Featured Research

from universities, journals, and other organizations

Caught in the act: Herschel detects gigantic storms sweeping entire galaxies clean

Date:
May 9, 2011
Source:
Max-Planck-Institut für extraterrestrische Physik (MPE)
Summary:
With observations the Herschel space observatory, scientists have found gigantic storms of molecular gas gusting in the centres of many galaxies. Some of these massive outflows reach velocities of more than 1000 kilometers per second -- thousands of times faster than in terrestrial hurricanes. The observations show that the more active galaxies contain stronger winds, which can blow away the entire gas reservoir in a galaxy, thereby inhibiting both further star formation and the growth of the central black hole. This finding is the first conclusive evidence for the importance of galactic winds in the evolution of galaxies.

This illustration shows an Ultra-Luminous InfraRed Galaxy (ULIRG) that exhibits massive outflows of molecular gas.
Credit: ESA/AOES Medialab

With observations from the PACS instrument on board the ESA Herschel space observatory, an international team of scientists led by the Max Planck Institute for Extraterrestrial Physics has found gigantic storms of molecular gas gusting in the centres of many galaxies.

Related Articles


Some of these massive outflows reach velocities of more than 1000 kilometres per second, i.e. thousands of times faster than in terrestrial hurricanes. The observations show that the more active galaxies contain stronger winds, which can blow away the entire gas reservoir in a galaxy, thereby inhibiting both further star formation and the growth of the central black hole. This finding is the first conclusive evidence for the importance of galactic winds in the evolution of galaxies.

In the distant and therefore younger Universe, many galaxies show much more activity than our Milky Way today. In commonly accepted evolutionary scenarios gas-rich galaxies merge, which triggers increased star formation ("starburst" galaxies) as well as the growth of supermassive black holes at their centres. This increased activity, however, seems to cease fairly suddenly, effectively stalling star formation and further growth of the black hole in as little as a few million years' time. What processes could be responsible for removing all the raw material powering this activity -- around a billion solar masses -- in such a (cosmologically) short timespan?

The solution to this riddle could be powerful winds that blow gas outwards from the centre of the galaxy. Powered by newly formed stars, shocks from stellar explosions or by the Black Hole in the galaxy's centre, these storms would remove all the gas supply from the galaxy thereby halting the same mechanisms that produced them in the first place.

"Outflows are key features in models of galactic formation and evolution, but prior to our work no decisive evidence of their active role in such processes had been gathered," explains Eckhard Sturm from the Max Planck Institute for Extraterrestrial Physics (MPE). Sturm led a study of ultra-luminous infrared galaxies with the PACS instrument on board the Herschel space observatory, which revealed massive outflows of molecular gas. Almost all previous observations dealt mainly with neutral and ionised gas, which does not contribute to the formation of stars.

"By detecting outflows in cold molecular gas from which stars are born, we can finally witness their direct impact on star formation," Sturm adds. "Star formation stalls as the gas supply is blown out of the centres of the galaxies with a rate of up to a thousand solar masses per year."

However, the observations not only reveal an intermediate stage of galaxy evolution, from disc galaxies with many young stars and a large gas fraction to elliptical galaxies with old stellar populations and little gas. In addition, they can explain another empirical property: The mass of the Black Hole in the centre and the mass of stars in the inner regions of a galaxy seem to correlate. Such a correlation is a natural consequence of the newly found galactic outflows as they remove the common gas reservoir thus inhibiting both star formation and the growth of the Black Hole.

"Herschel's sensitivity enabled us to detect these gigantic galactic storms, and to demonstrate, for the first time, that they may be strong enough to shut down stellar production entirely," says co-author Albrecht Poglitsch, also from MPE and the Principal Investigator of PACS.

The sample of galaxies observed is still too small to pin down the driving force behind these outflows. The first results seem to indicate that the galaxies fall in two categories: starburst-dominated objects loose material of up to a few hundred solar masses per year which is similar to their star formation rate; with velocities of a few hundred kilometres per second these outflows are probably driven by radiation pressure from starbursts or supernovae explosions. Galaxies dominated by the activity of the black hole in their centre loose material at much higher rates, up to a thousand solar masses per year or more; with velocities around 1000 kilometres per second these outflows are probably powered mostly by radiation pressure from the active galactic nucleus. To confirm these first conclusions and study potential trends in the outflow characteristics, the Herschel-PACS observations will continue to cover a much larger sample of galaxies.


Story Source:

The above story is based on materials provided by Max-Planck-Institut für extraterrestrische Physik (MPE). Note: Materials may be edited for content and length.


Journal Reference:

  1. E. Sturm, E. González-Alfonso, S. Veilleux, J. Fischer, J. Graciá-Carpio, S. Hailey-Dunsheath, A. Contursi, A. Poglitsch, A. Sternberg, R. Davies, R. Genzel, D. Lutz, L. Tacconi, A. Verma, R. Maiolino, J. A. de Jong. Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS. The Astrophysical Journal, 2011; 733 (1): L16 DOI: 10.1088/2041-8205/733/1/L16

Cite This Page:

Max-Planck-Institut für extraterrestrische Physik (MPE). "Caught in the act: Herschel detects gigantic storms sweeping entire galaxies clean." ScienceDaily. ScienceDaily, 9 May 2011. <www.sciencedaily.com/releases/2011/05/110509091415.htm>.
Max-Planck-Institut für extraterrestrische Physik (MPE). (2011, May 9). Caught in the act: Herschel detects gigantic storms sweeping entire galaxies clean. ScienceDaily. Retrieved January 31, 2015 from www.sciencedaily.com/releases/2011/05/110509091415.htm
Max-Planck-Institut für extraterrestrische Physik (MPE). "Caught in the act: Herschel detects gigantic storms sweeping entire galaxies clean." ScienceDaily. www.sciencedaily.com/releases/2011/05/110509091415.htm (accessed January 31, 2015).

Share This


More From ScienceDaily



More Space & Time News

Saturday, January 31, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Video Shows Stars If They Were as Close to Earth as Sun

Video Shows Stars If They Were as Close to Earth as Sun

Buzz60 (Jan. 30, 2015) — Russia&apos;s space agency created a video that shows what our sky would look like with different star if they were as close as our sun. Patrick Jones (@Patrick_E_Jones) walks us through the cool video. Video provided by Buzz60
Powered by NewsLook.com
Dog-Loving Astronaut Wins Best Photo of 2015

Dog-Loving Astronaut Wins Best Photo of 2015

Buzz60 (Jan. 30, 2015) — Retired astronaut and television host, Leland Melvin, snuck his dogs into the NASA studio so they could be in his official photo. As Mara Montalbano (@maramontalbano) shows us, the secret is out. Video provided by Buzz60
Powered by NewsLook.com
NASA Holds Memorial to Remember Astronauts

NASA Holds Memorial to Remember Astronauts

AP (Jan. 29, 2015) — NASA is remembering 17 astronauts who were killed in the line of duty and dozens more who have died since the agency&apos;s beginning. A remembrance ceremony was held Thursday at NASA&apos;s Marshall Space Flight Center in Alabama. (Jan. 29) Video provided by AP
Powered by NewsLook.com
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

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