72 research outputs found
Transmuted Gravity Wave Signals from Primordial Black Holes
Primordial black holes (PBHs) interacting with compact stars in binaries lead
to a new class of gravity wave signatures that we explore. A small PBH captured by a neutron star or a white dwarf will
eventually consume the host. The resulting black hole will have a mass of only
, not expected from astrophysics. For a double neutron
star binary system this leads to a transmutation into a black hole-neutron star
binary, with a gravity wave signal detectable by the LIGO-VIRGO network. For a
neutron star-white dwarf system this leads to a black hole-white dwarf binary,
with a gravity wave signal detectable by LISA. Other systems, such as
cataclysmic variable binaries, can also undergo transmutations. We describe
gravity wave signals of the transmuted systems, stressing the differences and
similarities with the original binaries. New correlating astrophysical
phenomena, such as a double kilonova, can further help to distinguish these
events. This setup evades constraints on solar mass PBHs and still allows for
PBHs to constitute all of the dark matter. A lack of signal in future searches
could constrain PBH parameter space.Comment: 8 pages, 1 figure; published versio
Positrons from Primordial Black Hole Microquasars and Gamma-ray Bursts
We propose several novel scenarios how capture of small sublunar-mass
primordial black holes (PBHs) by compact stars, white dwarfs or neutron stars,
can lead to distinct short gamma-ray bursts (sGRBs) as well as microquasars
(MQs). In addition to providing new signatures, relativistic jets from these
systems will accelerate positrons to high energies. We find that if PBHs
constitute a sizable fraction of DM, they can significantly contribute to the
excess observed in the positron flux by the Pamela, the AMS-02 and the
Fermi-LAT experiments. Our proposal combines the beneficial features of
astrophysical sources and dark matter.Comment: 9 pages, 2 figures, v2: significant revisions, published version,
Physics Letters B (2018
Beyond Minimal Lepton Flavored Dark Matter
We consider a class of flavored dark matter (DM) theories where dark matter
interacts with the Standard Model lepton fields at the renormalizable level. We
allow for a general coupling matrix between the dark matter and leptons whose
structure is beyond the one permitted by the minimal flavor violation (MFV)
assumption. It is assumed that this is the only new source of flavor violation
in addition to the Standard Model (SM) Yukawa interactions. The setup can be
described by augmenting the SM flavor symmetry by an additional
, under which the dark matter transforms. This
framework is especially phenomenologically rich, due to possible novel
flavor-changing interactions which are not present within the more restrictive
MFV framework. As a representative case study of this setting, which we call
"beyond MFV" (BMFV), we consider Dirac fermion dark matter which transforms as
a singlet under the SM gauge group and a triplet under .
The DM fermion couples to the SM lepton sector through a scalar mediator
. Unlike the case of quark-flavored DM, we show that there is no
symmetry within either the MFV or BMFV settings which
automatically stabilizes the lepton-flavored DM. We discuss constraints on this
setup from flavor-changing processes, DM relic abundance as well as direct and
indirect detections. We find that relatively large flavor-changing couplings
are possible, while the dark matter mass is still within the phenomenologically
interesting region below the TeV scale. Collider signatures which can be
potentially searched for at the lepton and hadron colliders are discussed.
Finally, we discuss the implications for decaying dark matter, which can appear
if an additional stabilizing symmetry is not imposed.Comment: 30 pages, 12 figures; minor corrections, added references and
discussion on decaying dark matter, matches published versio
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