  The transit of primordial black holes through a white dwarf causes localized
heating around the trajectory of the black hole through dynamical friction. For
sufficiently massive black holes, this heat can initiate runaway thermonuclear
fusion causing the white dwarf to explode as a supernova. The shape of the
observed distribution of white dwarfs with masses up to $1.25 M_{\odot}$ rules
out primordial black holes with masses $\sim 10^{19}$ gm - $10^{20}$ gm as a
dominant constituent of the local dark matter density. Black holes with masses
as large as $10^{24}$ gm will be excluded if recent observations by the NuStar
collaboration of a population of white dwarfs near the galactic center are
confirmed. Black holes in the mass range $10^{20}$ gm - $10^{22}$ gm are also
constrained by the observed supernova rate, though these bounds are subject to
astrophysical uncertainties. These bounds can be further strengthened through
measurements of white dwarf binaries in gravitational wave observatories. The
mechanism proposed in this paper can constrain a variety of other dark matter
scenarios such as Q balls, annihilation/collision of large composite states of
dark matter and models of dark matter where the accretion of dark matter leads
to the formation of compact cores within the star. White dwarfs, with their
astronomical lifetimes and sizes, can thus act as large space-time volume
detectors enabling a unique probe of the properties of dark matter, especially
of dark matter candidates that have low number density. This mechanism also
raises the intriguing possibility that a class of supernova may be triggered
through rare events induced by dark matter rather than the conventional
mechanism of accreting white dwarfs that explode upon reaching the
Chandrasekhar mass.
