Featured Research

from universities, journals, and other organizations

Astronomers Measure Mass Of Smallest Black Hole In A Galactic Nucleus

Date:
March 2, 2005
Source:
Ohio State University
Summary:
A group led by astronomers from Ohio State University and the Technion-Israel Institute of Technology have measured the mass of a unique black hole, and determined that it is the smallest found so far.

NGC 4395.
Credit: Photo credit: Allan Sandage, Carnegie Institution

Washington, DC - A group led by astronomers from Ohio State University and the Technion-Israel Institute of Technology have measured the mass of a unique black hole, and determined that it is the smallest found so far.

Related Articles


Early results indicate that the black hole weighs in at less than a million times the mass of our sun -– which would make it as much as 100 times smaller than others of its type.

To get their measurement, astronomers used NASA’s Hubble Space Telescope and a technique similar to Doppler radar -- the method that meteorologists use to track weather systems.

The black hole lies 14 million light-years away, in the center of the galaxy NGC 4395. One light-year is the distance light travels in one year -- approximately six trillion miles.

Astronomers consider NGC 4395 to be an “active galaxy,” one with a very bright center, or nucleus. Current theory holds that black holes may literally be consuming active galactic nuclei (AGNs). Black holes in AGNs are supposed to be very massive.

NGC 4395 appears to be special, because the black hole in the center of the galaxy is much smaller than those found in other active galaxies, explained Ari Laor, professor of astronomy at the Technion, in Haifa, Israel, and Brad Peterson, professor of astronomy at Ohio State.

While astronomers have found much evidence of black holes that are larger than a million solar masses or smaller than a few tens of solar masses, they haven’t found as many midsize black holes -- ones on the scale of hundreds or thousands of solar masses.

Black holes such as the one in NGC 4395 provide a step in closing that gap.

Laor and Peterson and their colleagues used the Doppler radar-like technique to track the movement of gas around the center of NGC 4395. Whereas radar bounces a radio frequency signal off of an object, the astronomers observed light signals that naturally emanated from the center of the galaxy, and timed how long those signals took to reach the orbiting gas.

The method is called reverberation mapping, and Peterson’s team is among a small number of groups who are developing it as a reliable means of measuring black hole masses. The method works because gas orbits faster around massive black holes than it does around smaller ones.

Peterson reported the early results Saturday at the meeting of the American Association for the Advancement of Science in Washington, DC.

Two of the team members -- Luis Ho of the Observatories of the Carnegie Institution of Washington, and Alex Fillippenko of the University of California, Berkeley -- were the first to suspect that the black hole mass was very small. Filippenko and Wallace L.W. Sargent of the California Institute of Technology first discovered the black hole in 1989.

This is the first time astronomers have been able to measure the mass of the black hole in NGC 4395, and confirm that it is indeed smaller than others of its kind.

Peterson and Laor emphasized that the results are very preliminary, but the black hole seems to be at least a hundred times smaller than any other black hole ever detected inside an AGN.

The astronomers want to refine that estimate before they address the next most logical question: why is the black hole so small?

“Is it the runt of the litter, or did it just happen to form under special circumstances? We don’t know yet,” Peterson said.

NGC 4395 doesn’t appear to have a dense spherical nucleus, called a galactic bulge, at its center; it could be that the black hole “ate” all the stars in the bulge, and doesn’t have any more food within reach. That would keep the black hole from growing.

Team members are most interested in what the black hole measurement can tell astronomers about AGNs in general. Any new information could help astronomers better understand the role that black holes play in making galaxies like our own form and evolve. To that end, the team is also studying related data from NASA’s Chandra X-ray Observatory and ground-based telescopes.

“It’s these extreme types of objects that really allow you to test your theories,” Peterson said.


Story Source:

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


Cite This Page:

Ohio State University. "Astronomers Measure Mass Of Smallest Black Hole In A Galactic Nucleus." ScienceDaily. ScienceDaily, 2 March 2005. <www.sciencedaily.com/releases/2005/02/050223152854.htm>.
Ohio State University. (2005, March 2). Astronomers Measure Mass Of Smallest Black Hole In A Galactic Nucleus. ScienceDaily. Retrieved January 28, 2015 from www.sciencedaily.com/releases/2005/02/050223152854.htm
Ohio State University. "Astronomers Measure Mass Of Smallest Black Hole In A Galactic Nucleus." ScienceDaily. www.sciencedaily.com/releases/2005/02/050223152854.htm (accessed January 28, 2015).

Share This


More From ScienceDaily



More Space & Time News

Wednesday, January 28, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Asteroid's Moon Spotted During Earth Flyby

Asteroid's Moon Spotted During Earth Flyby

Rumble (Jan. 27, 2015) — Scientists working with NASA&apos;s Deep Space Network antenna at Goldstone, California discovered an unexpected moon while observing asteroid 2004 BL86 during its recent flyby past Earth. Credit to &apos;NASA JPL&apos;. Video provided by Rumble
Powered by NewsLook.com
Water Fleas Prepare for Space Voyage

Water Fleas Prepare for Space Voyage

Reuters - Innovations Video Online (Jan. 26, 2015) — Scientists are preparing a group of water fleas for a unique voyage into space. The aquatic crustaceans, known as Daphnia, can be used as a miniature model for biomedical research, and their reproductive and swimming behaviour will be tested for signs of stress while on board the International Space Station. Jim Drury went to meet the team. Video provided by Reuters
Powered by NewsLook.com
Mars Rover Opportunity Celebrates 11-Year Anniversary

Mars Rover Opportunity Celebrates 11-Year Anniversary

Rumble (Jan. 26, 2015) — Eleven years ago NASA&apos;s Opportunity rover touched down on Mars for what was only supposed to be a 90-day mission. Since then it has traveled 25.9 miles (41.7 kilometers), further than any other off-Earth surface vehicle has ever driven. Credit to &apos;NASA&apos;. Video provided by Rumble
Powered by NewsLook.com
NASA's On Course To Take Pluto's Best Photo Ever

NASA's On Course To Take Pluto's Best Photo Ever

Newsy (Jan. 25, 2015) — NASA&apos;s New Horizons probe is en route to snap a picture of Pluto this summer, but making sure it doesn&apos;t miss its one chance to do so starts now. Video provided by Newsy
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