope Project, Wales; M. Cadolle Bel of the European Space Astronomy
Centre, Spain; P. Goldoni of Laboratoire Astroparticule et Cosmologie, France and
Commissariat à l'énergie atomique Saclay, France; S. Wachter of the California Institute of
Technology, Pasadena, Calif.; D. Khangulyan of the Japan Aerospace Exploration Agency; and
A. Mainzer of JPL.

JPL manages and operated WISE for NASA's Science Mission Directorate in Washington. The
spacecraft was put into hibernation mode after it scanned the sky twice, completing its main
objectives. The mission was selected under NASA's Explorers Program, which is managed by
the agency's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by
the Space Dynamics Laboratory in Logan, Utah; and the spacecraft was built by Ball Aerospace
and Technologies Corp., in Boulder, Colo. Science operations and data processing take place at
the Infrared Processing and Analysis Center at the California Institute of Technology in
Pasadena. More information is online at http://www.nasa.gov/wise and
http://wise.astro.ucla.edu and http://jpl.nasa.gov/wise .

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