UC Berkeley

The empirical study of ultraheavy dark matter (DM) requires astrophysical probes. We present here a detailed study of DM-induced type Ia supernovae as one such probe. Dark matter may heat a small region in a white dwarf (WD) sufficient to trigger runaway fusion and ignite a supernova. We consider DM candidates that heat through the production of high-energy standard model (SM) particles, and show that such particles efficiently thermalize the WD medium and ignite supernovae. Based on the existence of long-lived WDs and the observed supernovae rate, we put new constraints on ultra-heavy DM candidates with masses above 10^{16} GeV that produce SM particles through annihilation, decay, and DM-SM scattering in the stellar medium. As a concrete example, this rules out supersymmetric Q-ball DM in parameter space complementary to terrestrial bounds. We further consider the possibility of DM capture by WDs, leading to the formation and self-gravitational collapse of a DM core within the star. This process allows two additional mechanisms for DM-induced particle heating, which we study here. For asymmetric DM, such a core may form a black hole that ignites a supernovae via Hawking radiation. For DM with a sufficiently small but nonzero annihilation cross section the core may cause ignition via a burst of annihilation during gravitational collapse. These processes are sensitive to much less massive candidates, down to 10^7 GeV, than are the mechanisms involving a single DM particle. It is also intriguing that these DM-induced ignition scenarios provide an alternative mechanism of triggering supernovae from sub-Chandrasekhar mass progenitors.