Featured Research

from universities, journals, and other organizations

Ancient galaxy cluster still producing stars

Date:
August 23, 2010
Source:
Texas A&M University
Summary:
In ongoing observations of one of the universe's earliest, most distant cluster of galaxies using NASA's Spitzer Space Telescope, astronomers have discovered that a significant fraction of those ancient galaxies are still actively forming stars.

Star formation in the Galaxy Cluster CIG J02182-05102.
Credit: Spitzer Space Telescope, IRAC, MIPS/Subaru/NASA/JPL-Caltech/K Tran & C. Papovich (Texas A&M University)

Much like quiet, middle-aged baby boomers peacefully residing in some of the world's largest cities, families of some galaxies also have a hidden wild youth that they only now are revealing for the first time, according to research by astronomers at Texas A&M University.

In ongoing observations of one of the universe's earliest, most distant cluster of galaxies using NASA's Spitzer Space Telescope, an international team of researchers led by Texas A&M's Dr. Kim-Vy Tran has discovered that a significant fraction of those ancient galaxies are still actively forming stars.

Tran, an assistant professor in the Texas A&M Department of Physics and Astronomy and member of the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and her team have spent the past four months analyzing images taken from the Multiband Imaging Photometer for Spitzer (MIPS), essentially looking back in time nearly 10 billion years at a high red-shift cluster known as CLG J02182-05102. Mere months after first discovering the cluster and the fact that it is shockingly "modern" in its appearance and size despite being observed just 4 billion years after the Big Bang, the Texas A&M-led team was able to determine that the galaxy cluster produces hundreds to thousands of new stars every year -- a far higher birthrate than what is present in nearby galaxies.

What is particularly striking, according to Tran, is the fact that the stellar birthrate is higher in the cluster's center than at the cluster's edges -- the exact opposite of what happens in our local portion of the universe, where the cores of galaxy clusters are known to be galactic graveyards full of massive elliptical galaxies composed of old stars.

"A well-established hallmark of galaxy evolution in action is how the fraction of star-forming galaxies decreases with increasing galaxy density," explains Tran, lead author of the team's study which appears in The Astrophysical Journal Letters. "In other words, there are more star-forming galaxies in the field than in the crowded cores of galaxy clusters. However, in our cluster, we find many galaxies with star-formation rates comparable to their cousins in the lower-density field environment."

Exactly why this star power increases as galaxies become more crowded remains a mystery. Tran thinks the densely-populated surroundings could lead to galaxies triggering activity in one another, or that all galaxies were extremely active when the universe was young.

The group's discovery holds potentially compelling implications that could ultimately reveal more about how such massive galaxies form. Observations of nearby galaxy clusters confirm that they are made of stars that are at least 8 to 10 billion years old, which means that CLG J02182-05102 is nearing the end of its hyperactive star-building period.

Now that they have pinpointed the epoch when galaxy clusters are making the last of their stars, astronomers can focus on understanding why massive assemblies of galaxies transition from very active to passive. Identifying how long it takes for galaxies in clusters to build up their stellar mass as well as the time at which they stop provides strong constraints for how these massive galaxies form.

"Our study shows that by looking farther into the distant universe, we have revealed the missing link between the active galaxies and the quiescent behemoths that live in the local universe," Tran adds. "Our discovery indicates that future studies of galaxy clusters in this red-shift range should be particularly fruitful for understanding how these massive galaxies form as a function of their environment."

Tran's team includes fellow Texas A&M astronomer Dr. Casey Papovich, who first identified the galaxy cluster CLG J02182-05102 in May. The collection of roughly 60 galaxies is observed just 4 billion years after the Big Bang, making it the earliest cluster of galaxies ever detected. However, the team was struck not by its age, but by its astoundingly modern appearance -- a huge, red collection of galaxies typical in only local clusters.

The fact that Tran's team was able to see these active galaxies so far back in time (Tran likens their find to discovering that her mild-mannered grandparent had lived a fast and furious youth) is only the preface to what they expect eventually to learn about these clusters. Tran will continue to lead an international collaboration with Papovich and their postdoctoral researchers to examine these clusters more thoroughly and hopefully to understand why they are still so energetic.

"We will analyze new observations scheduled to be taken with the Hubble Space Telescope and Herschel Space Telescope to study these galaxies more carefully to understand why they are so active," Tran adds. "We will also start looking at several more distant galaxy clusters to see if we find similar behavior."


Story Source:

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


Journal Reference:

  1. Tran et al. Reversal of Fortune: Confirmation of an Increasing Star Formation-Density Relation in a Cluster at z=1.62. The Astrophysical Journal, 2010; 719 (2): L126 DOI: 10.1088/2041-8205/719/2/L126

Cite This Page:

Texas A&M University. "Ancient galaxy cluster still producing stars." ScienceDaily. ScienceDaily, 23 August 2010. <www.sciencedaily.com/releases/2010/08/100818141549.htm>.
Texas A&M University. (2010, August 23). Ancient galaxy cluster still producing stars. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2010/08/100818141549.htm
Texas A&M University. "Ancient galaxy cluster still producing stars." ScienceDaily. www.sciencedaily.com/releases/2010/08/100818141549.htm (accessed April 18, 2014).

Share This



More Space & Time News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Space X Launches to Space Station

Raw: Space X Launches to Space Station

AP (Apr. 18, 2014) On it's second attempt this week, The Space X company launched Friday from Cape Canaveral to ferry supplies to the International Space Station. (April 18) Video provided by AP
Powered by NewsLook.com
Unmanned Falcon 9 Rocket Blasts Off from Cape Canaveral Air Force Station in Florida

Unmanned Falcon 9 Rocket Blasts Off from Cape Canaveral Air Force Station in Florida

Reuters - US Online Video (Apr. 18, 2014) The rocket, built and operated by Space Exploration Technologies, carries a Dragon cargo ship loaded with supplies and equipment destined for the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Earth's Near-Twin Found Orbiting Red Dwarf

Earth's Near-Twin Found Orbiting Red Dwarf

Newsy (Apr. 17, 2014) The newly-discovered planet is roughly the size of Earth and could have liquid water on its surface. Video provided by Newsy
Powered by NewsLook.com
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

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