Affiliation: IISER-Bhopal, India

Title: Correlations of nuclear matter EOS with the non-radial f mode oscillations of neutron stars

Abstract: Constraining the equation of state of a neutron star is a big question. We will discuss that the measurements of mode oscillations can constraint the different parts of the equation of state. We investigate the intricate relationships between the non-radial f mode oscillation frequencies of neutron stars (NS)s and the corresponding nuclear matter equation of state (EOS) using a machine learning (ML) approach within the ambit of the relativistic mean field (RMF) framework for nuclear matter. With two distinct parameterizations of the Walecka model, namely, (1) with non-linear self interactions of the scalar field (NL) and, (2) a density dependent Bayesian model (DDB), we perform a thorough examination of the f mode frequency in relation to various nuclear saturation properties. The correlations between the f mode frequencies and nuclear saturation properties reveal, through various analytical and ML methods, the complex nature of NSs and their potential as the cosmic laboratory for studying extreme states of matter.

Affiliation: University of Frankfurt, Germany

Title: Effective Field Theory Approach to Binary Systems in Scalar-Tensor Theories

Abstract: Theories beyond General Relativity typically contain at least one additional scalar degree of freedom, effectively mediating an additional force. While this force must be highly suppressed in low-density environments--to pass current constraints--it generically leads to deviations from General Relativity in high-density / high-curvature environments, such as neutron stars and black holes, and thus impacts their observables. I will discuss how binary systems in scalar-tensor theories can be treated using an effective field theory approach and present results regarding observables such as the energy loss and the gravitational wave spectrum.