Conveners
CR: CR1 : Galactic Cosmic-rays I
- Katherine Rawlins (University of Alaska Anchorage)
CR: CR2 : UHECR measurements with Radio and future observatories
- Eiji Kido (Institute for Cosmic Ray Research, University of Tokyo)
CR: CR3 : Modeling of Galactic Cosmic-Rays
- Susumu Inoue (Chiba University / ICRR, University of Tokyo)
CR: CR4 : Cosmic-Ray Air-Showers
- Munehiro OHNISHI (ICRR, Univ. of Tokyo)
CR: CR5 : Magnetic Field
- Aleksandr Stuzhin (Shandong Institute of Advanced Technology)
CR: CR6 : UHECR measurements
- Shigeru Yoshida (International Center for Hadron Astrophysics, Chiba University)
CR: CR7 : Galactic Cosmic-Rays II
- Tsunefumi Mizuno (Hiroshima University)
Analysis of anisotropy of the arrival directions of galactic positrons, electrons and protons has been performed with the Alpha Magnetic Spectrometer on the International Space Station. This measurement allows to differentiate between point-like and diffuse sources of cosmic rays for the understanding of the origin of high energy positrons or the hardening in the proton flux. The AMS results...
There is an observed anisotropy in the arrival direction distribution of cosmic rays in the TeV-PeV regime, with variations on the scale of one part in a thousand. While the origin of this anisotropy is an open question, a possible factor is cosmic-ray interactions with interstellar and heliospheric magnetic fields. These magnetic fields may change over time - for example, due to changes in...
In this talk we will cover major cosmic ray and gamma ray results of the DAMPE mission after the first 10 years of operation. We will highlight the recent discovery of a universal charge-dependent structure in all primary cosmic rays, from hydrogen to iron, appearing at 14 TV rigidity. We talk about the recent progress in cosmic ray analysis at multi-TeV frontier, measurements of individual...
The TALE infill experiment is further low-energy extension of Telescope Array Low-energy Extension (TALE), aiming to observe cosmic rays with energies from 1 PeV to 100 PeV. The goal of this project is revealing โkneeโ structure in the energy spectrum. 50 surface detectors (SDs) are deployed with 100-m spacing to observe this energy region. The experiment began operation in November 2023 and...
The TA Low-energy Extension (TALE) experiment extends the reach of the TA experiment on the low-energy side to below $10^{16}\,$eV. A primary objective of TALE is to study the transition from galactic to extragalactic cosmic rays. The TALE detector is a hybrid observatory composed of fluorescence telescopes and a surface detector array of scintillation counters. The surface detectors are...
The CALorimetric Electron Telescope (CALET) has been in operation on the International Space Station since October 2015, providing more than a decade of continuous and stable observations of high-energy cosmic rays and gamma rays. The mission aims to search for nearby cosmic-ray sources and dark matter signatures through precise measurements of cosmic-ray electrons, and to investigate...
Earth-skimming tau neutrinos with energies above ~10 PeV can convert to tau leptons and decay in the atmosphere, initiating upward-going extensive air showers. POEMMA Balloon with Radio (PBR) is designed to measure these showers via a novel hybrid of optical Cherenkov and low-frequency radio measurements. The ability to point the detector above and below the limb will allow the observation...
The origin of ultra-high-energy cosmic rays (UHECRs) is one of the most intriguing mysteries in astroparticle physics and high-energy physics. With an ability to select events by the rigidity $(E/Z)$, arrival directions of UHECRs can be exploited to probe the most extremely energetic phenomena in the universe. The Global Cosmic Ray Observatory (GCOS) is a proposed next-generation observatory...
We present a comprehensive study of synchrotron X-ray and gamma-ray emission (10 keV to 1 GeV) from extensive air showers (EAS) induced by ultra-high energy cosmic rays and Earth-skimming tau neutrinos, as a novel and complementary hybrid detection channel for future high-altitude observatories.
Unlike Cherenkov or fluorescence emission, geo-synchrotron radiation is dominated by shower...
To detect ultra-high energy neutrinos, experiments such as the Askaryan Radio Array (ARA) and the Radio Neutrino Observatory in Greenland (RNO-G) rely on radio antennas deployed in ice to detect particle cascades. This requires characterizing the in-ice radio emission from cosmic rays, which constitutes both a calibration source and a major background in the search for neutrinos. The accurate...
