Featured Research

from universities, journals, and other organizations

Astronomers discover that galaxies are either asleep or awake

Date:
June 22, 2011
Source:
Yale University
Summary:
Astronomers have probed into the distant universe and discovered that galaxies display one of two distinct behaviors: they are either awake or asleep, actively forming stars or are not forming any new stars at all. A new survey shows that even very young galaxies as far away as 12 billion light years display one of these two states, meaning galaxies have behaved this way for more than 85 percent of the history of the universe.

Bluer galaxies are actively "awake" and forming stars, while redder galaxies have shut down and are "asleep."
Credit: NASA, ESA, S. Beckwith (STScI) and the HUDF team

Astronomers have probed into the distant universe and discovered that galaxies display one of two distinct behaviors: they are either awake or asleep, actively forming stars or are not forming any new stars at all.

Scientists have known for several years that galaxies in the nearby universe seem to fall into one of these two states. But a new survey of the distant universe shows that even very young galaxies as far away as 12 billion light years are either awake or asleep as well, meaning galaxies have behaved this way for more than 85 percent of the history of the universe. (Looking at galaxies farther away is like looking back in time when they were much younger, because of how long it takes the light they emit to reach us here on Earth.)

"The fact that we see such young galaxies in the distant universe that have already shut off is remarkable," said Kate Whitaker, a Yale University graduate student and lead author of the paper, which is published in the June 20 online edition of the Astrophysical Journal.

In order to determine whether the galaxies were asleep or awake, Whitaker and her colleagues fabricated a new set of filters, each one sensitive to different wavelengths of light, which they used on a 4-meter Kitt Peak telescope in Arizona. They spent 75 nights peering into the distant universe and collecting light from 40,000 galaxies ranging in distance from the nearby universe out to 12 billion light years away. The resulting survey is the deepest and most complete ever made at those distances and wavelengths of light.

The team deciphered the galaxies' dual behavior based on the color of the light they emit. Because of the physics of star formation, active, wakeful galaxies appear bluer, while the light emitted by passive, sleepy galaxies tends toward the redder end of the spectrum.

The researchers found that there are many more active galaxies than passive ones, which agrees with the current thinking that galaxies start out actively forming stars before eventually shutting down.

"We don't see many galaxies in the in-between state," said Pieter van Dokkum, a Yale astronomer and another author of the paper. "This discovery shows how quickly galaxies go from one state to the other, from actively forming stars to shutting off."

Whether the sleeping galaxies have completely shut down remains an open question, Whitaker said. However, the new study suggests the active galaxies are forming stars at rates about 50 times greater than their sleepy counterparts.

"Next, we hope to determine whether galaxies go back and forth between waking and sleeping or whether they fall asleep and never wake up again," van Dokkum said. "We're also interested in how long it takes galaxies to fall asleep, and whether we can catch one in the act of dozing off."

Other authors of the study include Ivo Labbι (Leiden University and Carnegie Observatories); Gabriel Brammer (Yale University and European Southern Observatory); Mariska Kriek (Princeton University and Harvard-Smithsonian Center for Astrophysics); Danilo Marchesini (Tufts University); Ryan Quadri and Marijn Franx (Leiden University); Adam Muzzin, Rachel Bezanson, Kyoung-Soo Lee, Britt Lundgren, Erica Nelson, Tomer Tal and David Wake (Yale University); Rik Williams (Carnegie Observatories); Garth Illingworth (UCO/Lick Observatory); and Gregory Rudnick (University of Kansas).


Story Source:

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


Journal Reference:

  1. Katherine E. Whitaker, Ivo Labbe, Pieter G. van Dokkum, Gabriel Brammer, Mariska Kriek, Danilo Marchesini, Ryan F. Quadri, Marijn Franx, Adam Muzzin, Rik J. Williams, Rachel Bezanson, Garth D. Illingworth, Kyoung-Soo Lee, Britt Lundgren, Erica J. Nelson, Gregory Rudnick, Tomer Tal, David A. Wake. The NEWFIRM Medium-band Survey: Photometric Catalogs, Redshifts and the Bimodal Color Distribution of Galaxies out to z~3. The Astrophysical Journal, 2011

Cite This Page:

Yale University. "Astronomers discover that galaxies are either asleep or awake." ScienceDaily. ScienceDaily, 22 June 2011. <www.sciencedaily.com/releases/2011/06/110621101135.htm>.
Yale University. (2011, June 22). Astronomers discover that galaxies are either asleep or awake. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2011/06/110621101135.htm
Yale University. "Astronomers discover that galaxies are either asleep or awake." ScienceDaily. www.sciencedaily.com/releases/2011/06/110621101135.htm (accessed April 17, 2014).

Share This



More Space & Time News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Baby Moon 'Peggy' Spotted In Saturn's Rings

New Baby Moon 'Peggy' Spotted In Saturn's Rings

Newsy (Apr. 15, 2014) — A bump in the rings could be a half-mile-wide miniature moon. It was found by accident in Cassini probe images. Video provided by Newsy
Powered by NewsLook.com
Americas Glimpse Total Lunar Eclipse

Americas Glimpse Total Lunar Eclipse

AFP (Apr. 15, 2014) — A total lunar eclipse, the first since December 2011, took place early Tuesday morning with the Americas getting the best glimpse. Duration: 1:19 Video provided by AFP
Powered by NewsLook.com
NASA Showcases Lunar Eclipse

NASA Showcases Lunar Eclipse

AP (Apr. 15, 2014) — Star gazers in parts of North and South America got a rare treat early Tuesday morning - a total eclipse of the moon. (April 15) Video provided by AP
Powered by NewsLook.com
Spacecrafts Could Use Urine As Fuel Source

Spacecrafts Could Use Urine As Fuel Source

Newsy (Apr. 15, 2014) — New research says the urea from urine could be recycled for fuel. Urea is filtered out of wastewater when making drinking water. 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