Speaker: Emmanuel Schaan

Dr Emmanuel Schaan: Staff Scientist at SLAC National Accelerator Laboratory

A Cosmic Shadow Theater: How Galaxy Silhouettes Reveal Their Dark Side

Using the Cosmic Microwave Background to reveal the invisible components of galaxies to shed light on the nature of Dark Matter, Dark Energy and the formation of galaxies.

Free and open to the public.

About 13.8 billion years ago, our universe ballooned outward at an incredible speed. Everything we observe today, which had been packed tightly together, expanded in a roiling mass of light and particles. It took 380,000 years for this hot, dense soup to thin and cool enough to allow light to travel through it. This first light, dating back to the formation of early atoms, is called the cosmic microwave background (CMB) and reflects the initial conditions of the universe. This afterglow from the Big Bang, the CMB, also acts as the backlight in a shadow theater where galaxies are the protagonists. The resulting galaxy shadows contain unique information about the invisible components of galaxies, such as their cold gas and dark matter, which hold clues to the nature of dark matter, dark energy, and the formation of galaxies. I will present some of the scientific efforts to reveal these galaxy silhouettes, using unprecedented cosmic microwave background experiments and galaxy surveys.

Dr Emmanuel Schaan is a staff scientist at SLAC National Accelerator Laboratory. As a cosmologist, he studies the origin and evolution of the universe by analyzing data from large telescopes in the U.S., Chile and space. His work focuses on the cosmic microwave background, the earliest light visible after the Big Bang, and on the large-scale distribution of galaxies. Schaan grew up in Paris, France. After studying at Ecole Normale SupĂ©rieure, he moved to Princeton, where he received his PhD. in 2017, and then worked as a Chamberlain Fellow at Lawrence Berkeley National Laboratory before joining SLAC in 2022. He loves astrophotography, tinkering, electronics and DIY