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Centaurus A:
A Nearby Elliptical Galaxy With An Active Galactic Nucleus
First observed by Chandra in September 1999, Centaurus
A was an early demonstration of the spectacular science
this powerful X-ray observatory could do. Astronomers
continue to use Chandra to study this elliptical galaxy
(also known as NGC 5128) that contains a spectacular
jet and a core teeming with X-ray emitting
sources.
This Chandra image of Cen A shows a bright central
source: the Active Galactic Nucleus (AGN) suspected of
harboring a supermassive black hole. Chandra also
detects a jet emanating from the core and numerous
point-like X-ray sources, all bathed in diffuse X-rays
produced by several-million-degree gas that fills the
galaxy. A team of scientists, led by Ralph Kraft of the
Smithsonian Astrophysical Observatory, has begun to
study each of these components of X-ray emission from
Cen A. The unprecedented imaging resolution of Chandra
allows scientists for the first time to clearly resolve
each of these distinct components of the X-ray emission
for detailed study.
Over 200 point-like X-ray sources have been identified
and studied in Cen A. Because of their distribution
around the center of the galaxy, it is believed that
most of these sources are X-ray binaries in which a
neutron star or stellar-sized black hole is accreting
matter from a nearby companion star. A few may be
supernova remnants or unrelated, more distant
background galaxies. Comparison of Cen A's X-ray binary
population with populations in other galaxies is
important for understanding the evolutionary history of
galaxies. It is becoming clear that there are
significant variations in the X-ray binary populations
of otherwise similar galaxies. The reason for this is
uncertain, but may be related to differences in the
star formation history or mechanisms for the creation
of X-ray binaries. The observation of the jet has
provided scientists some surprises as well. The X-ray
structure of the jet has been shown to be significantly
different than the radio structure, and the X-ray jet
is much more uneven than originally believed. These
results have cast doubts on simple models of how the
energetic particles ejected from the active nucleus
travel along the jet.
The Cen A image was created from Chandra observations
taken on December 5, 1999 (35,900 seconds) and May 17,
2000 (36, 500 seconds) with the Advanced CCD Imaging
Spectrometer (ACIS) as part of the HRC GTO program.
Other members of this research team include Steve
Murray (PI), Bill Forman, and Christine Jones
(Smithsonian Astrophysical Observatory), Martin
Hardcastle and Diana Worrall (Bristol University UK),
and Julia Kregenow (Wittenberg University).
| Fast Facts for Centaurus A: |
| Credit |
NASA/SAO/R.Kraft et al. |
| Scale |
Image is 10 x 6 arcmin. |
| Category |
Quasars & Active Galaxies |
| Coordinates (J2000) |
RA 13h 25m 28s | Dec -43° 01' 11" |
| Constellation |
Centaurus |
| Observation Dates |
December 5, 1999 and May 17, 2000
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| Observation Time |
20 hours |
| Obs. IDs |
316 and 962
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| Color Code |
Intensity |
| Instrument |
ACIS |
| Also Known As | Cen A, NGC 5128 |
| Distance Estimate |
11 million light years |
| Release Date |
August 06, 2001 |
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