Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Slow motion mergers in galaxy clusters provide conditions to transform spirals to smooth disks

05.04.2006


Astronomers at Liverpool John Moores University may have solved the mystery of how spiral galaxies in clusters are transformed over time into smooth disks. Results from a study of galaxy clusters confirms that the slow-motion conditions needed for the transformation are occurring among populations of galaxies falling towards the cluster centre.



Over the past several billion years the predominant shape of disc galaxies in clusters has changed from a spiral to a smooth disk. Theory suggests that this change occurs when two galaxies of unequal mass merge and gravitational effects pull gas to the galaxies nucleus, sweeping away the spiral structure and leaving behind a smooth, barren, thickened disk known as a lenticular galaxy. However, galaxies orbiting in clusters move at high speeds and in random directions, which should mean that conditions needed for these slow interactions rarely occur. Instead, multiple rapid encounters between galaxies, known as ’galaxy harassment’, are dominant but these types of fast encounters cannot easily form the smooth disks.

The group from Liverpool John Moores compared eight examples of populations of galaxies falling towards the centres of galaxy clusters with control samples of galaxies far from the clusters. They found that the infalling galaxies in the cluster were predominantly distorted in shape and had a higher than normal rates of star formation. Between a half and three-quarters of these galaxies were very close by to another galaxy or appeared to be merging with a companion galaxy, which suggested that interactions and mergers are more common in galaxies falling into the cluster than in the control sample.


"Our findings are very exciting because these results suggest that galaxies are more likely to merge when falling into a cluster and this may explain why clusters today have so few spirals and so many lenticular galaxies" said Dr Chris Moss, who will be presenting the results at the Royal Astronomical Society’s National Astronomy Meeting on the 5th April.

The results suggest the conditions needed for slow galaxy interactions and mergers are more likely to occur in galaxies falling into a galaxy cluster compared to the general population of galaxies outside clusters.

Since infalling of galaxies into clusters was greater in the past, such interactions and mergers may have contributed significantly to the transformation of the past population of cluster spirals to lenticular galaxies in present-day clusters.

The observations were carried out over the past several years using the JKT (Jacobus Kapteyn Telescope) and the Nordic Optical telescope, La Palma based on earlier survey work using the Burrell Schmidt Telescope, Kitt Peak National Observatory.

Anita Heward | alfa
Further information:
http://www.astro.livjm.ac.uk/press/chrismoss.html
http://www.ras.org.uk

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>