SAMI Maps Our Nearby Universe (Cosmology)

Our Monthly Media for June comes from Dr Sam Vaughan, from our University of Sydney node, on the final data release from the SAMI galaxy survey led by Professor Scott Croom, also at the University of Sydney. SAMI has observed over three thousand nearby galaxies in exquisite detail, studying the orbits of their stars, the properties of their interstellar gas and the kind of chemical elements which their stars are made from.

Using observations from Siding Springs observatory in rural New South Wales, SAMI is able to measure a “3D” view of its targets by taking a spectrum from many different locations in a single galaxy at the same time. This means that astronomers can build a picture of the complicated motions and orbits of stars in these galaxies, as well as investigating whether stars in the inner regions of galaxies are different from those in the outskirts.

In particular, SAMI has been a game changer for studying why the stars in some galaxies rotate together in a nice, ordered manner whilst the stars in other galaxies seem to have been thrown together in a jumbled mess. SAMI has produced one of the largest ever collections of galaxies with these measurements, and is finding tentative hints that the local environment a galaxy lives in plays a role in determining the orbits of its stars. Getting to the bottom of this question is key to understanding how the galaxies in our Universe were born and have evolved throughout their lifetimes.

This final data release is a product of over ten years of effort from nearly 100 astronomers, both within in Australia and around the world. Congratulations to Scott and the SAMI team for all their hard work!

Featured image: Data from the SAMI galaxy survey. Each of these points is the map of the interstellar gas in a galaxy from the survey. The galaxies are arranged by whether they are very low mass (on the left) or high mass (the right) and whether they live in an area full of lots of other galaxies (at the top) or not (at the bottom). The colour of the map tells you whether the gas contains a large fraction of heavy elements (red) or whether this fraction is low (blue). The four points at the top are zoomed-in versions of four galaxies in the survey, showing how a galaxy’s fraction of heavy elements can vary within a single object. © ASTRO3D


Provided by Astro 3D

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