A5074726619- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Gamma-ray bursts and supernovae
- Particle physics theoretical and experimental studies
- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Particle Detector Development and Performance
- Radio Astronomy Observations and Technology
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Stellar, planetary, and galactic studies
- Radiation Detection and Scintillator Technologies
- Scientific Research and Discoveries
- Atomic and Subatomic Physics Research
- Astro and Planetary Science
- Nuclear Physics and Applications
- Astrophysical Phenomena and Observations
- CCD and CMOS Imaging Sensors
- Astronomical Observations and Instrumentation
- Geophysics and Gravity Measurements
- Particle Accelerators and Free-Electron Lasers
- Solar and Space Plasma Dynamics
- Advanced X-ray Imaging Techniques
- Superconducting and THz Device Technology
Kavli Institute for the Physics and Mathematics of the Universe
2009-2025
The University of Tokyo
2007-2025
Virginia Tech
2016-2025
Keio University
2025
Campbell Collaboration
2022
Australian National University
2021
University of Amsterdam
2021
Johns Hopkins University
2021
The Ohio State University
2009-2019
Istituto Nazionale di Fisica Nucleare, Sezione di Torino
2017
On the strength of a double Nobel prize winning experiment (Super)Kamiokande and an extremely successful long baseline neutrino programme, third generation Water Cherenkov detector, Hyper-Kamiokande, is being developed by international collaboration as leading worldwide based in Japan. The Hyper-Kamiokande detector will be hosted Tochibora mine, about 295 km away from J-PARC proton accelerator research complex Tokai, currently existing steadily upgraded to reach MW beam start experiment. A...
We construct empirical models of the diffuse gamma-ray background toward Galactic Center. Including all known point sources and a template emission associated with interactions cosmic rays molecular gas, we show that extended observed previously in Fermi Large Area Telescope data Center is detected at high significance for permutations model components. However, find fluxes spectra our change significantly depending on model. In particular, spectrum central Sgr A$^\ast$ source less steep...
We show that the canonical oscillation-based (non-resonant) production of sterile neutrino dark matter is inconsistent at $>99$% confidence with observations galaxies in Local Group. set lower limits on non-resonant mass $2.5$ keV (equivalent to $0.7$ thermal mass) using phase-space densities derived for dwarf satellite Milky Way, as well $8.8$ $1.8$ based subhalo counts $N$-body simulations M 31 analogues. Combined improved upper from significantly deeper X-ray data full consideration...
Hyper-Kamiokande will be a next-generation underground water Cherenkov detector with total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that Super-Kamiokande. One the main goals is study |$CP$| asymmetry in lepton sector using accelerator neutrino and anti-neutrino beams. In this paper, physics potential long-baseline experiment beam from J-PARC proton synchrotron presented. The analysis uses framework systematic uncertainties derived ongoing...
Hyper-Kamiokande consists of two identical water-Cherenkov detectors total 520~kt with the first one in Japan at 295~km from J-PARC neutrino beam 2.5$^{\textrm{o}}$ Off-Axis Angles (OAAs), and second possibly Korea a later stage. Having detector would benefit almost all areas oscillation physics mainly due to longer baselines. There are several candidate sites baselines 1,000$\sim$1,300~km OAAs 1$^{\textrm{o}}$$\sim$3$^{\textrm{o}}$. We conducted sensitivity studies on for detector, either...
We present two complementary NuSTAR x-ray searches for keV-scale dark matter decaying to mono-energetic photons in the Milky Way halo. In first, we utilize known intensity pattern of unfocused stray light across detector planes -- dominant source from diffuse sources separate astrophysical emission internal instrument backgrounds using ${\sim}$7-Ms/detector deep blank-sky exposures. second, an updated parametric model full background, allowing us leverage statistical power independent...
Energetic cosmic rays scatter off the neutrino background throughout history of Universe, yielding a diffuse flux relic neutrinos boosted to high energies. We calculate this under different assumptions cosmic-ray spectral slope and redshift evolution. The nonobservation with current high-energy experiments already excludes an average overdensity larger than <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"...
We identify a "supernova rate problem": the measured cosmic core-collapse supernova is factor of ~ 2 smaller (with significance sigma) than that predicted from massive-star formation rate. The comparison critical for topics galaxy evolution and enrichment to abundance neutron stars black holes. systematically explore possible resolutions. accuracy precision star data conversion are well supported, proposed changes would have far-reaching consequences. dominant effect likely many supernovae...
The diffuse supernova neutrino background (DSNB) provides an immediate opportunity to study the emission of MeV thermal neutrinos from core-collapse supernovae. DSNB is a powerful probe stellar and physics, provided that rate large enough its uncertainty small enough. To assess important physics enabled by DSNB, we start with cosmic star formation history Hopkins Beacom (2006) confirm normalization evolution cross-checks rate, extragalactic light, mass density. We find sufficient...
In the indirect detection of dark matter through its annihilation products, signals depend on square density, making precise knowledge distribution in Universe critical for robust predictions. Many studies have focused regions where density is greatest, e.g., galactic center, as well cosmic signal arising from all halos Universe. We focus whole Milky Way halo; this less sensitive to uncertainties distribution, and especially flatter profiles, halo larger than signal. illustrate by...
