A new eye on the changing heavens

The Large Synoptic Survey Telescope (LSST) is one of the largest astronomy projects of the next decade. It aims to survey 10 billion galaxies out to a redshift of four including the ability to detect objects 100 times fainter than those seen with current large surveys. LSST will take pictures of the entire southern sky every few days for a decade, creating a motion picture of the heavens. Comparing these images will allow scientists to, for example, see when stars change in brightness or explode.

Standing outside AlbaNova, From the left, Ariel Goobar, Matthew Hayes, Jens Jache, Hiranya Peiris, Jesper Sollerman
From the left, Ariel Goobar, Matthew Hayes, Jens Jache, Hiranya Peiris, Jesper Sollerman

OKC researchers will be at the heart of this groundbreaking project thanks to a generous research project grant from the Knut and Alice Wallenberg (KAW) Foundation. The KAW project, entitled “Understanding the Dynamic Universe”, is led by Hiranya Peiris with Co-Is Ariel Goobar, Jesper Sollerman, Matthew Hayes, and Jens Jasche. It will allow OKC researchers to discover and study transient phenomena. Also, researchers will learn about dark matter by mapping its distribution and evolution and studying low surface brightness galaxies which are currently not explained in cold dark matter galaxy formation scenarios.

Hiranya says, “in the spirit of interdisciplinary collaboration underlying the Oskar Klein Centre, this grant will get researchers in the Physics and Astronomy Departments working together in new ways, bringing different strands of expertise to bear on some of the biggest questions in physics. I am particularly looking forward to that interdisciplinary aspect.”

Connecting the structure of the early universe, as seen in the cosmic microwave background, to the structures we see in the nearby universe is one of the goals of cosmology. This is complicated by the fact that galaxies are embedded in a web of dark matter whose structure is not explicitly visible. A detailed map of the dark matter distribution and its evolution can be made from the enormous LSST galaxy catalog using Bayesian Origin Reconstruction from Galaxies, a method developed by co-I Jens Jasche. Jens says, “for the first time, we might be able to discriminate between a cosmological constant and models of dark energy or large scale modifications of gravity that are believed to affect the growth of cosmological structures.“

Understanding the connection between galaxies and dark matter is important for probing the fundamental physics of the dark matter models we use today. Recently discovered types of low surface brightness, dark matter dominated, galaxies are unexplained in current cold dark matter models. Co-I Matthew Hayes says, “my part is to conduct a galaxy survey, targeting the lowest possible surface brightnesses we can reach. The ultra-deep co-adds from a telescope like LSST will be optimal for this kind of work, and the idea is to create a representative census of faint galaxies that are missing from surveys which used telescopes that are designed for compact source observations.”

Another LSST research focus at the OKC will be on rare cosmic explosions. Co-I Ariel Goobar says, “LSST will allow us to discover and study transient phenomena which are either too rare, too faint or too fast for existing telescopes. Some exciting objects we are sure to find are gravitationally lensed supernovae, from which we can measure the expansion rate of the Universe, and possibly detect the first generation of cosmic explosions. History also shows that opening new windows to the Universe is typically rewarded with the discovery of unknown phenomena. Exploration of short time-scales over large cosmic volumes could very well help us chart new physics territory. Ultimately, we hope to be able to resolve the dark matter and dark energy puzzles.”

Co-I Jesper Sollerman says, “LSST is really Big Science, and KAW grants are important for Swedish scientists who want to be part of such projects.”

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