Giant filament structures give a rare insight into galaxy cluster evolution

Apr 05, 2006
The RGB image of the BIG group
The RGB image of the BIG group. Blue is Halpha Net band, Red is r' band and Green is Halpha on band.

A new image of the centre of a cluster of galaxies has revealed massive filamentary structures that give a rare insight into the evolution of galaxy clusters.

“The star forming regions in the cluster that we’d observed previously were just the tip of the iceberg. We’ve now observed filaments of gas streaming out from these regions that are approximately 490 thousand light years across. The gaseous trails mark the path of galaxies travelling at high speed through the cluster.

The origin of these unique features is still a matter for debate, but we think the combined action of tidal forces among galaxies in the cluster and of ram-pressure by the ambient medium caused the galaxies to fragment and blast out the ionized gas,” said Dr Luca Cortese, who is presenting the results at the Royal Astronomical Society’s National Astronomy Meeting on 5th April.

An international team, lead by Dr Cortese, studied the physical properties of a compact group that is falling towards the centre of a cluster of galaxies known as Abell1367 at a rate of 1700 km/s. The group, which was discovered in 2002, has the highest density of star forming objects ever observed in local clusters. It contains two giant galaxies, at least ten dwarf galaxies or extragalactic clouds of gas and over a billion solar masses of diffuse gas filaments.

Scientists believe that clusters of galaxies are formed from the accretion of compact groups like the one observed in Abell1367. Formation of clusters of galaxies peaked 5 billion years ago. Now the rate is at least three times lower and it will slow dramatically due to the effects of the acceleration of the Universe. The Abell1367 group is particularly important as it is only 300 million light years from Earth – ‘local’ in terms of the Universe – and so the scientists can see the processes at work in unprecedented detail. Dr Cortese explains, “The physical processes seen here are typical of young clusters, found far away in space and a long time ago. To really understand what’s going on, we need a close up view. This is the first time we have found an example of a galaxy group mid-way through its transformation that is close enough for us to have a really good look at the structures surrounding the galaxies.”

The results suggest that at least part of the changes to the structure of cluster galaxies that took place in earlier epochs happened very differently to ones observed in today’s clusters. In today’s clusters of galaxies, the galaxies are travelling faster than in the infalling groups, which means that gravitational interactions between galaxies happen much faster.

The study was carried out using the Italian National Telescope Galileo in La Palma in April 2004 and February 2006.

The results of this study are accepted for publication on Astronomy and Astrophysics.

Source: Royal Astronomical Society

Explore further: Lockheed Martin successfully mates NOAA GOES-R satellite modules

add to favorites email to friend print save as pdf

Related Stories

Astronomers unveil secrets of giant elliptical galaxies

Sep 12, 2014

New findings of how giant elliptical galaxies move have been discovered by an international team of astronomers using the newly installed Multi Unit Spectroscopic Explorer (MUSE) at the European Southern Observatory's (ESO) ...

This star cluster is not what it seems

Sep 10, 2014

This new image from the VLT Survey Telescope in northern Chile shows a vast collection of stars, the globular cluster Messier 54. This cluster looks similar to many others but it has a secret. Messier 54 ...

Three comets for northern hemisphere observers

Sep 10, 2014

As the Chinese proverb says, "May you live in interesting times," and while the promise of Comet ISON dazzling observers didn't exactly pan out as hoped for in early 2014, we now have a bevy of binocular ...

Image: Hubble sees spiral in Serpens

Sep 08, 2014

( —This new NASA/ESA Hubble Space Telescope image shows a beautiful spiral galaxy known as PGC 54493, located in the constellation of Serpens (The Serpent). This galaxy is part of a galaxy cluster ...

Cosmologists probe beyond the Big Bang

Sep 05, 2014

A long tradition of cosmology research in Cornell's College of Arts and Sciences has given birth to a vigorous effort by a new generation of cosmologists to understand the Cosmic Microwave Background (CMB), the thermal radiation ...

Cosmic forecast: Dark clouds will give way to sunshine

Sep 03, 2014

Lupus 4, a spider-shaped blob of gas and dust, blots out background stars like a dark cloud on a moonless night in this intriguing new image. Although gloomy for now, dense pockets of material within clouds ...

Recommended for you

The Great Cold Spot in the cosmic microwave background

19 hours ago

The cosmic microwave background (CMB) is the thermal afterglow of the primordial fireball we call the big bang. One of the striking features of the CMB is how remarkably uniform it is. Still, there are some ...

Winter in the southern uplands of Mars

19 hours ago

Over billions of years, the southern uplands of Mars have been pockmarked by numerous impact features, which are often so closely packed that they overlap. One such feature is Hooke crater, shown in this ...

Five facts about NASA's ISS-RapidScat

19 hours ago

NASA's ISS-RapidScat mission will observe ocean wind speed and direction over most of the globe, bringing a new eye on tropical storms, hurricanes and typhoons. Here are five fast facts about the mission.

User comments : 0