Program 2021

Cecilia Ceccarelli, Université Grenoble Alpes, IPAG

The Solar System was born 4.5 billions years ago, after a complex process whose details are not fully understood. The large number of detected extrasolar planets tells us that they are a common product of the star formation process, their variety that there are many ways of building them. How can then we recover the path followed by the Solar System?

Understanding the Solar-type star formation process currently taking place in the Milky Way is mandatory to answer this question. Astrochemistry, the science of how atoms and molecules combine  and evolve in the interstellar medium, is a powerful diagnostics to follow the evolution that turns a molecular cloud dense clump into a planetary system. But it can only be exploited once we know how to interpret the chemistry occurring in the exotic conditions of the interstellar medium, where quantum chemical effects dominate.

In this presentation, I will provide an overview of the major progresses of our understanding in astrochemistry and, more specifically, the one involved in the Solar System formation history.

Razmik Mirzoyan, Max Planck Institute for Physics, Munich, Germany

Thirty-two years ago a report about the measurement of unusual, so-called teraelectronvolt signal from the Crab Nebula captured the attention of the world scientific community. The authors reported a flux of so-called gamma-ray photons, where each carried an incredible amount of energy, exceeding that of the well-known X-rays by billion times. How and in which processes the nature managed to pack such a huge energy content into single photons remained a mystery for the coming years. Researchers used for observations a special technique and instrumentation dubbed as imaging atmospheric Cherenkov telescopes. In the following couple of years not much has happened and the community started speculating about the new science of a single source. More researchers joined that effort and already ten years after the initial discovery ~10 sources of teraelectronvolt gamma-rays were known. Today this discipline boasts to know more than 200 sources of very different origin, from supernova remnants to pulsars, from supermassive active galactic nuclei with black holes in their centre to gamma-ray busts, from binary systems to pulsar wind nebulae. A new discipline, the so-called astro-particle physics with diverse instrumentation appeared in the cross-roads between physics and astrophysics. In this lecture we will have a closer look to the details of this rapidly evolving, fascinating frontier science.

Benedetta Ciardi, Max Planck Institute for Astrophysics

Cosmic reionization is the last major phase transition undergone by our Universe. Although most studies agree on the general characteristics of H reionization (for example that it is driven by stars and it is mostly if not fully complete by z~6), its details are still largely unknown, among which the contribution from and role played by more energetic sources.

In this talk I will discuss the ingredients needed for a correct modeling of cosmic reionization and present results from recent radiative transfer simulations accounting for a variety of source types (such as stars, quasars, X-ray binaries). I will then discuss the observability of reionization in terms of various diagnostics associated to the 21cm signal from neutral hydrogen and present the latest results from the LOFAR radio telescope.

Joseph Silk, Institut d’Astrophysique de Paris, The Johns Hopkins University, University of Oxford

One of the greatest challenges in cosmology is understanding the origin of the structure of the universe. The cosmic microwave background and large-scale surveys of galaxies have provided unique windows for probing cosmology and its inflationary origin. But where do we go next? Future experiments are planned with the next generation of observatories that will increase the current precision of cosmological measurements by an order of magnitude. However we need to do far better if there is to be a guaranteed science return that will definitively probe our cosmic origins. I shall argue that the ultimate goal for our future strategy must be astronomy from lunar-based telescopes.