SAMI Galaxy Survey boosted to dissect thousands of galaxies

The equivalent of $3 million in observing time using Australia’s premier optical telescope have been awarded to an Australian and international research team, led by the University of Sydney and CAASTRO.

The team, headed by USyd academic and CAASTRO Chief Investigator Associate Professor Scott Croom, will have at least 150 nights over the next three years to target more than 3,000 galaxies with an innovative new instrument, the Sydney-AAO Multi-object Integral field spectrograph (SAMI).

The project was selected in a competitive process for next generation surveys on the Anglo-Australian Telescope near Coonabarabran in central New South Wales.

SAMI uses new photonic technology to take spatially resolved spectroscopic data for a dozen galaxies at once, allowing surveys to be an order of magnitude larger than before.

“Galaxies are intrinsically complex systems with billions of stars, gas and dust, as well as super-massive black holes and dark matter - and all interact with each other”, said Professor Croom.

Capturing this complexity observationally and discerning the underlying physical processes is an incredibly difficult task.

Previous surveys have observed galaxies using either a single optical fibre per galaxy (for many galaxies at once) or spatially resolved spectroscopy (for one galaxy at a time), but SAMI now merges these two approaches to collect spatially resolved data for many galaxies at once.

“Looking at a galaxy with a single fibre is like trying to understand a city like Sydney by just studying the CBD,” said Professor Croom “With SAMI we can map entire galaxies, including the galactic suburbs.”

SAMI enables astronomers to slice-and-dice galaxies like never before, revealing their internal complexities, and has already led to the detection of a galactic wind during the instrument’s commissioning run.

At the core of SAMI is the hexabundle, developed by the USyd astrophotonics group led by our Associate Investigator Prof Joss Bland-Hawthorn, which is a combination of 61 (or more) individual optical fibres close-packed and fused to generate a powerful imaging device.

“Using multiple hexabundles simultaneously, we have been able to collect the largest ever resolved, near-by galaxy sample” said University of Sydney CAASTRO researcher Dr Julia Bryant (see photo on left) who worked on innovative ways to manufacture this new technology together with PhD student Sam Richards.

A key part of the SAMI collaboration has been Dr Jon Lawrence and his instrument science team at the Australian Astronomical Observatory (AAO), where the SAMI hexabundles were combined with a fibre spectrograph called AAOmega on the Anglo-Australian Telescope.

“The complete SAMI Galaxy Survey will lead to a new era in our understanding of galaxies”, concludes Professor Croom.

New technologies, such as SAMI, have the potential to revolutionize our understanding in this research field by tracing the motion of gas and stars, measure the rate at which new stars are being born, discover where heavy elements are located, and reconstruct the history of star formation.

The SAMI Galaxy Survey is part of “The Evolving Universe” research theme of CAASTRO.