Chandra X-ray Observatory - HomeAbout The ChandraEducational MaterialsField GuidePhoto AlbumPress RoomResources
Chandra X-ray Observatory - HomeChandra Photo Album - You are here
ObservatoryImages by DateImages by CategorySky MapConstellationsSpecial FeaturesImage HandoutsScale Bar ImagesTutorial Chandra Images & False Color Note on Cosmic DistanceCosmic Look Back TimeScale & DistanceScale & Angular MeasurementImage Use
Web Site ToolsVisit the Chandra ChroniclesEmail NewsletterSite MapNew & NoteworthyImage Use PolicyQuestions & AnswersGlossaryDownload Guide

Cen A (NGC 5128) in Context

HST of Centaurus A HST image of center of Cen A
NASA/HST/E. Schreier
At the "nearby" distance of 11 million light years, Cen A gives astronomers an excellent opportunity to study the strange and fascinating class of galaxies called active galaxies. Active galaxies are characterized by explosive activity that occurs in the central regions. The energy output of these central regions, called Active Galactic Nuclei, or AGNs, can in many cases affect the appearance of entire galaxies.

In extreme cases, called quasars, an AGN can be a thousand times brighter than the host galaxy. The output from the Cen A AGN is slightly less than that of the entire host galaxy, so it is considered a relatively weak AGN. However, it is much closer to us than any quasar, so it is special.

The source of this central explosive activity is thought to be a supermassive black hole with the mass of many millions of stars. X-rays from AGN's are produced when infalling matter is heated to temperatures of millions of degrees as it approaches the gravitational event horizon. X-ray and gamma-ray observatories provide close-up view of the extreme conditions surrounding supermassive black holes.
 Schematic of Supermassive Black Hole Schematic of Supermassive Black Hole with Jet

The energy radiated by a supermassive black hole can be stupendous as it gobbles up stars. The power of an AGN depends on the mass of the central black hole and the rate at which it swallows or accretes matter. One explanation for the explosive activity of Cen A's central black hole is that a collision with one or more smaller galaxies has provided a generous supply of gas for the supermassive black hole to accrete. The dust lanes seen in optical images that stretch across the middle of the galaxy may be a remnant of such a collision.

Composite of Centaurus A X-ray/Optical composite of Cen A
One of the most intriguing features of supermassive black holes is that they do not suck up ALL the matter that falls within their sphere of influence. Some of the matter falls inexorably toward the black hole, and some explodes away from the black hole in high-energy jets that move at near the speed of light. The X-ray jets in Chandra's image of Cen A extend from the center of the galaxy, out to a distance of more than 15,000 light years.

The presence of a bright X-ray jet means that magnetic fields are continually accelerating electrons to extremely high energies over enormous distances. Exactly how this happens is a major puzzle that Chandra may help to solve.

Return to Centaurus A (25 Oct 99)

Chandra Images: '08 | ' 07 | ' 06 | ' 05 | ' 04 | ' 03 | ' 02 | ' 01 | ' 00 | ' 99 | Images by Category

separator line
CXC Home | Search | Help | Site Map | Image Use Policy | Privacy & Accessibility | Downloads & Plugins
Latest Images | New & Noteworthy | Multimedia | Flash Ecards | Glossary | Q&A

RSS Feed RSS Feed | Podcast Podcast | Blog Blog

[News by email: Chandra Digest]
[Contact us:]
NASA's Home Page Smithsonian's Home Page CXC Home Page Image Map for NASA's, Smithsonian and Chandra's Home Pages
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Cambridge, MA 02138 USA
Phone: 617.496.7941 Fax: 617.495.7356

Text Size:
normal font large font larger font
Chandra X-ray Center, Operated for NASA by the Smithsonian Astrophysical Observatory
This site was developed with funding from NASA under Contract NAS8-39073.
Revised: March 24, 2008