The 2023 ESA Distinguished Lecture will feature Aurora Simionescu (Netherlands Institute for Space Research) who will present her lecture on Why Doesn’t the Universe Have More Stars.

Dr. Simionescu is an astrophysicist at the Netherlands Institute for Space Research (SRON) through the Women In Science Excel (WISE) Fellowship program of The Netherlands Organisation for Scientific Research (NWO). She is also a visiting scientist at Leiden University, and an affiliate member of the Kavli Institute for the Physics and Mathematics of the Universe at the University of Tokyo, Japan.

Prior to her current appointments, she spent five years at the Institute of Space and Astronautical Sciences of the Japan Aerospace Exploration Agency (JAXA), and four years as an Einstein Postdoctoral Research Fellow at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University. She completed her PhD research at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.

Her main research interests are related to the physics of the hot plasma in clusters of galaxies, the largest virialized objects in the universe. She also maintains earthinpink.com, a travel photography and astronomy blog.

Title: Why Doesn’t the Universe Have More Stars?
Abstract: Stars represent only a small fraction of the atoms in today’s Universe. Most of the normal matter resides, instead, in a dilute plasma located around and between galaxies throughout the cosmic web. Shocks and turbulence generated during the hierarchical growth of large-scale structure are thought to be responsible for heating the majority of baryons so that they are too hot to collapse into stars. Even when the radiative cooling time is short, feedback from supermassive black holes and supernovae re-heat the gas, or expel it from the host dark matter haloes, further impacting the process of star formation. Without understanding why so many atoms don’t end up in stars, we wouldn’t truly understand why some do.

Over the last few decades, space-based X-ray observatories have made important progress in mapping the thermodynamics and chemical composition of the hot intergalactic medium. I will summarise some of the main things we have learned about shocks, turbulence, and feedback, with a focus on results from ESA’s XMM-Newton satellite but also looking to other X-ray missions with European involvement, such as Chandra, Suzaku, and Hitomi. These discoveries pave the way for a future ESA-led large-class observatory, whose improved sensitivity and high spectral resolution integral field spectroscopy capabilities will push our study of the hot Universe to new frontiers.

The ESA Office established the ESA Distinguished Lecture Series in 2021. The series aims to showcase the science from ESA missions, recognize talented early-career European astronomers, and foster collaborations in the broader international community. Each lecture will feature an in-person visit at STScI, where the Distinguished Lecturer will have the opportunity to meet with staff, students, and postdocs. The lecture will be held at STScI in the Bahcall Auditorium.