8th Monthly Colloquium of Hellenic Astronomical Society (HelAS) – 11 May 2021
“Insights into Dark Matter and Dark Energy using Strong Gravitational Lensing observations of Galaxies, Quasars, and Supernovae”
by
Dr. Leonidas Moustakas (JPL/Caltech, USA)
Tuesday, 11 May 2021 at 18:00 Athens time (UTC + 3:00)
Click for ZOOM link
(Meeting ID: 958 6532 5338 and Passcode: 553124)
Abstract: The nature of dark matter and dark energy are lasting puzzles in physics and astrophysics. While these are part of the universe’s fundamental make-up, astrophysical observations offer insights through gravitational signatures and elegant measurements of cosmic distance. The phenomenon of strong gravitational lensing, predicted by Einstein decades before it was first observed in 1979, manifests when from our point of view, an astronomically-distant luminous object has a massive body between us. With the right combination of alignment, mass-distribution, and relative distances, the distant luminous object may be imaged into multiple images – each of which has a different light-travel time to us. We now know of thousands of strong gravitational lens systems. Their information content is extremely rich, with observations that match each system’s particular features. Specific dark matter particle p roperties are expected to leave fingerprints in the structure within galaxies and galaxy clusters, fingerprints that can be probed through their gravitational signature in gravitational lens systems. When the distant, lensed object is one that varies its brightness with time, such as a quasar or a supernova, we can see the changes in brightness repeat in turn across each of their multiple images. This can be used to measure cosmic distances with accuracy, which can teach us about the size of the universe over time – and dark energy. In this colloquium, I will introduce these concepts, where some current exciting work is leading us, and what we might expect over the next ten years.
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