Featured Research

from universities, journals, and other organizations

Which Came First: Black Hole Or Galaxy?

Date:
January 14, 2000
Source:
University Of Michigan
Summary:
U-M astronomer says black holes formed early and influenced galactic evolution.

U-M astronomer says black holes formed early and influenced galactic evolution.

ATLANTA --- A team of astronomers conducting a systematic search for supermassive black holes has discovered three more of the mysterious objects lurking in the centers of nearby elliptical galaxies. This brings the total number of supermassive black holes definitively identified so far to 20. The discovery was announced at a news conference held here Jan. 13 during the American Astronomical Society Meeting.

"The formation and evolution of galaxies are intimately connected to the presence of a central massive black hole," said Douglas Richstone, leader of the research team and a University of Michigan professor of astronomy. "Radiation and high-energy particles released by the formation and growth of black holes are the dominant sources of heat and kinetic energy for star-forming gas in protogalaxies."

Richstone says the team's conclusions are inferred from two pieces of evidence. First, all or nearly all galaxies with spheroidal distributions of stars (bulges in spirals) seem to have massive black holes. The mass of these objects seems to correlate with the mass of the central part of the host galaxy. "The ubiquity of this association, as well as the correlation, points to a connection between the massive black hole and the galaxy, and poses a 'chicken and egg' dilemma of which came first," Richstone said.

Second, comparisons of the history of star formation in the universe with the history of quasars, conducted by other scientists, reveal that quasars developed well before most star formation in galaxies. Quasars are extremely powerful bright objects capable of generating the luminosity of one trillion suns within a region the size of Mars' orbit.

"The massive black holes now seen in centers of galaxies are relics of these quasars," Richstone explained. "So these black holes must have been present at the height of the quasar epoch when the universe was about one billion years old."

To detect the existence of new black holes, Richstone and his colleagues use a computer model to detect abrupt changes in star velocity patterns as stars spiral closer to the galactic center. Input for the computer model comes from Hubble Space Telescope observations and ground-based spectroscopic data obtained at MDM Observatory, which is operated by the University of Michigan, Dartmouth College, Columbia University and Ohio State University. The technique was developed by Karl Gebhardt, a former U-M postdoctoral fellow, who is now affiliated with Lick Observatory at the University of California-Santa Cruz.

"Based on the size of the galaxy and the velocity pattern of stars at the core of the galaxy, we not only can detect the signal from a black hole, we also can estimate its mass," Gebhardt said. "Masses of the three new black holes detected with the model range from 50 million to 100 million suns, which continues our previously reported correlation of black hole mass with galaxy mass."

The team's newest black holes were identified in galaxies NGC 4473 and NGC 4697, located in the constellation Virgo, and NGC 821 in Aries. "Stellar orbital distributions in these three galaxies are characteristic of others studied with our model, suggesting a common history among all galaxies," Gebhardt said.

Other astronomers on the black-hole-census research team include Jason Pinkney, a U-M postdoctoral fellow; John Magorrian, Cambridge University; John Kormendy, University of Hawaii; Tod Lauer, Gary Bower and Richard Green, National Optical Astronomy Observatory (NOAO); Alan Dressler and Luis Ho, Carnegie Observatories; Sandra Faber and Alex Filippenko, University of California; Ralf Bender, Ludwig Maximilian University in Munich; and Scott Tremaine, Princeton University.

Research funding was provided by NASA and the Space Telescope Science Institute.


Story Source:

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


Cite This Page:

University Of Michigan. "Which Came First: Black Hole Or Galaxy?." ScienceDaily. ScienceDaily, 14 January 2000. <www.sciencedaily.com/releases/2000/01/000113103114.htm>.
University Of Michigan. (2000, January 14). Which Came First: Black Hole Or Galaxy?. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2000/01/000113103114.htm
University Of Michigan. "Which Came First: Black Hole Or Galaxy?." ScienceDaily. www.sciencedaily.com/releases/2000/01/000113103114.htm (accessed July 24, 2014).

Share This




More Space & Time News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: ISS Cargo Ship Launches in Kazakhstan

Raw: ISS Cargo Ship Launches in Kazakhstan

AP (July 23, 2014) The Progress 56 cargo ship launched from the Baikonur Cosmodrome in Kazakhstan Wednesday. NASA says it will deliver cargo and crew supplies to the International Space Station. (July 23) Video provided by AP
Powered by NewsLook.com
Raw: Cargo Craft Undocks from Space Station

Raw: Cargo Craft Undocks from Space Station

AP (July 22, 2014) A Russian Soyuz cargo-carrying spacecraft undocked from the International Space Station on Monday. The craft is due to undergo about ten days of engineering tests before it burns up in the Earth's atmosphere. (July 22) Video provided by AP
Powered by NewsLook.com
NASA Ceremony Honors Moon Walker Neil Armstrong

NASA Ceremony Honors Moon Walker Neil Armstrong

AP (July 21, 2014) NASA honored one of its most famous astronauts Monday by renaming a historic building at the Kennedy Space Center in Florida. It now bears the name of Neil Armstrong, the first man to walk on the moon. (July 21) Video provided by AP
Powered by NewsLook.com
Neil Armstrong's Post-Apollo 11 Life

Neil Armstrong's Post-Apollo 11 Life

Newsy (July 19, 2014) Neil Armstrong gained international fame after becoming the first man to walk on the moon in 1969. But what was his life like after the historic trip? 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:
from the past week

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