Rotating White Dwarfs as Dark Matter Detectors

We show that rotating white dwarfs admixed with dark matter have interesting properties that may be used to reveal the presence of dark matter. Even though such objects follow universal relations among the $I$ (moment of inertia), Love (tidal Love number), and $Q$ (quadrupole moment) that are robust with respect to different normal matter equations of state, these relations are sensitive to the dark matter fraction. Since each white dwarf may have a different dark matter fraction, the $I-\text{Love}-Q$ relations for dark matter admixed white dwarfs span bands above those without dark matter admixture. Furthermore, the limiting mass of dark matter admixed rotating white dwarfs can be increased beyond those without any dark matter for some rotational rules. Ultra-massive white dwarfs with a total mass of at least $2.6$ $M_{\odot}$ could be formed. The accretion-induced collapse of such an object may lead to a $2.6$ $M_{\odot}$ compact object, such as the one discovered in the gravitational-wave event GW190814.Comment: 16 pages, 9 figure