Neutron Star Equation of State with Exotic Phases and Oscillation Modes within the Astrophysical Constraints

• Applicant: Dr. Ishfaq Ahmad Rather, Ph.D.
• Subject Area: Astrophysics and Astronomy
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 579861443

This project aims to develop advanced theoretical models of the internal structure of neutron stars, focusing on the equation of state (EoS) that governs matter under extreme densities. The central objective is to investigate exotic Color Superconducting (CSC) phases of quark matter that may exist in neutron star cores. Using a state-of-the-art, renormalization-group consistent model, this project will move beyond analyzing static properties like mass and radius. Instead, its core novelty lies in exploring the star's dynamical properties by calculating quasi-normal oscillation modes (QNMs). This will provide the first systematic mapping between the parameters of advanced CSC models and the gravitational-wave signatures observable by current and future detectors. A key investigation will systematically test the robustness of quasi-universal relations (e.g., I-Love-Q). I will explore how sequential CSC phase transitions (2SC to CFL) can create discontinuities in the stellar profile, providing a clear physical mechanism for generating measurable deviations from these relations. Furthermore, the project will explore the impact of Dark Matter (DM) as a complementary probe of the dense matter EoS. A hierarchical strategy will be employed to disentangle the distinct observational imprints of CSC phases and DM, addressing the critical issue of signal degeneracy. Finally, the project will incorporate finite-temperature effects, essential for modeling proto-neutron stars and merger remnants. This investigation will focus exclusively on the thermal properties of the hybrid CSC equation of state, clarifying the behavior of baryonic matter in these hot, dense environments. This research is exceptionally timely, aligning with the rapid advances in multi-messenger astronomy from observatories like LIGO/Virgo/KAGRA. By combining robust theoretical models with a full suite of observational and experimental constraints (from astrophysics, heavy-ion collisions, and chiral effective field theory), this project will deliver falsifiable predictions and significantly advance our understanding of the fundamental physics governing the universe's densest matter.

• DFG Programme: Research Grants
• International Connection: India, Spain
• Cooperation Partners: Professorin Dr. Debarati Chatterjee, Ph.D.; Professorin Dr. Laura Tolos Rigueiro, Ph.D.
• Co-Investigator: Professor Dr. Jürgen Schaffner-Bielich, Ph.D.