We use a combined 1.2 Ms of NuSTAR observations M31 to search for x-ray lines from sterile neutrino dark matter decay. For the first time in analysis, we consistently take into account signal contribution both focused and unfocused fields view. also reduce modeling systematic uncertainty by performing spectral fits each observation individually statistically combining results, instead stacking spectra. find no evidence unknown lines, thus derive limits on parameters. Our results place...
We use NuSTAR observations of the Galactic center to search for x-ray lines from radiative decay sterile neutrino dark matter. Finding no evidence unknown lines, we set limits on mass and mixing angle. In most range 10--50 keV, these are now strongest limits, at some masses improving upon previous by a factor $\ensuremath{\sim}10$. $\ensuremath{\nu}\mathrm{MSM}$ framework, where additional constraints matter production structure formation apply, allowed parameter space is reduced more than...
The next Galactic supernova is expected to bring great opportunities for the direct detection of gravitational waves (GW), full flavor neutrinos, and multi-wavelength photons. To maximize science return from such a rare event, it essential have established classes possible situations preparations appropriate observations. this end, we use long-term numerical simulation core-collapse (CCSN) 17 solar-mass red supergiant progenitor self-consistently model multi-messenger signals in GW,...
Abstract The next core-collapse supernova in the Milky Way or its satellites will represent a once-in-a-generation opportunity to obtain detailed information about explosion of star and provide significant scientific insight for variety fields because extreme conditions found within. Supernovae our galaxy are not only rare on human timescale but also happen at unscheduled times, so it is crucial be ready use all available instruments capture possible from event. first indication potential...
We analyze two dedicated NuSTAR observations with exposure ${\sim}190$ ks located ${\sim}10^\circ$ from the Galactic plane, one above and other below, to search for x-ray lines radiative decay of sterile-neutrino dark matter. These fields were chosen minimize astrophysical backgrounds while remaining near densest region matter halo. find no evidence anomalous in energy range 5--20 keV, corresponding sterile neutrino masses 10--40 keV. Interpreted context neutrinos produced via mixing, these...
The sensitivity of current and future neutrino detectors like Super-Kamiokande (SK), JUNO, Hyper-Kamiokande (HK), DUNE is expected to allow for the detection diffuse supernova background (DSNB). However, DSNB model ingredients core-collapse (CCSN) rate, emission spectra, fraction failed supernovae are not precisely known. We quantify uncertainty on each these by (i) compiling a large database recent star formation rate density measurements, (ii) combining from long-term axisymmetric CCSNe...
The gamma-ray Fermi-LAT Galactic centre excess (GCE) has puzzled scientists for over 15 years. Despite ongoing debates about its properties, and especially spatial distribution, nature remains elusive. We scrutinize how the estimated morphology of this depends on models diffuse emission, focusing particularly extent to which plane point sources are masked. Our main aim is compare a spherically symmetric - potentially arising from annihilation dark matter (DM) particles with boxy expected if...
The IceCube neutrino observatory has detected two cascade events with energies near 1 PeV [A. Ishihara Proceedings of Neutrino 2012 Conference, http://neu2012.kek.jp/index.html; M. Aartsen et al. (IceCube Collaboration) Phys. Rev. Lett. 111, 021103 (2013)]. Without invoking new physics, we analyze the source these neutrinos. We show that atmospheric conventional neutrinos and cosmogenic (those produced in propagation ultra-high-energy cosmic rays) are strongly disfavored. For prompt or a...
Hyper-Kamiokande will be a next generation underground water Cherenkov detector with total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that Super-Kamiokande. One the main goals is study $CP$ asymmetry in lepton sector using accelerator neutrino and anti-neutrino beams. In this document, physics potential long baseline experiment beam from J-PARC proton synchrotron presented. The analysis has been updated previous Letter Intent [K. Abe et al.,...
Recent results from the Pierre Auger Collaboration have shown that composition of ultrahigh-energy cosmic rays (UHECRs) becomes gradually heavier with increasing energy. Although gamma-ray bursts (GRBs) been promising sources UHECRs, it is still unclear whether they can account for because their unknown nuclear ejected UHECRs. In this work, we revisit possibility low-luminosity GRBs (LL GRBs) act as UHECR nuclei and give new predictions based on intrajet models considering progenitor...
Abstract Mapping supernovae to their progenitors is fundamental understanding the collapse of massive stars. We investigate red supergiant problem, which concerns why supergiants with masses ∼16–30 M⊙ have not been identified as Type IIP supernovae, and supernova rate observed cosmic smaller than star formation rate. find key physics solving these in compactness parameter, characterizes density structure progenitor. If stars above ξ2.5 ∼ 0.2 fail produce canonical (i) mass range 16–30...
This year marks the thirtieth anniversary of only supernova from which we have detected neutrinos - SN 1987A. The twenty or so that were mined to great depth in order determine events occurred explosion and place limits upon all manner neutrino properties. Since 1987 scale sensitivity detectors capable identifying a Galactic grown considerably current generation are detecting ten thousand for at Center. Next will increase yield by another magnitude. Simultaneous with growth detection...
The extended excess toward the Galactic Center (GC) in gamma rays inferred from Fermi-LAT observations has been interpreted as being due to dark matter (DM) annihilation. Here, we perform new likelihood analyses of GC and show that, when including templates for stellar galactic nuclear bulges, shows no significant detection a DM annihilation template, even after generous variations diffuse emission models wide range halo profiles. We include with combinations three-dimensional inverse...