Galaxies on cosmic highways likely to form new stars

London, Jan 30 : New observations from the Spitzer Space Telescope have revealed that galaxies on their way to densely populated galaxy clusters on cosmic filaments, are likely to form new stars.

According to a report in New Scientist, galaxies in relatively empty regions of the universe flock towards densely populated galaxy clusters, attracted there by the clusters' gravity.

The galaxies tend to move along cosmic highways called filaments, which are concentrations of gas and invisible material called dark matter.

Because galaxy clusters are so densely packed, galaxies that live inside have more opportunities to brush up against one another, sometimes triggering star formation.

Earlier, astronomers thought this would make galaxy clusters the most fertile places for stars to form.

But in the 1990s, theoretical studies suggested that filaments might be even more fertile, because the encounters there happen at lower speeds. That means the galaxies spend more time lingering near each other, providing more time in each encounter for galaxies to gravitationally disrupt one another and trigger star birth.

Now, this idea has been bolstered by data from the Spitzer Space Telescope, which can pick out so-called starburst galaxies by their characteristic brightness at a wavelength of 24 microns.

It showed that there is a higher proportion of starburst galaxies along the filaments leading into a galaxy cluster called Abell 1763 than in the cluster itself.

"Our observations show that the fraction of starburst galaxies in the filaments is more than double the number of starburst galaxies inside the cluster region," said Dario Fadda of the Caltech in Pasadena, US, who led a team that used Spitzer to observe the area around the cluster, which is 42 million light years from Earth.

"The new Spitzer findings will provide valuable insights into how galaxies grow and change as they leave cosmic suburbia for the big cities," he added.

According to John Hibbard of the National Radio Astronomy Observatory in Charlottesville, Virginia, US, "Our own Milky Way galaxy is still outside of any galaxy clusters and may go through a starburst episode in about 3 billion years when it merges with the nearby Andromeda galaxy."

ANI