From: NASA HQ
Posted: Friday, June 16, 2006
Astronomers using NASA's Chandra X-ray Observatory for research are hosting a media teleconference at 1 p.m. EDT Wednesday, June 21, to explain how black holes light up the universe.
Reporters must call the Chandra Press Office at 617-496-7998 or email firstname.lastname@example.org to participate. Images and graphics supporting the briefing will be posted at the start of the briefing on the Web at:
Audio of the event will be streamed live on the Web at:
- Jon Miller, assistant professor, University of Michigan, Ann Arbor
- John Raymond, astrophysicist, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.
- Meg Urry, professor, Yale University, New Haven, Conn.
A video file about the discovery will air on NASA TV. For NASA TV downlink and scheduling information, visit: http://www.nasa.gov/ntv
For information about NASA and agency programs, visit:
Although disk accretion onto compact objects - white dwarfs, neutron stars, and black holes - is central to much of high energy astrophysics, the mechanisms which enable this process have remained observationally elusive. Accretion disks must transfer angular momentum for matter to travel radially inward onto the compact object. Internal viscosity from magnetic processes and disk winds can in principle both transfer angular momentum, but hitherto we lacked evidence that either occurs. Here we report that an X-ray-absorbing wind discovered in an observation of the stellar-mass black hole binary GRO J1655-40 must be powered by a magnetic process that can also drive accretion through the disk. Detailed spectral analysis and modeling of the wind shows that it can only be powered by pressure generated by magnetic viscosity internal to the disk or magnetocentrifugal forces. This result demonstrates that disk accretion onto black holes is a fundamentally magnetic process.
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