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Dark Matter and the Dance of Dwarf Galaxies

Major galaxies, such as our cosmic home the Milky Way, the nearby Andromeda galaxy, or Centaurus A, are surrounded by swarms of smaller dwarf satellite galaxies. Over the past 15 years, our knowledge of these satellite galaxies has exploded. The number of known Milky Way satellites has quadrupled, and highly precise measurements of their motions have provided unprecedented insights into their complex orbital dance. In my research, I investigate the distribution and motion of satellite galaxies to test our ideas of how the cosmos in general, and galaxies in particular, have formed and evolved. Our current leading model of cosmology was largely developed on cosmic scales, and implies that most of the mass in the Universe is dominated by unknown stuff: Dark Matter. Based on this cosmological model, computer simulations can nowadays follow the emergence and evolution of structure in model universes. These simulations predict the distribution and properties of galaxies down to the smallest scales (astronomically speaking). They predict a highly chaotic tangle of satellite galaxies. In contrast, my research finds that the observed situation resembles an ordered choreography: the satellite galaxies around the Milky Way, Andromeda, and Centaurus A are aligned along planes. Many satellites also move along these structures in a common direction. This finding poses a serious challenge to our model of cosmology – and might point at a fundamental misinterpretation of cosmic proportions.

Marcel S. Pawlowski

My research is situated at the intersection of observations and cosmological simulations. I am most interested in testing our cosmological knowledge and our understanding of the properties and dynamics of dwarf galaxies with observations of nearby systems of satellite galaxies. After receiving my PhD from the University of Bonn in 2013, I moved to the United States for a postdoc position at Case Western Reserve University in Cleveland, Ohio. In 2016, I was awarded a NASA Hubble Fellowship to work at the University of California Irvine. At the end of 2018 I moved back to Germany to my current position as Schwarzschild Fellow at the Leibniz-Institute for Astrophysics in Potsdam.

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Uncovering the Death Throes of Massive Stars Through Supernovae

Stars more massive than about 10 solar masses explode at the end of their life and die as supernovae. How massive stars look like when they explode? Astronomers try to answer this question through supernovae. It has been recently recognized that massive stars seem to have an unexpectedly active life just before they explode. In this talk, I will introduce supernovae and what they tell us about the “death throes” of massive stars.

Takashi Moriya

I am an Assistant Professor at National Astronomical Observatory of Japan (NAOJ). I was born and grew up in Tokyo, Japan. I received my PhD in Astronomy from the University of Tokyo in 2013. I worked at University of Bonn in Germany as a postdoctoral research fellow from 2013 to 2016 and moved to NAOJ in 2016. My research interest is mainly in theoretical aspects of supernovae and stellar evolution, but I also work on observational astronomy using the Subaru telescope operated by NAOJ.

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