Searching for Strange Quark Matter Objects Among White Dwarfs

TL;DR

This paper investigates the possibility of identifying strange quark dwarf stars among white dwarfs by analyzing their mass-radius relation, leading to the identification of seven candidate objects with smaller radii than typical white dwarfs.

Contribution

The study introduces a method to distinguish strange quark dwarfs from white dwarfs based on their unique mass-radius relation and reports seven candidate objects.

Findings

Seven strange dwarf candidates identified based on mass-radius analysis.

Candidates have masses of 0.02-0.12 solar masses and radii of 9,000-15,000 km.

Candidates are smaller in radius compared to typical white dwarfs of similar mass.

Abstract

The ground state of matter may be strange quark matter (SQM), not hadronic matter. A whole sequence of SQM objects, ranging from strange quark stars and strange quark dwarfs to strange quark planets, can stably exist according to this SQM hypothesis. A strange dwarf has a mass similar to that of a normal white dwarf but could harbor an extremely dense SQM core (with a density as large as $\sim \rm 4\times10^{14}\,g\,cm^{-3} $) at the center so that its radius can be correspondingly smaller. In this study, we try to search for strange dwarfs among the observed "white dwarfs" by considering their difference in the mass-radius relation. Seven strange dwarf candidates are identified in this way, whose masses are in the range of $\sim 0.02$ -- $0.12 M_{\odot}$, with the radii narrowly distributed in $\sim$ 9,000 -- 15,000 km. The seven objects are LSPM J0815+1633, LP 240-30, BD+20 5125B, LP 462-12, WD J1257+5428, 2MASS J13453297+4200437, and SDSS J085557.46+053524.5. Compared with white dwarfs of similar mass, these candidates are obviously smaller in radius. Further observations with large radio/infrared/optical telescopes on these interesting candidates are solicited.