Colloquium APC

An Earth Climate Changes Overview Including Anthropic Ongoing Climate Evolution

This seminar will illustrate how modelling the Earth system helps us understand the climate changes our planet has undergone throughout its long history. We will focus in particular on the principles that regulate temperatures and the hydrological cycle over billions, millions, and hundreds of thousands of years, making sustainable life on Earth possible. However, human kind has risen to become a major driver of climate change, with the distinct characteristic that its impacts on the environment are rapid and, in the long term, threatens humanity. We will compare long-term, natural changes with the ongoing anthropogenic changes.

The first massive black holes: recent discoveries and open questions

The presence of massive black holes in the first galaxies has been predicted theoretically for many years. Until the launch of the space telescope JWST the bulk of observational data hinged on very bright sources — luminous quasars — detected about one billion years after the Big Bang. Now a large number of fainter sources, candidate active massive black holes, have been identified, some at much earlier cosmic times. The extent of the population as well as their peculiar properties in terms of spectral distribution and compactness of the host galaxies challenge standard approaches.

APC Colloquium - LIGO and gravitational wave astronomy: ten years after the first detection

Ten years ago LIGO made the first direct detection of gravitational waves, emitted by the merger of two black holes about 1.3 billion years ago. Now, over 300 gravitational wave events have been observed by the LIGO-Virgo-KAGRA collaborations. Earlier this year, gravitational waves were detected from a black hole merger very similar to that first event in 2015, but this time with three times higher signal-to-noise ratio. This was thanks to the improvements in sensitivity that have been achieved in LIGO and Virgo in the past decade.

FASER: Looking Forward to New Physics at the LHC

FASER is a small experiment that was installed into the Large Hadron Collider (LHC) complex at CERN in 2021. The experiment has been taking proton collision data during LHC Run 3 (2022-to-date) with the aim to search for light new particles and to study, for the first time, neutrinos produced at a particle collider. In this colloquium I will describe the physics motivation, the experiment design and the physics results released by FASER over the last years, as well as touching on the future with possible detector upgrades.

Gravity in the era of Precision Cosmology

Stage IV Large Scale Structure Surveys are ushering in a new era of precision cosmology! In this talk, I will explore the effort to test gravity on cosmological scales, highlighting the theoretical advancements aimed at constructing an optimal framework. I will also touch on the synergy with gravitational wave surveys. Additionally, I will provide a detailed review of recent findings based on currently available data and conclude with an outlook on the challenges and future prospects in this field.

APC colloquium : The modeling of stellar explosions : How to connect the central engine to multi-messenger observations

The gravitational collapse of massive stars can lead to extreme stellar explosions when both fast rotation and strong magnetic fields are present during the onset of the supernova. This scenario is particularly important when it comes to exceptional sources such as hypernovae and long gamma-ray bursts, whose very high energy release can only be explained by progenitors with the most extreme physical conditions.

Colloquium APC