Images by Date
Images by Category
Solar System
White Dwarfs
Neutron Stars
Black Holes
Milky Way Galaxy
Normal Galaxies
Galaxy Clusters
Cosmology/Deep Field
Images by Interest
Space Scoop for Kids
Sky Map
Photo Blog
Top Rated Images
Image Handouts
Fits Files
Image Tutorials
Photo Album Tutorial
False Color
Cosmic Distance
Look-Back Time
Scale & Distance
Angular Measurement
Images & Processing
Image Use Policy
Web Shortcuts
Chandra Blog
RSS Feed
Email Newsletter
News & Noteworthy
Image Use Policy
Questions & Answers
Glossary of Terms
Download Guide
Get Adobe Reader
NGC 3393: NASA's Chandra Finds Nearest Pair of Supermassive Black Holes
NGC 3393
NGC 3393

  • A pair of supermassive black holes has been found in a spiral galaxy (like the Milky Way) for the first time.

  • This galaxy, called NGC 3393, is relatively nearby at a distance of about 160 million light years.

  • These two black holes may be the byproduct of a merger between two galaxies of different sizes a billion or more years ago.

Evidence for a pair of supermassive black holes in a spiral galaxy has been found in data from NASA's Chandra X-ray Observatory. This main image is a composite of X-rays from Chandra (blue) and optical data from the Hubble Space Telescope (gold) of the spiral galaxy NGC 3393. Meanwhile, the inset box shows the central region of NGC 3993 as observed just by Chandra.

The diffuse blue emission in the large image is from hot gas near the center of NGC 3393 and shows low energy X-rays. The inset shows only high energy X-rays, including emission from iron. This type of emission is a characteristic feature of growing black holes that are heavily obscured by dust and gas.

Two separate peaks of X-ray emission (roughly at 11 o'clock and 4 o'clock) can clearly be seen in the inset box. These two sources are black holes that are actively growing, generating X-ray emission as gas falls towards the black holes and becomes hotter. The obscured regions around both black holes block the copious amounts of optical and ultraviolet light produced by infalling material.

At a distance of 160 million light years, NGC 3393 contains the nearest known pair of supermassive black holes. It is also the first time a pair of black holes has been found in a spiral galaxy like our Milky Way. Separated by only 490 light years, the black holes in NGC 3393 are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.

Dubbed "minor mergers" by scientists, such collisions of one larger and another smaller galaxy may, in fact, be the most common way for black hole pairs to form. Until the latest Chandra observations of NGC 3393, however, it has has been difficult to find good candidates for minor mergers because the merged galaxy is expected to look like an ordinary spiral galaxy.

If this was a minor merger, the black hole in the smaller galaxy should have had a smaller mass than the other black hole before their host galaxies started to collide. Good estimates of the masses of both black holes are not yet available to test this idea, although the observations do show that both black holes are more massive than about a million Suns.

Fast Facts for NGC 3393:
Credit  X-ray: NASA/CXC/SAO/G.Fabbiano et al; Optical: NASA/STScI
Release Date  August 31, 2011
Scale  Image is 12.5 arcsec across (about 9,800 light years) | Inset image is 1.6 arcsec across (1260 light years)
Category  Quasars & Active Galaxies
Coordinates (J2000)  RA 10h 48m 23.40s | Dec -25° 09´ 43.00"
Constellation  Hydra
Observation Date  28 Feb. 2004 & 12 March 2011
Observation Time  27 hours 43 min (1 day 3 hours 43 min)
Obs. ID  4868, 12290
Instrument  ACIS
References G.Fabbiano et al, 2011, Nature
Color Code  X-ray: Blue; Optical: Gold
Distance Estimate  About 160 million light years
distance arrow
Visitor Comments (8)

I agree that including the links to the original research paper would be a great add-on to this website.

Posted by Dany Vohl on Thursday, 09.13.12 @ 14:37pm

It is a awesome shot, you develop an excellent work. Thank you for sharing these images with us. The best of luck for you.

Posted by Manuel Uribe on Thursday, 09.13.12 @ 14:27pm

Well done, an excellent discovery.
Best wishes.

Posted by Mark Ballington on Saturday, 09.3.11 @ 06:55am

These pictures are great!!!!!!

Posted by BOB on Friday, 09.2.11 @ 19:45pm

Yes, is there a publication associated with this?

Posted by DG on Friday, 09.2.11 @ 15:50pm

Pretty amazing stuff. Very good pick up by astronomers concerned. Do the two holes merge over time, I wonder? Can they continue to exist side by side?
Excellent work.

Posted by Brian Armour on Thursday, 09.1.11 @ 22:59pm

Suggestion: include the link to the original research paper in the press release.

Posted by Rodrigo on Wednesday, 08.31.11 @ 19:32pm

Amazing, keep up the good work. Best of luck.

Posted by Ishan todi on Wednesday, 08.31.11 @ 13:56pm

Rate This Image

Rating: 3.8/5
(991 votes cast)
Download & Share

More Information
Press Room: NGC 3393
For Kids: NGC 3393
Blog: NGC 3393

More Images
X-ray Image of
NGC 3393
Jpg, Tif

More Images
Animation & Video
X-ray and Optical Images
of NGC 3393

More Animations
Related Images
NGC 6240
NGC 6240
(06 Oct 09)

XTE J1550-564
XTE J1550-564
(03 Oct 02)

Related Information
Related Podcast
Top Rated Images
Chandra Releases 3D Instagram Experiences

Brightest Cluster Galaxies

Timelapses: Crab Nebula and Cassiopeia A