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M87 Jet:
Chandra Sheds Light on the Knotty Problem of the M87 Jet
NASA's Chandra X-ray Observatory
has given astronomers their most detailed look to date
at the X-ray jet blasting out of the nucleus of M87, a
giant elliptical galaxy 50 million light years away in
the constellation Virgo.
The X-ray image of the jet reveals an irregular,
knotty structure similar to that detected by radio
telescopes and the Hubble Space Telescope. At the
extreme left of the image, the bright galactic nucleus
harboring a supermassive black hole shines. The jet is
thought to be produced by strong electromagnetic forces
created by matter swirling toward the supermassive
black hole. These forces pull gas and magnetic fields
away from the black hole along its axis of rotation in
a narrow jet. Inside the jet, shock waves produce
high-energy electrons that spiral around the magnetic
field and radiate by the "synchrotron" process,
creating the observed radio, optical and X-ray knots.
Synchrotron radiation is caused by high-speed
charged particles, such as electrons, emitting
radiation as they are accelerated in a magnetic
field.
By using the High Energy Transmission Grating (HETG)
with the Advanced CCD Imaging Spectrometer (ACIS)
detector aboard Chandra, the scientists were able to
measure accurately the spectrum, or distribution of the
X-rays with energy. This provided strong support for
the model where electrons are accelerated to high
energies in the knots, radiating X-rays by the
synchrotron process.
The spectrum and intensity of the X-rays from the
galactic nucleus also indicate that this radiation is
not caused by hot gas produced by material falling into
the supermassive black hole. Instead, a high-energy, as
yet unresolved, outflow close to the black hole may be
producing the X-rays by the same synchrotron process
that explains the knots in the jet observed by
Chandra.
A team of astronomers led by Herman Marshall of the
Massachusetts Institute of Technology in Cambridge used
Chandra to observe M87 for 10.6 hours on July 17-18,
2000. According to Marshall, one of the remarkable
findings of the investigation is that the knots near
the core are much brighter in X-rays than the farthest
knots, relative to the optical and radio bands. While
the exact reason for this dimming is unknown, it is
likely to be related to the slowing of the jet, which
was discovered using the Hubble.
| Fast Facts for M87 Jet: |
| Credit |
X-ray: NASA/CXC/MIT/H.Marshall et al. Radio: F. Zhou, F.Owen (NRAO), J.Biretta (STScI) Optical: NASA/STScI/UMBC/E.Perlman et al. |
| Scale |
Image is 32 x 21 arcsec (each panel). |
| Category |
Quasars & Active Galaxies |
| Coordinates (J2000) |
RA 12h 30m 49.40s | Dec +12º 23' 27.90" |
| Constellation |
Virgo |
| Observation Dates |
July 17-18, 2000
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| Observation Time |
11 hours |
| Obs. IDs |
241
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| Color Code |
Intensity |
| Instrument |
ACIS |
| References | H. Marshall et al "A High Resolution X-ray Image of the Jet in M87", http://xxx.lanl.gov/abs/astro-ph/0109160 |
| Distance Estimate |
About 50 million light years |
| Release Date |
September 26, 2001 |
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