XIIIth International Symposium on Nuclear Symmetry Energy (NuSym25)

Exploring surface properties of neutron stars using the coherent density fluctuation model

9 Sept 2025, 16:50

2h 10m

Auditorium (8F) (Integrated Innovation Building (IIB), RIKEN Kobe Campus)

8. Theory of compact stars, including neutron star mergers and supernovae NuSym Poster Session

Speaker

Mr Praveen Kumar Yadav (Thapar Institute of Engineering and Technology)

Description

Neutron stars serve as unique astrophysical laboratories for probing the equation of state (EoS) of matter under extreme density and isospin asymmetry [1]. Understanding their surface characteristics, particularly the surface incompressibility and surface symmetry energy, provides vital constraints on nuclear interactions far from saturation conditions. This study utilizes the coherent density fluctuation model (CDFM), originally formulated for finite nuclei [2-5], to explore these surface properties in neutron stars. Within CDFM formalism, the neutron star is treated as a macroscopic analogue of a finite nucleus, enabling the translation of nuclear matter properties, derived from an underlying energy density functional (EDF), from momentum space to the coordinate space description of the star's surface region.
We employ a range of EDFs based on established Skyrme interactions, specifically selecting 16 parameter sets that satisfy constraints derived from symmetric nuclear matter and pure neutron matter properties [6]. The macroscopic structure, including mass-radius profiles, is determined for each EoS by solving the Tolman-Oppenheimer-Volkoff (TOV) equations [1]. Subsequently, the CDFM formalism is applied, using the calculated neutron star density profiles, to compute the surface incompressibility and symmetry energy.
Our analysis focuses on the dependence of these surface quantities on the neutron star's total mass and the specific Skyrme parameterization used, highlighting the sensitivity to the stiffness of the EoS. The results demonstrate the successful application of the CDFM framework across vastly different scales, bridging the physics of finite nuclei and compact stars, and reinforcing its utility in nuclear astrophysics investigations.

References
[1] N. K. Glendenning, Compact stars (Springer 1997).
[2] M. K. Gaidarov et al., Phys. Rev. C 85, 064319 (2012).
[3] M. Bhuyan et al., Phys. Rev. C 97, 024322 (2018).
[4] P. K. Yadav, R. Kumar, and M. Bhuyan, Chin. Phys. C 46, 084101 (2022).
[5] P. K. Yadav, R. Kumar, and M. Bhuyan, Europhysics Letter 146, 14001 (2024).
[6] M. Dutra et al., Phys. Rev. C 85, 035201 (2012).