Featured Research

from universities, journals, and other organizations

NASA's Chandra finds nearest pair of supermassive black holes

Date:
September 1, 2011
Source:
NASA
Summary:
Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way. Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.

Composite image of spiral galaxy NGC 3393.
Credit: X-ray: NASA/CXC/SAO/G. Fabbiano et al; Optical: NASA/STScI

Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way. Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.

The black holes are located near the center of the spiral galaxy NGC 3393. Separated by only 490 light years, the black holes are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.

"If this galaxy wasn't so close, we'd have no chance of separating the two black holes the way we have," said Pepi Fabbiano of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the study that appears in this week's online issue of the journal Nature. "Since this galaxy was right under our noses by cosmic standards, it makes us wonder how many of these black hole pairs we've been missing."

Previous observations in X-rays and at other wavelengths indicated that a single supermassive black hole existed in the center of NGC 3393. However, a long look by Chandra allowed the researchers to detect and separate the dual black holes. Both black holes are actively growing and emitting X-rays as gas falls towards them and becomes hotter.

When two equal-sized spiral galaxies merge, astronomers think it should result in the formation of a black hole pair and a galaxy with a disrupted appearance and intense star formation. A well-known example is the pair of supermassive black holes in NGC 6240, which is located about 330 million light years from Earth.

However, NGC 3393 is a well-organized spiral galaxy, and its central bulge is dominated by old stars. These are unusual properties for a galaxy containing a pair of black holes. Instead, NGC 3393 may be the first known instance where the merger of a large galaxy and a much smaller one, dubbed a "minor merger" by scientists, has resulted in the formation of a pair of supermassive black holes. In fact, some theories say that minor mergers should be the most common way for black hole pairs to form, but good candidates have been difficult to find because the merged galaxy is expected to look so typical.

"The two galaxies have merged without a trace of the earlier collision, apart from the two black holes," said co-author Junfeng Wang, also from CfA. "If there was a mismatch in size between the two galaxies it wouldn't be a surprise for the bigger one to survive unscathed."

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. Assuming a minor merger occurred, the black holes should eventually merge after about a billion years.

Both of the supermassive black holes are heavily obscured by dust and gas, which makes them difficult to observe in optical light. Because X-rays are more energetic, they can penetrate this obscuring material. Chandra's X-ray spectra show clear signatures of a pair of supermassive black holes.

The NGC 3393 discovery has some similarities to a possible pair of supermassive black holes found recently by Julia Comerford of the University of Texas at Austin, also using Chandra data. Two X-ray sources, which may be due to supermassive black holes in a galaxy about two billion light years from Earth, are separated by about 6,500 light years. As in NGC 3393, the host galaxy shows no signs of disturbance or extreme amounts of star formation. However, no structure of any sort, including spiral features, is seen in the galaxy. Also, one of the sources could be explained by a jet, implying only one supermassive black hole is located in the galaxy.

"Collisions and mergers are one of the most important ways for galaxies and black holes to grow," said co-author Guido Risaliti of CfA and the National Institute for Astrophysics in Florence, Italy. "Finding a black hole pair in a spiral galaxy is an important clue in our quest to learn how this happens."

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

For more information on the Chandra mission and this result, including images and other multimedia, visit: http://chandra.harvard.edu and http://www.nasa.gov/chandra


Story Source:

The above story is based on materials provided by NASA. Note: Materials may be edited for content and length.


Journal Reference:

  1. G. Fabbiano, Junfeng Wang, M. Elvis, G. Risaliti. A close nuclear black-hole pair in the spiral galaxy NGC 3393. Nature, 2011; DOI: 10.1038/nature10364

Cite This Page:

NASA. "NASA's Chandra finds nearest pair of supermassive black holes." ScienceDaily. ScienceDaily, 1 September 2011. <www.sciencedaily.com/releases/2011/09/110901141247.htm>.
NASA. (2011, September 1). NASA's Chandra finds nearest pair of supermassive black holes. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2011/09/110901141247.htm
NASA. "NASA's Chandra finds nearest pair of supermassive black holes." ScienceDaily. www.sciencedaily.com/releases/2011/09/110901141247.htm (accessed October 23, 2014).

Share This



More Space & Time News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Russian Cosmonauts Kick Off Final Spacewalk of 2014

Russian Cosmonauts Kick Off Final Spacewalk of 2014

Reuters - US Online Video (Oct. 22, 2014) — Russian cosmonauts Maxim Suraev and Alexander Samokutyaev step outside the International Space Station to perform work on the exterior of the station's Russian module. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
Comet Siding Spring Grazes Mars' Atmosphere

Comet Siding Spring Grazes Mars' Atmosphere

Newsy (Oct. 19, 2014) — A comet from the farthest reaches of the solar system passed extremely close to Mars this weekend, giving astronomers a rare opportunity to study it. Video provided by Newsy
Powered by NewsLook.com
Latin America Launches Communications Satellite

Latin America Launches Communications Satellite

AFP (Oct. 17, 2014) — Argentina launches a home-built satellite, a first for Latin America. It will ride a French-made Ariane 5 rocket into orbit, and will provide cell phone, digital TV, Internet and data services to the lower half of South America. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
This Week @ NASA, October 17, 2014

This Week @ NASA, October 17, 2014

NASA (Oct. 17, 2014) — Power spacewalk, MAVEN’s “First Light”, Hubble finds extremely distant galaxy and more... Video provided by NASA
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins