Survey Reveals Building Block Process For Biggest Galaxies

April 12, 2006

A new study of the universe's most massive galaxy clusters shows how mergers play a critical role in their evolution. Astronomers used the twin Gemini Observatory instruments in Hawaii and Chile, and the Hubble Space Telescope to study populations of stars in the universe's most massive galaxy clusters over a range of epochs - the earliest being nearly 7 billion years old, or half the age of the universe.

The team used the Hubble images to map the light distribution of the galaxies in the cluster. Data from the Gemini Multi-Object Spectrograph allowed the team to analyze the light from galaxies to determine their masses, ages and chemical compositions.

"We still don't have a clear picture of how galaxies develop over the history of the Universe, said team leader Jordi Barr of Oxford University. "The strength of this study is that we are able to look at galaxy clusters over a range of epochs."

Barr presented some of the first results of the Gemini/HST Galaxy Cluster Project at a meeting of the Royal Astronomical.

Galaxy clusters contain the most massive galaxies in the universe, but until recently astronomers thought all galaxies in the centers of clusters formed rapidly and then aged without any further changes to their structure in a process known as passive evolution. Results from the Gemini/HST Galaxy Cluster Project show this cannot be the case.

"When we're looking at the most distant galaxy clusters, we are looking back in time to clusters that are in early stages of their formation," Barr said. "The young galaxies in distant clusters appear to be very different from those in the mature clusters that we see in the local Universe."

Barr said his team discovered that the earliest galaxy clusters display a huge variation in their abundances of elements such as oxygen and magnesium, while the chemistry of galaxies in the sample of closer clusters appears to be much more homogenous.

"This difference in chemistry proves that the clusters must actively change over time," Barr said. "If the galaxies in the old clusters have acquired a complete set of elements, it's most likely that they have formed from the mergers of several young galaxies."

The team found star formation is most dependent on galactic mass, and in lower-mass galaxies star formation continues longer. The most massive galaxies in clusters appear to have formed all their stars by the time the universe is just over 1 billion years old, while lower-mass galaxies finish forming their stars some 4 billion years later.

"We see the effects of star-formation in low-mass galaxies, but are unsure about why it's happening," Barr said. "It's possible that star-formation can be shut down very rapidly in dense environments and that the lower-mass galaxies are recent arrivals that are forming stars over a longer period outside the cluster, then falling in - but we are still speculating."

The observations of merging galaxy clusters showed a large proportion of the galaxies in those clusters have undergone recent bursts of star formation. This indicates star formation may be triggered if galaxies are thrown, during the course of a merger, into contact with the gaseous medium pervading the cluster.

The team plans more observations at X-ray wavelengths to study the interactions between galaxies and the distribution and temperature of the surrounding gas.

Copyright 2006 by Space Daily, Distributed United Press International

Explore further: Image: X-ray sources in XMM-Newton's second slew catalogue

Related Stories

Jellyfish-shaped galaxy found in Abell 2670 cluster

April 24, 2017

(Phys.org)—Using the Multi Unit Spectroscopic Explorer (MUSE), astronomers have identified a new elliptical jellyfish-like galaxy in the Abell 2670 cluster. The newly detected galaxy showcases spectacular one-sided tails ...

A lot of galaxies need guarding in this NASA Hubble view

May 4, 2017

Much like the eclectic group of space rebels in the upcoming film Guardians of the Galaxy Vol. 2, NASA's Hubble Space Telescope has some amazing superpowers, specifically when it comes to observing innumerable galaxies flung ...

Is dark matter 'fuzzy'?

April 28, 2017

Astronomers have used data from NASA's Chandra X-ray Observatory to study the properties of dark matter, the mysterious, invisible substance that makes up a majority of matter in the universe. The study, which involves 13 ...

Recommended for you

A new tool for discovering nanoporous materials

May 23, 2017

Materials classified as "nanoporous" have structures (or "frameworks") with pores up to 100 nm in diameter. These include diverse materials used in different fields from gas separation, catalysis, and even medicine (e.g. ...

AI wins as Google algorithm beats No. 1 Go player (Update)

May 23, 2017

Google's computer algorithm AlphaGo narrowly beat the world's top-ranked player in the ancient Chinese board game of Go on Tuesday, reaffirming the arrival of what its developers tout as a ground-breaking new form of artificial ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

JukriS
1 / 5 (1) Jul 12, 2009
Galaxies are huge particles who move in space who dont expanding.

All galaxies energy moving very fast before our stuff and time born.

Today galaxies move almost same direction, but young Universe time, galaxies moving more other direction.

All visible Universe galaxies move far away from one point, who is far away outside visible Universe.

One moment all visible Universe energy move out this space where we are now and next moment out that space where we just moved etc.

Nucleus of atoms expanding/exploding all a time and emit/radiate waves of energy who have a nature of electrons and particle who also expanding/exploding and emit/radiate waves of energy etc......

http://www.onesim....com/296

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.