Galactic clusters low on hydrogen

November 25, 2013

Astronomers at Swinburne University of Technology and their international collaborators have found evidence that galaxies that are located in groups might be running out of gas.

Galaxies like our own Milky Way possess large reservoirs of , which is the fuel out of which new stars are formed. Accurate measurements of the gas content, in addition to the stellar properties, are critical in predicting how a galaxy will evolve.

Taking advantage of the sensitivity of the Arecibo telescope, the largest radio telescope in the world, the research team measured the hydrogen content of a large number of located in different environments, from isolated systems to large groups. These new observations showed that galaxies in groups have, on average, less gas and star formation than similar systems found in isolation.

"What drives the gas in and out of galaxies is one of the most outstanding open questions in extragalactic astronomy," lead researcher Dr Barbara Catinella, an Australian Research Council Future Fellow at Swinburne's Centre for Astrophysics and Supercomputing (CAS), said.

Astronomers have known for decades that spiral galaxies located in clusters have less gas and star formation than similar, isolated galaxies. Clusters are much larger density concentrations, containing several hundred or even thousands of galaxies immersed in the so-called .

"When a galaxy moves through this hot medium, most of its hydrogen gas can be easily removed," Dr Luca Cortese, co-author of the new study and a postdoctoral fellow at CAS, said.

"We know that gas is removed from galaxies that are located in the harsh cluster environment, but this is the first time that we witness similar effects in the more friendly groups."

Dr Catinella said this was an exciting result, which opened up more questions than it solved.

"It is unclear which physical process is responsible for the observed gas deficit in group galaxies. The milder intergalactic medium in groups might not suffice," she said.

Although observations of stars in galaxies do indicate that is less efficient in groups (and more so in clusters), a clear link with the gas hadn't been established until now.

"The observed decrease of gas content in the group environment would naturally explain why those galaxies are less efficient at forming stars," Dr Catinella said. "They are simply running out of fuel."

Future surveys of the gas content of galaxies, such as those planned for the Australian SKA Pathfinder, will help astronomers to better characterise the still largely unknown group environment, and will shed light on the physical processes that drive the evolution of galaxies in the local Universe.

Explore further: Galaxies are running out of gas: study

More information: The GALEX Arecibo SDSS Survey - VIII. Final data release. The effect of group environment on the gas content of massive galaxies,

Related Stories

NASA Hubble sees sparring antennae galaxies

November 18, 2013

The NASA/ESA Hubble Space Telescope has snapped the best ever image of the Antennae Galaxies. Hubble has released images of these stunning galaxies twice before, once using observations from its Wide Field and Planetary Camera ...

Image: Hot gas sloshing in a galactic cauldron

November 19, 2013

( —Galaxies are social beasts that are mostly found in groups or clusters – large assemblies of galaxies that are permeated by even larger amounts of diffuse gas. With temperatures of 10 million degrees or more, ...

Infant galaxies merging near 'cosmic dawn'

November 21, 2013

Astronomers using the combined power of the Atacama Large Millimeter/submillimeter Array (ALMA) telescope and NASA's Hubble Space Telescope have discovered a far-flung trio of primitive galaxies nestled inside an enormous ...

Recommended for you

NASA selects investigations for future key planetary mission

October 1, 2015

NASA has selected five science investigations for refinement during the next year as a first step in choosing one or two missions for flight opportunities as early as 2020. Three of those chosen have ties to NASA's Jet Propulsion ...

Dawn team shares new maps and insights about Ceres

October 1, 2015

Mysteries and insights about Ceres are being discussed this week at the European Planetary Science Conference in Nantes, France. NASA's Dawn spacecraft is providing scientists with tantalizing views and other data about the ...


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.