Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Research reveals the real cause of death for some starburst galaxies

14.11.2014

Like hedonistic rock stars that live by the “better to burn out than to fade away” credo, certain galaxies flame out in a blaze of glory. Astronomers have struggled to grasp why these young “starburst” galaxies — ones that are very rapidly forming new stars from cold molecular hydrogen gas up to 100 times faster than our own Milky Way — would shut down their prodigious star formation to join a category scientists call “red and dead.”

Starburst galaxies typically result from the merger or close encounter of two separate galaxies. Previous research had revealed spouts of gas shooting outward from such galaxies at up to 2 million miles per hour. But astronomers lacked direct evidence of what expelled the gas, the fundamental ingredient for crafting new stars.


Graphic at right: The 12 galaxies in these Hubble Space Telescope images are undergoing a firestorm of star birth, as shown by their bright white cores. Hubble reveals that the galaxies’ star-making frenzy was ignited by mergers with other galaxies. The odd shapes of many of the galaxies are telltale evidence of those close encounters The new Hubble Wide Field Camera 3 observations suggest that energy from the star-birthing frenzy created powerful winds that are blowing out the gas, squelching future generations of stars. This activity occurred when the universe was half its current age of 13.7 billion years. The gas-poor galaxies may eventually become so-called “red and dead” galaxies, composed only of aging stars. The galaxies are the most compact yet found. They contain as much mass as our Milky Way galaxy, but packed into a much smaller area. The smallest galaxies are about 650 light-years across, 1/60th the width of our Milky Way galaxy. The Hubble false-color images were processed to bring out important details in the galaxies. The images were taken in 2010. Credit: NASA, ESA, and P. Sell (Texas Tech University, Lubbock)

“To form stars you need dense gas,” said Gregory Rudnick, associate professor of physics and astronomy at the University of Kansas. “Most of the gas in the universe is made up of hydrogen and in very dense areas this gas is no longer formed of atoms but rather of molecules of hydrogen. When the gas gets dense enough and isn’t too hot, small portions of that gas can collapse to form stars. Without a lot of cool dense gas, around -420 to -280 degrees Fahrenheit, stars can’t form.”

Now, Rudnick and a team of fellow astronomers have solved the mystery of why compact, young galaxies become galactic ruins. Using NASA’s Hubble Space Telescope and Chandra X-ray Observatory, they found that energy from the star formation itself created a shortage of gas within the starburst galaxies they studied, shutting down the potential for further crafting of stars. The group’s findings were published recently in the Monthly Notices of the Royal Astronomical Society.

“As the stars form, the most massive and hot ones emit enough light that the pressure of this light on the gas can push the gas out of the galaxy,” Rudnick said. “When these stars explode, the energy from these explosions can do the rest of the job and push most of the gas clear of the galaxy. We think we are witnessing such an occurrence.”

Rudnick and his fellow researchers analyzed 12 merging galaxies as the curtain fell on their star making. The team’s observations overturned an earlier idea that supermassive black holes, also known as “active galactic nuclei,” or AGN, were responsible for throwing gas from these starburst galaxies.

“One favored possibility for this was that the gas that fuels star formation was forcibly ejected from the galaxy over about tens of million years,” Rudnick said. “It was suspected that it had something to do with the presence of a supermassive black hole at the center of the galaxy. Just before gas enters a black hole, it can become extremely hot and literally cause a wind that can drive out the gas from the rest of the galaxy.

While a possible cause of the blowout, there had been no direct evidence for this process in driving out the gas in these compact galaxies. Indeed, before our studies no one had ever even observed a compact galaxy exhibiting a strong wind and blowing out its gas.”

The findings suggest the same extreme condiitions that turn compact galaxies into prolific star-making machines also bring on the eventual demise of their star production. In other words, supermassive black holes, or AGN, aren’t to blame.

“There is so much star formation that it’s possible the energy from the star formation itself is able to stop the star formation,” said the KU researcher. “We originally thought these galaxies might have an accreting supermassive black hole that was causing the breakneck winds. This is because the speeds were so high and we had never seen star formation doing this effective of a job before at pushing a strong wind. This work surprisingly shows that supermassive black holes probably aren’t important in causing these outflows. This is important, as many studies of galaxy evolution have shown that these black holes may play a key role in regulating star formation in galaxies. What we’ve shown is these very vigorously star-forming and extremely compact galaxies don’t require a big black hole but can do the job via their star formation alone. Indeed, the star formation may be occurring at the fastest rate possible before shutting itself off. This is a galaxy that is pushing itself towards a shutdown. This will be an important element to include in future revisions of galaxy evolution models.”

The Smithsonian Astrophysical Observatory, NASA, the Space Telescope Science Institute and the Alexander von Humboldt Foundation supported this work.

Top graphic: This illustrates how a vibrant, star-forming galaxy quickly transforms into a sedate galaxy composed of old stars. The scenario begins when two galaxies merge (Panel 1), funneling a large amount of gas into the central region. The gas compresses, sparking a firestorm of star birth, which blows out most of the remaining star-forming gas (Panel 2). Devoid of its fuel, the galaxy settles into a quiet existence, composed of aging stars (Panel 3). Credit: A. Feild (STScI)

The University of Kansas is a major comprehensive research and teaching university. The university's mission is to lift students and society by educating leaders, building healthy communities and making discoveries that change the world. The KU News Service is the central public relations office for the Lawrence campus.

kunews@ku.edu | 1450 Jayhawk Blvd., Suite 37, Lawrence, KS 66045

Brendan M. Lynch | EurekAlert!
Further information:
http://news.ku.edu/research-reveals-real-cause-death-some-starburst-galaxies

More articles from Physics and Astronomy:

nachricht DGIST develops 20 times faster biosensor
24.04.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht New quantum liquid crystals may play role in future of computers
21.04.2017 | California Institute of Technology

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Early organic carbon got deep burial in mantle

25.04.2017 | Earth Sciences

A room with a view - or how cultural differences matter in room size perception

25.04.2017 | Life Sciences

Warm winds: New insight into what weakens Antarctic ice shelves

25.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>