Compact dwarfs made of light-quark nuggets

TL;DR

This paper models the properties and stability of compact dwarfs composed of light-quark nuggets, revealing their structural stability, mass-radius relations, and oscillation frequencies, which are comparable or higher than those of white dwarfs.

Contribution

It introduces a systematic approach to studying light-quark nugget-based compact dwarfs, including their structure, stability, and oscillation characteristics, using an equivparticle model and mean-field approximation.

Findings

Compact dwarfs made of light-quark nuggets are stable against fusion.

Their masses and radii are comparable to or larger than white dwarfs.

Radial oscillation frequencies are higher than those of traditional white dwarfs.

Abstract

Utilizing an equivparticle model with both linear confinement and leading-order perturbative interactions, we obtain systematically the properties of strangelets and nonstrange quark matter ($ud$QM) nuggets at various baryon ($A$) and charge ($Z$) numbers, where the detailed single-quark-energy levels are fixed by solving Dirac equations in mean-field approximation (MFA). We then examine the structures of compact dwarfs made of light strangelets or $ud$QM nuggets forming body-centered cubic lattices in a uniform electron background. Despite the strangelets and $ud$QM nuggets generally become more stable at larger $A$, the compact dwarfs are still stable since the fusion reactions between those objects do not take place in the presence of a Coulomb barrier, which is similar to the cases of light nuclei in normal white dwarfs. If $ud$QM dwarfs or strangelet dwarfs are covered with normal matter, their masses and radii become larger but do not exceed those of ordinary white dwarfs. Finally, we investigate the radial oscillation frequencies of $ud$QM dwarfs and strangelet dwarfs, and find that their frequencies are typically higher than traditional white dwarfs. The stability of compact dwarfs are then analysised by examining radial oscillation frequencies of the fundamental mode, where compact dwarfs covered by normal matter are still stable.