One of the brightest x-ray sources in the Milky Way seems
MASSIVE BLACK HOLES
February 25, 2000 -- Astronomers are increasingly convinced
that supermassive black holes lie at the centers of most large
galaxies. It's a classic case of truth being stranger than fiction.
Gigantic disks of gas -- called accretion disks -- swirl around
central black holes that weigh in at millions or even billions of
solar masses. As gas in the accretion disk falls into the hole it
heats up and glows so brightly in x-rays that we can detect
them a billion light years away. The cores of these systems,
called active galactic nuclei (AGNs), outshine all of the stars in
the host galaxy by factors of 10 to 1000.
About 10% of all AGNs are stranger still. They
Many aspects of blazars remain a mystery. What
accelerates the material in the jets to relativistic
The answers to some of these questions about distant
galaxies may lie right here in our own Milky
"Cygnus X-3 is a black hole or a neutron star that's
accreting matter from an companion star,"
During an intense flare in 1997, McCollough and
colleagues made a high-resolution radio map of
"When we looked at the images, lo and behold, there
was definitely a one-sided radio jet, about 50
Above: An artist's concept of a high-mass x-ray binary system like Cygnus
X-3. Gas from a massive star feeds the accretion disk of an orbiting
black hole or neutron star. The accreting gas heats up and shines
brightly as an X-ray source.
"Cygnus X-3 may be the first example of a blazar here in our own
"We can't see Cygnus X-3 optically because it's in the galactic plane