GW-EOS WG Seminar
3 events
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Seminar
Pairing in Bose-Fermi and Fermi-Fermi systems
November 6 (Thu) 15:00 - 16:30, 2025
Pierbiagio Pieri (Associate Professor, Dipartimento di Fisica e Astronomia “Augusto Righi”, Università di Bologna, Italy)
This seminar is co-hosted by GWX-EOS Working Group and iTHEMS-ABBL Joint Astro Study Group. Abstract: In the first part of my talk, I will review recent work on Bose-Fermi mixtures with an attractive interaction inducing pairing between bosons and fermions. After discussing a recent experiment on this system [1], which has confirmed predictions obtained by us some time ago within a many-body diagrammatic approach [2], I will present novel results for the compressibility [3] that suggest a metastable nature for the many-body phase observed in [1]. Then, I will discuss the extension of our calculations to two-dimensional Bose-Fermi mixtures [4,5]. The results obtained in 2D challenge previous beliefs formulated for 3D systems. In the second part, I will discuss attractive polarized Fermi systems, for which the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase was proposed many years ago as a possible superfluid phase. I will discuss how significant precursor FFLO fluctuation effects appear already in the normal phase of polarized Fermi gases at finite temperature [6], and how they could be experimentally detected with ultracold gases. At zero temperature [7], I will discuss how the quasi-particle parameters of the normal Fermi gas change when approaching an FFLO quantum critical point, with a complete breakdown of the quasi-particle picture analogous to what found in heavy-fermion materials at an antiferromagnetic quantum critical point. Finally, I will discuss a recent joint experimental-theoretical work on the motion of a vortex orbiting a pinned anti-vortex in a strongly interacting Fermi gas [8], highlighting the interplay between Andreev bound states in the vortex core and delocalized thermal excitations in shaping the vortex dynamics.
Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359
Event Official Language: English
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Seminar
Impact of the relativistic Cowling approximation on shear and interface modes of neutron stars
March 18 (Tue) 11:00 - 12:30, 2025
Christian Kruger (Postdoctoral Researcher, University of Tuebingen, Germany)
Neutron stars are amongst the most compact objects known in the universe, which, therefore, require General Relativity for an accurate description. Seismic excitations of these stars may encode information about their currently unknown internal composition. As General Relativity is a mathematically complex theory, such oscillations are often considered in the Cowling approximation in which the spacetime is assumed to be static. In this talk, we will focus on shear and interface modes of neutron stars related to an elastic crust and investigate the impact of the Cowling approximation; we find that its impact on shear modes is negligible, while interface modes seem to experience some modification. Furthermore, we extend a scheme based on properties of Breit-Wigner resonances that allows to estimate the damping times of slowly damped modes. The proposed scheme is numerically robust and we compare it to estimates employing the quadrupole formula.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
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Seminar
Dark Matter and Neutron Stars: A Gravitational Laboratory for the Unknown
December 18 (Wed) 10:00 - 11:30, 2024
Ankit Kumar (Postdoctoral Fellow, Faculty of Science and Technology, Kochi University)
Dark matter (DM), a mysterious non-luminous component of the universe, dominates the mass distribution in galaxies and clusters yet remains elusive in its interactions beyond gravity. Neutron stars (NSs), among the most compact objects in the universe, provide unique astrophysical laboratories to investigate the interplay between DM and extreme matter due to their immense densities and gravitational fields. In this talk, I will briefly outline the mechanisms through which DM could be gravitationally captured by NSs, including during their formation and evolution. The primary focus will then shift to the structural and observable implications of DM admixed NSs. I will discuss the theoretical frameworks used to model DM admixed NSs and how DM parameters, such as particle mass and density profiles, modify the equation of state and structural stability of these stars. Observational constraints from pulsars like PSR J0740+6620 and gravitational wave events such as GW170817 will be highlighted as critical tools for deducing DM characteristics and testing theoretical model predictions. By presenting insights from recent studies, including our own work, this talk aims to demonstrate how astrophysical observations can constrain DM parameters and provide a deeper understanding of DM’s role in dense astrophysical environments. I will conclude with a discussion of future prospects for advancing both theoretical models and observational strategies in this interdisciplinary field.
Venue: via Zoom
Event Official Language: English
3 events