Alexander Kusenko
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View article: Primordial Black Hole Triggered Type Ia Supernovae. I. Impact on Explosion Dynamics and Light Curves
Primordial Black Hole Triggered Type Ia Supernovae. I. Impact on Explosion Dynamics and Light Curves Open
Primordial black holes (PBHs) in the asteroid-mass window are compelling dark matter candidates, made plausible by the existence of black holes and by the variety of mechanisms of their production in the early Universe. If a PBH falls into…
View article: Neutrino masses, matter-antimatter asymmetry, dark matter, and supermassive black hole formation explained with Majorons
Neutrino masses, matter-antimatter asymmetry, dark matter, and supermassive black hole formation explained with Majorons Open
The spontaneous breaking of a global lepton number symmetry can result in a (pseudo) Nambu-Goldstone boson known as the Majoron. We study a singlet Majoron model that couples to two Higgs doublets in which the lepton number current develop…
View article: Incentivizing supplemental math assignments and using AI-generated hints is associated with improved exam performance
Incentivizing supplemental math assignments and using AI-generated hints is associated with improved exam performance Open
Inequities in student access to trigonometry and calculus are often associated with racial and socioeconomic privilege, and often influence introductory physics course performance. To mitigate these disparities in student preparedness, we …
View article: Neutrinos and Gamma Rays from Beta Decays in an Active Galactic Nucleus NGC 1068 Jet
Neutrinos and Gamma Rays from Beta Decays in an Active Galactic Nucleus NGC 1068 Jet Open
We show that TeV neutrinos and high-energy gamma rays detected from the nearby active galaxy NGC 1068 can simultaneously be explained in a model based on the beta decays of neutrons produced in the photodisintegration of ^{4}He nuclei on u…
View article: Evidence for the Sombrero Galaxy as an Accelerator of the Highest-Energy Cosmic Rays
Evidence for the Sombrero Galaxy as an Accelerator of the Highest-Energy Cosmic Rays Open
Ultrahigh-energy cosmic rays (UHECRs) are the highest energy messenger from space, with energies exceeding 1 EeV. Although UHECRs were discovered over 60 years ago, their origin still remains a mystery. Pinpointing sources of UHECRs is cru…
View article: Black Holes from Fermi Ball Collapse
Black Holes from Fermi Ball Collapse Open
Fermi balls are non-topological solitons that can naturally form in an early universe containing a dark sector with heavy fermions and an attractive interaction mediated by a light scalar field. We compute the Fermi ball mass and radius sc…
View article: <i>JWST</i> lensed quasar dark matter survey – II. Strongest gravitational lensing limit on the dark matter free streaming length to date
<i>JWST</i> lensed quasar dark matter survey – II. Strongest gravitational lensing limit on the dark matter free streaming length to date Open
This is the second in a series of papers in which we use JWST Mid Infrared Instrument multiband imaging to measure the warm dust emission in a sample of 31 multiply imaged quasars, to be used as a probe of the particle nature of dark matte…
View article: Direct Collapse Supermassive Black Holes from Relic Particle Decay
Direct Collapse Supermassive Black Holes from Relic Particle Decay Open
We investigate the formation of high-redshift supermassive black holes (SMBHs) via the direct collapse of baryonic clouds, where the unwanted formation of molecular hydrogen is successfully suppressed by a Lyman-Werner (LW) photon backgrou…
View article: Revisiting formation of primordial black holes in a supercooled first-order phase transition
Revisiting formation of primordial black holes in a supercooled first-order phase transition Open
We reexamine production of primordial black holes in a supercooled phase transition. While a mere overdensity associated with a surviving false-vacuum patch does not imply formation of a black hole, it is possible for such a patch to evolv…
View article: High-redshift supermassive black holes from tiny black hole explosions
High-redshift supermassive black holes from tiny black hole explosions Open
Recent observations of the high-redshift universe have uncovered a significant number of active galactic nuclei, implying that supermassive black holes (SMBHs) would have to have been formed at much earlier times than expected. Direct coll…
View article: Neutrinos and gamma rays from beta decays in an active galactic nucleus NGC 1068 jet
Neutrinos and gamma rays from beta decays in an active galactic nucleus NGC 1068 jet Open
We show that TeV neutrinos and high-energy gamma rays detected from the nearby active galaxy NGC 1068 can simultaneously be explained in a model based on the beta decays of neutrons produced in the photodisintegration of 4He nuclei on ultr…
View article: The possibility of multi-TeV secondary gamma rays from GRB221009A
The possibility of multi-TeV secondary gamma rays from GRB221009A Open
The brightest gamma ray burst (GRB) ever observed, GRB221009A, produced a surprisingly large flux of gamma rays with multi-TeV energies, which are expected to be absorbed in interactions with extragalactic background light (EBL). If the hi…
View article: JWST Lensed quasar dark matter survey II: Strongest gravitational lensing limit on the dark matter free streaming length to date
JWST Lensed quasar dark matter survey II: Strongest gravitational lensing limit on the dark matter free streaming length to date Open
This is the second in a series of papers in which we use JWST MIRI multiband imaging to measure the warm dust emission in a sample of 31 multiply imaged quasars, to be used as a probe of the particle nature of dark matter. We present measu…
View article: New ideas on the formation and astrophysical detection of primordial black holes
New ideas on the formation and astrophysical detection of primordial black holes Open
