Nav: Home

Galaxy murder mystery

January 16, 2017

It's the big astrophysical whodunnit. Across the Universe, galaxies are being killed and the question scientists want answered is, what's killing them?

New research published today by a global team of researchers, based at the International Centre for Radio Astronomy Research (ICRAR), seeks to answer that question. The study reveals that a phenomenon called ram-pressure stripping is more prevalent than previously thought, driving gas from galaxies and sending them to an early death by depriving them of the material to make new stars.

The study of 11,000 galaxies shows their gas--the lifeblood for star formation--is being violently stripped away on a widespread scale throughout the local Universe.

Toby Brown, leader of the study and PhD candidate at ICRAR and Swinburne University of Technology, said the image we paint as astronomers is that galaxies are embedded in clouds of dark matter that we call dark matter halos.

Dark matter is the mysterious material that despite being invisible accounts for roughly 27 per cent of our Universe, while ordinary matter makes up just 5 per cent. The remaining 68 per cent is dark energy.

"During their lifetimes, galaxies can inhabit halos of different sizes, ranging from masses typical of our own Milky Way to halos thousands of times more massive," Mr Brown said.

"As galaxies fall through these larger halos, the superheated intergalactic plasma between them removes their gas in a fast-acting process called ram-pressure stripping.

"You can think of it like a giant cosmic broom that comes through and physically sweeps the gas from the galaxies."

Mr Brown said removing the gas from galaxies leaves them unable to form new stars.

"It dictates the life of the galaxy because the existing stars will cool off and grow old," he said.

"If you remove the fuel for star formation then you effectively kill the galaxy and turn it into a dead object."

ICRAR researcher Dr Barbara Catinella, co-author of the study, said astronomers already knew ram-pressure stripping affected galaxies in clusters, which are the most massive halos found in the Universe.

"This paper demonstrates that the same process is operating in much smaller groups of just a few galaxies together with much less dark matter," said Mr Brown.

"Most galaxies in the Universe live in these groups of between two and a hundred galaxies," he said.

"We've found this removal of gas by stripping is potentially the dominant way galaxies are quenched by their surrounds, meaning their gas is removed and star formation shuts down."

The study was published in the journal Monthly Notices of the Royal Astronomical Society.

It used an innovative technique combining the largest optical galaxy survey ever completed--the Sloan Digital Sky Survey--with the largest set of radio observations for atomic gas in galaxies --the Arecibo Legacy Fast ALFA survey.

Mr Brown said the other main process by which galaxies run out of gas and die is known as strangulation.

"Strangulation occurs when the gas is consumed to make stars faster than it's being replenished, so the galaxy starves to death," he said.

"It's a slow-acting process. On the contrary, what ram-pressure stripping does is bop the galaxy on the head and remove its gas very quickly--of the order of tens of millions of years--and astronomically speaking that's very fast."
-end-
Original Publication: 'Cold gas stripping in satellite galaxies: from pairs to clusters', published in the Monthly Notices of the Royal Astronomical Society on January 17th, 2017. Available from http://www.icrar.org/galaxy-murder-mystery (embargo period password is 'darkenergy')

More Information: The International Centre for Radio Astronomy Research (ICRAR) is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.

Multimedia: An animation and high-resolution images are available from http://www.icrar.org/galaxy-murder-mystery (Embargo period password is 'darkenergy')

Contacts: Mr Toby Brown (ICRAR-UWA, Swinburne University of Technology)
Ph: +61 08 6488 7753 E: toby.brown@icrar.org
Dr Barbara Catinella (ICRAR-UWA)
Ph: +61 08 6488 7760 E: barbara.catinella@icrar.org
Pete Wheeler (Media Contact, ICRAR)
Ph: +61 423 982 018 E: pete.wheeler@icrar.org

International Centre for Radio Astronomy Research

Related Dark Matter Articles:

Does dark matter annihilate quicker in the Milky Way?
Researchers at the Tata Institute of Fundamental Research in Mumbai have proposed a theory that predicts how dark matter may be annihilating much more rapidly in the Milky Way, than in smaller or larger galaxies and the early Universe.
Origin of Milky Way's hypothetical dark matter signal may not be so dark
A mysterious gamma-ray glow at the center of the Milky Way is most likely caused by pulsars.
A new look at the nature of dark matter
A new study suggests that the gravitational waves detected by the LIGO experiment must have come from black holes generated during the collapse of stars, and not in the earliest phases of the Universe.
Dark matter may be smoother than expected
Analysis of a giant new galaxy survey, made with ESO's VLT Survey Telescope in Chile, suggests that dark matter may be less dense and more smoothly distributed throughout space than previously thought.
Supercomputer comes up with a profile of dark matter
In the search for the mysterious dark matter, physicists have used elaborate computer calculations to come up with an outline of the particles of this unknown form of matter.
Mapping the 'dark matter' of human DNA
Researchers from ERIBA, Radboud UMC, XJTU, Saarland University, CWI and UMC Utrecht have made a big step towards a better understanding of the human genome.
Reconciling dwarf galaxies with dark matter
Dwarf galaxies are enigmas wrapped in riddles. Although they are the smallest galaxies, they represent some of the biggest mysteries about our universe.
Did gravitational wave detector find dark matter?
When an astronomical observatory detected two black holes colliding in deep space, scientists celebrated confirmation of Einstein's prediction of gravitational waves.
Dark matter does not contain certain axion-like particles
Researchers at Stockholm University are getting closer to corner light dark-matter particle models.
SDU researchers present a new model for what dark matter might be
There are indications that we might never see the universe's mysterious dark matter.

Related Dark Matter Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".