Probing Neutron Star Interiors and the Properties of Cold Ultra-dense Matter with the SKAO

arXiv:2607.02597 · astro-ph.HE, astro-ph.IM · Submitted 2026-07-01 · Read on arXiv

Avishek Basu, Vanessa Graber, Marcus E. Lower, Marco Antonelli, Danai Antonopoulou, Manjari Bagchi, Prasanta Char, Paulo C. C. Freire, Brynmor Haskell, Huanchen Hu, David I. Jones, Banibrata Mukhopadhyay, Micaela Oertel, Nanda Rea, Violetta Sagun, Benjamin Shaw, Jaikhomba Singha, Benjamin W. Stappers, Tinn Thongmeearkom, Anna L. Watts, Patrick Weltevrede, The SKA Pulsar Science Working Group

astro-ph.HE, astro-ph.IM

Submitted: 2026-07-01

Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366) and arXiv:2512.16162

Code: https://github.com/cgca/rns

License: http://creativecommons.org/licenses/by-nc-sa/4.0/

The gist: Matter inside neutron stars is compressed to densities several times greater than nuclear saturation density, while maintaining low temperatures and large asymmetries between neutrons and protons.

Terminology

Abstract

Matter inside neutron stars is compressed to densities several times greater than nuclear saturation density, while maintaining low temperatures and large asymmetries between neutrons and protons. Neutron stars, therefore, provide a unique laboratory for testing physics in environments that cannot be recreated on Earth. To uncover the highly uncertain nature of cold, ultra-dense matter, discovering and monitoring pulsars is essential, and SKAO will play a crucial role in this endeavour. In this chapter, we will present the current state-of-the-art in dense matter physics and dense matter superfluidity, and discuss recent advances in measuring global neutron star properties (masses, moments of inertia, and maximum rotation frequencies) as well as non-global observables (pulsar glitches and free precession). We will specifically highlight how radio observations of isolated neutron stars and those in binaries -- such as those performed with SKAO in the near future -- inform our understanding of ultra-dense physics and address in detail how SKAO's telescopes unprecedented sensitivity, large-scale survey and sub-arraying capabilities will enable novel dense matter constraints. We will also address the potential impact of dark matter and modified gravity models on these constraints and emphasise the role of synergies between SKAO and other facilities, specifically X-ray telescopes and next-generation gravitational wave observatories.

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