Recently, a number of novel scenarios for primordial black hole (PBH) formation have been discovered. Some of them require very minimal new physics, some others require no new ingredients besides those already present in commonly considere…
View article: JWST lensed quasar dark matter survey – I. Description and first results
JWST lensed quasar dark matter survey – I. Description and first results Open
The flux ratios of gravitationally lensed quasars provide a powerful probe of the nature of dark matter. Importantly, these ratios are sensitive to small-scale structure, irrespective of the presence of baryons. This sensitivity may allow …
View article: Feeding plankton to whales: high-redshift supermassive black holes from tiny black hole explosions
Feeding plankton to whales: high-redshift supermassive black holes from tiny black hole explosions Open
Recent observations of the high-redshift universe have uncovered a significant number of active galactic nuclei, implying that supermassive black holes (SMBHs) would have to have been formed at much earlier times than expected. Direct coll…
View article: Testing high scale supersymmetry via second order gravitational waves
Testing high scale supersymmetry via second order gravitational waves Open
Supersymmetry predicts multiple flat directions, some of which carry a net baryon or lepton number. Condensates in such directions form during inflation and later fragment into Q balls, which can become the building blocks of primordial bl…
View article: Defrosting and Blast Freezing Dark Matter
Defrosting and Blast Freezing Dark Matter Open
We show that the present-day dark matter abundance can be produced through a novel mechanism that involves a very rapid thermal freeze-out caused by inhomogeneous heating and successive fast cooling of small fireballs in the early Universe…
View article: Halo formation from Yukawa forces in the very early Universe
Halo formation from Yukawa forces in the very early Universe Open
If long-range attractive forces exist and are stronger than gravity then cosmic halo formation can begin in the radiation-dominated era. We study a simple realization of this effect in a system where dark matter fermions have Yukawa intera…
View article: Fireball baryogenesis from early structure formation due to Yukawa forces
Fireball baryogenesis from early structure formation due to Yukawa forces Open
We show that viable electroweak baryogenesis can be realized without a first-order phase transition if plasma is heated inhomogeneously by nongravitational structure formation in some particle species. Yukawa interactions can mediate relat…
View article: Magnetogenesis from early structure formation due to Yukawa forces
Magnetogenesis from early structure formation due to Yukawa forces Open
Yukawa interactions can mediate relatively long-range attractive forces between fermions in the early universe. Such a globally attractive interaction creates an instability that can result in the growth of structure in the affected specie…
View article: JWST lensed quasar dark matter survey I: Description and First Results
JWST lensed quasar dark matter survey I: Description and First Results Open
The flux ratios of gravitationally lensed quasars provide a powerful probe of the nature of dark matter. Importantly, these ratios are sensitive to small-scale structure, irrespective of the presence of baryons. This sensitivity may allow …
View article: Testing high scale supersymmetry via second order gravitational waves
Testing high scale supersymmetry via second order gravitational waves Open
Supersymmetry predicts multiple flat directions, some of which carry a net baryon or lepton number. Condensates in such directions form during inflation and later fragment into Q-balls, which can become the building blocks of primordial bl…
View article: Structure Formation after Reheating: Supermassive Primordial Black Holes and Fermi Ball Dark Matter
Structure Formation after Reheating: Supermassive Primordial Black Holes and Fermi Ball Dark Matter Open
In the presence of (relatively) long-range forces, structures can form even during the radiation dominated era, leading to compact objects, such as Fermi balls or primordial black holes (PBHs), which can account for all or part of dark mat…
View article: $G$ Objects and primordial black holes
$G$ Objects and primordial black holes Open
We suggest that "$G$ objects" recently discovered in the Galactic Center may be clouds of gas bound by the gravitational field of stellar-mass black holes produced in the interactions of sublunar primordial black holes with neutron stars. …
View article: Constraints on late-forming exploding black holes
Constraints on late-forming exploding black holes Open
Black holes can be produced in collapse of small-scale dark matter structures, which can happen at any time from the early to present-day Universe. Microstructure black holes (MSBHs) can have a wide range of masses. Here, small MSBHs evapo…
View article: Gravitational Waves from Rapid Structure Formation on Microscopic Scales before Matter-Radiation Equality
Gravitational Waves from Rapid Structure Formation on Microscopic Scales before Matter-Radiation Equality Open
The existence of scalar fields can be probed by observations of stochastic gravitational waves. Scalar fields mediate attractive forces, usually stronger than gravity, on the length scales shorter than their Compton wavelengths, which can …
View article: Defrosting and Blast Freezing Dark Matter
Defrosting and Blast Freezing Dark Matter Open
We show that the present-day dark matter abundance can be produced through a novel mechanism that involves a very rapid thermal freeze-out caused by inhomogeneous heating and successive fast cooling of small fireballs in the early Universe…
View article: Explaining the GeV excess with exploding black holes
Explaining the GeV excess with exploding black holes Open
Black holes may form in present-day collapse of microscopic structures of dark matter. We show that, if microstructure black holes (MSBH) with mass $m\sim 10^{13}~g$ are produced, the spectrum of gamma rays from their evaporation agrees re…