GW-EOS WGセミナー
2 イベント
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セミナー
Impact of the relativistic Cowling approximation on shear and interface modes of neutron stars
2025年3月18日(火) 11:00 - 12:30
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.
会場: セミナー室 (359号室) (メイン会場) / via Zoom
イベント公式言語: 英語
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セミナー
Dark Matter and Neutron Stars: A Gravitational Laboratory for the Unknown
2024年12月18日(水) 10:00 - 11:30
Ankit Kumar (高知大学 理工学部 学振外国人特別研究員)
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.
会場: via Zoom
イベント公式言語: 英語
2 イベント