par Perot, Loïc ;Chamel, Nicolas ;Vallet, Pierre
Référence Physical Review D - Particles, Fields, Gravitation and Cosmology, 107, page (103004)
Publication Publié, 2023-05-03
Article révisé par les pairs
Résumé : The advent of space-based gravitational-wave detectors like the Laser Interferometer Space Antenna will allow to observe signals most of which are expected to be emitted by white-dwarf binaries. Amongthese systems could be hidden another kind of compact objects, postulated by Glendenning, Kettner andWeber in 1995, containing a small core made of strange quark matter surrounded by layers of hadronic matter reaching densities much higher than in white dwarfs. These so called strange dwarfs cannot be easilydistinguished from white dwarfs through electromagnetic observations alone: their outermost envelopes are expected to have the same composition and their radii are quite similar (except for low masses). However, future measurements of the tidal deformability through gravitational-wave observationscould provide a new way to reveal their existence.In this paper, we revisit the structure and the tidal deformability of strange dwarfs in full generalrelativity taking into account the possible crystallization of their envelop. Unlike most previousstudies, we do not describe the hadronic layers using the equation of state of Baym, Pethick and Sutherland, which was originally designed for the outer crust of a neutron star. The conditions leading to such heavy elements in gravitational-core collapse supernova explosions are not expected to be met during the stellar evolution leading to the formation of strange dwarfs. Instead, we consider the same light elements as found in white dwarfs but we take into account electroncaptures by nuclei and possibly pycnonuclear fusions that may be triggered by compression. We find that the radius of strange dwarfs is systematically smaller than that of their white dwarf relatives. These deviations can be large for very low mass stars but mostly lie within the current observational uncertainties for typical white dwarf masses. On the other hand, the observable tidal deformability coefficient $Lambda_2$ is strongly reduced in comparison to white dwarfs and the deviation will be potentially measurable by future space-based gravitational detectors.

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