• Martine Schut

FotU symposium recap: Samaya Nissanke, Tina Pollmann and Stefan Teufel (morning program)

Watch back the talks by Samaya Nissanke, Tina Pollmann and Stefan Teufel below:

9:30 - 10:15: Samaya Nissanke

Title: New Perspectives onto the Universe in the era of Multi-Messenger Astrophysics

Abstract: In the past five years, the LIGO, Virgo and KAGRA gravitational wave (GW) detectors have announced the discovery of at least fifty compact object mergers including the first two binary neutron star mergers GW170817 and GW190425 and two neutron star black hole mergers GW200105 and GW200115. The discovery of both gravitational wave and electromagnetic (EM) radiation from the first binary neutron star merger, GW170817, has opened up a new era of multi-messenger GW+EM astronomy. The EM follow-up campaign for this single event was unprecedented in terms of its scale, coordination and the resulting observational data-sets. Although only a single event, the follow-up and joint GW+EM characterization have offered us new perspectives on the Universe enabling critical insights into diverse fields from gravity, high-energy astrophysics, nuclear physics, to cosmology. In this talk, I will give an overview of the GW discovery and EM follow-up of this event and subsequent neutron star mergers, and then discuss how to place compact object mergers in their full astrophysical context using joint GW+EM measurements. I will conclude by discussing the lessons that we are learning from these neutron star binary mergers. Finally, I will provide my perspective on the remarkable opportunities and challenges that have emerged in this new observationally-driven and fast-paced field as we move from the discovery era to one of precision astrophysics in this decade.

10:15-11:00: Tina Pollmann

Title: Direct searches for Dark Matter

Abstract: The nature of approximately 27% of the mass-energy content of the universe, or 85% of the total mass in the universe, is currently unknown. Cosmological and astrophysical observations require this extra mass to account for the depths of gravitational potentials inferred from the velocities of astrophysical objects, the paths of light past astrophysical objects, and the structures in the cosmic microwave background. Observations consistently indicate that this extra mass cannot be the regular, or ‘baryonic’, matter we are familiar with. Assuming that this ‘dark matter’ is made from a new type of particle, the properties we can infer from astrophysical observations are that this particle is stable at timescales comparable to the age of the universe, does not interact via the strong or electro-weak forces, and is not accounted for in the standard model of particle physics. The hypothesis of dark matter as a new type of particle is currently favoured, since the existence of such a particle would explain not just astrophysical and cosmological observations, but could resolve inconsistencies in the standard model of particle physics at the same time. A global effort to detect this hypothetical dark matter particle and to study its properties has now been ongoing for several decades. Out of several experimental approaches, this lecture will focus on direct detection of a class of hypothetical particles called WIMPs - weakly interacting massive particles - that arise from attempts to mend inconsistencies in the standard model of particle physics, and happen to have the right properties to account for the dark matter content in the universe. In a direct detection experiment, a detector on earth is built for galactic WIMPs to interact in as earth passes through our galaxy's dark matter halo. To detect interactions between this very rarely interacting type of particle and our detector’s target material, extremely sensitive detectors with unprecedented control of interfering standard-model particles are being built in deep-underground laboratories. This lecture will explain the direct detection challenges and the most important experimental techniques currently in use.

11:15-12:00: Stefan Teufel

Title: Bohmian Mechanics from a Mathematician's Perspective

Abstract: Bohmian mechanics is a deterministic theory for the motion of point particles, more precisely a first-order nonautonomous dynamical system. Its relevance stems from the fact that one can show, by a relatively simple statistical equilibrium analysis, that the empirical predictions of this theory agree with those of the standard quantum mechanical measurement formalism when the latter makes unambiguous statements. In my talk I will review this "derivation" of the quantum measurement formalism from Bohmian mechanics, focusing on its mathematical structure and pointing to rigorous results.

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