Franco Vazza (University of Bologna)
New clues on the origin of cosmic magnetism from large-scale structures: a smooking gun from primordial magnetic fields?
Friday, February 14th, 2025, 11:30am – Stasi lecture room (ICTP, Leonardo building) & streaming
Abstract. The rarefied medium in between galaxies and clusters of galaxies is permeated by magnetic fields. These fields are robustly observed but their ultimate origin is debated since a few decades. Are they be the result of galaxy evolution or of cosmic batteries? Or were these magnetic fields put in place by high energy processes in the primordial Universe? The new extragalactic radio surveys with precursors and pathfinders of the Square Kilometre Array have already started giving us an unprecedented tool to study the origin of cosmic magnetism. I will show that their recent results, combined with new realistic simulations of the cosmic web and higher energy probes in the gamma-ray window, are collectively hinting to a primordial origin of cosmic magnetism, with exciting implications for cosmology, galaxy formation and cosmic rays physics.
Contact: Piero Ullio
Video
Astrid Eichhorn (Heidelberg University)
Probing Quantum Gravity at all Scales
Friday, November 15th, 2024, 11:30am – Aula D (old SISSA building) & streaming
Abstract. To make progress in our understanding of the quantum structure of spacetime, we need observational tests of proposed theories of quantum gravity. However, this is challenging, because the Planck scale is many orders of magnitude removed from scales that we can probe directly with observations. Thus, we require lever arms that translate Planck-scale predictions into predictions at observationally accessible scales. In my talk, I will use asymptotically safe quantum gravity as a case study. I will show, how the interplay of quantum gravity with matter (both visible and “dark”) shapes the properties of matter fields in and beyond the Standard Model at the Planck scale. I will then show how to translate these Planck-scale predictions into predictions of Standard-Model properties as well as predictions about the properties of the dark matter and the dark energy.
Contact: Piero Ullio
Video
Mark Hindmarsh (University of Helsinki & University of Sussex)
Gravitational waves from early universe phase transitions
Friday, October 11th, 2024, 11:30am – Aula D (old SISSA building) & streaming
Abstract. A few picoseconds after the beginning of the Universe, the Higgs field turned on. In extensions of the Standard Model of particle physics, this could have been a first order phase transition, with the spontaneously nucleated bubbles of the Higgs phase expanding and colliding at relativistic speeds. The resulting sound waves would have been a powerful source of gravitational radiation. I will survey ongoing work to characterise the spectrum of gravitational radiation from early universe phase transitions, prospects for observing the radiation at the future space-based gravitational wave detector LISA, and outline how LISA can complement the LHC as a probe of phase transitions and physics beyond the Standard Model.
Contact: Enrico Morgante
Video
Stefano Profumo (University of California, Santa Cruz, and Santa Cruz Institute for Particle Physics)
The Primordial Black Holes Variations
Friday, October 4th, 2024, 11:30am – Stasi lecture room (ICTP) & streaming
Abstract. In the era of gravitational wave astronomy and direct black hole imaging, the possibility that some of the black holes in the universe have a primordial, rather than stellar, origin, and that they might be a non-negligible fraction of the cosmological dark matter, is both timely and intriguing. I will review the status of the field, describe search strategies and future prospects for detection across many decades in black hole mass, discuss how light primordial black holes could seed both baryonic and particle dark matter in the very early universe, and comment on how the search for primordial black holes may lead to a deeper understanding of the elusive Galactic “rogue planets”.
Contact: Piero Ullio
Video
Kazuya Koyama (University of Portsmouth)
Observational probes of dark energy and modified gravity models
Friday, September 13th, 2024, 11:30am – Aula D (old SISSA building) & streaming
Abstract. The discovery of the accelerated expansion of the Universe has come relatively late in our study of the cosmos, but in showing that gravity can act repulsively, it has opened up many new questions about the nature of gravity and what the Universe might contain. Is the acceleration being driven by dark energy? Or is general relativity itself in error, requiring a modification at large scales to account for the late acceleration? Structure formation in our Universe can be different even if the geometry of the homogeneous and isotropic universe is the same in these two classes of models, offering a possibility to distinguish between them observationally. I will discuss cosmological tests of dark energy and modified gravity models using latest cosmological observations.
Contact: Emilio Bellini
Video
Erminia Calabrese (Cardiff University)
Cosmology in the era of Cosmic Microwave Background Polarization
Friday, September 6th, 2024, 11:30am – Aula D (old SISSA building) & streaming
Abstract. We discuss the opportunities for cosmology in light of the start of the Stage III+ CMB observations, targeting primordial gravitational waves and lensing. We highlight the near and far future objectives, describing the opportunities for combining CMB probes, in this and the next decade, with Large Scale Structure surveys.
Contact: Carlo Baccigalupi
Video – Slides