The Radar Echo Telescope for Cosmic Rays (RET-CR) is a pathfinder experiment for a future neutrino telescope, using cosmic rays as an in-situ test beam as a validation of the radar echo technique. The buried radar system monitors for echoes off high-energy cosmic-ray induced in-ice cascades. This work presents progress towards a future sub-threshold analysis of the RET dataset. The RET...
NUSES is a space mission, equipped with two scientific payloads named, Zirรจ and Terzina. Zirรจ is a hybrid detector comprising a fiber tracker, plastic scintillator and a segmented GAGG calorimeter, designed to measure the cosmic ray composition (electron, proton and lighter nuclei) from few MeV to 300 MeV, while simultaneously detecting gamma ray transients up to 50 MeV. Terzina employs an...
Globular clusters (GCs) are long-lived relics of galaxy assembly and retain important information about merger history, chemical enrichment, and the build-up of galactic bulges and halos. We investigate the prospect that their high-energy emission may provide a new, complementary way to probe this evolution. In our scenario, millisecond pulsars (MSPs) in GCs power persistent GeV emission,...
The Fermi bubbles are giant bipolar structures in the Galactic halo. Their formation mechanism and the origin of their hard gamma-ray spectrum remain unclear. Most interpretations have regarded the bubbles as evidence of past Galactic center activity, with leptonic models proposed to explain the hard gamma-ray emission. More recently, some scenarios suggest that the FBs arise naturally from...
Most ~1-10 GeV hadronic cosmic rays accelerated in star-forming galaxies will eventually escape the relatively dense ISM gas and leak into the circumgalactic medium (CGM). What happens to them thereafter and do they do anything important in this low density environment? I will show that these CRs are, in fact, important: using a new semi-analytic model we have developed over the last few years...
The X-ray binary system SS 433 launches mildly relativistic jets that extend over several tens of parsecs. The nonthermal emission detected from the jets is best explained by multi-TeV electrons producing X-ray synchrotron and inverse Compton emission of TeV gamma rays. The LHAASO detection of ultra-high-energy ($>$100 TeV) gamma-ray emission further establishes SS 433 as a potential PeVatron....
Microquasars are primary candidates for Galactic PeVatrons, yet their collective contribution to the cosmic ray (CR) "knee" remains poorly understood. At PeV energies, local CR measurements are strongly influenced by individual Galactic PeVatrons and the Galactic magnetic field.
In this talk, we model the temporal and spatial distribution of source populations and transport Galactic CRs...
Calibrating the energy scale of surface detector arrays using fluorescence detector data is a primary source of systematic uncertainty at ultra-high-energy cosmic ray observatories. Standard procedures provide point estimates of the calibration function with no associated uncertainty. We present a hierarchical Bayesian model that introduces the true event energy as a latent variable, allowing...
Fluorescence detector Array of Single-pixel Telescopes (FAST) aims to achieve high-statistics observations of ultra-high-energy cosmic rays by deploying a large number of fluorescence telescopes over a wide area for next-generation cosmic-ray experiments. Total seven FAST prototypes are currently installed and operated at sites of the Telescope Array experiment and the Pierre Auger...
Cosmic-ray chemical composition measurements are important for elucidating the origin of cosmic rays within the galaxy. The iron cosmic-ray spectrum in the TeV band is not yet well-characterized because of large statistical uncertainties, necessitating high-precision measurements in this energy range. TeV iron cosmic-rays can be observed with imaging atmospheric Cherenkov telescope by...
The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a next-generation experiment designed for observing ultra-high-energy cosmic rays (UHECRs). Compared to conventional fluorescence detector, FAST features a compact and low-cost design by reducing the number of photomultiplier tubes. This design allows for the deployment of a large number of telescopes, aiming to achieve an...
Iron cosmic rays constitute the most common heavy nuclei at energies above 1โฏTeV and are thought to arise mainly from astrophysical environments. Accurate determinations of their energy spectrum offer essential clues about the origin, acceleration, and transport of cosmic rays. Recent measurements by satelliteโbased instruments have shown unexpected spectral features in the GeVโTeV domain;...
Measurements of long-lived isotopes in meteoritic data indicate the flux of Galactic cosmic rays (GCRs) has been constant for several Myr, however these measurements may be uncertain by 30% or more, due to confounding factors such as solar and geomagnetic modulation of the GCR flux. $^{14}$C produced in situ by interactions between cosmic ray muons and $^{16}$O atoms in ice can serve as a new...
Large-scale intergalactic magnetic fields (IGMFs) may comprise both galactic and cosmogenic components, which can be probed via observations of delayed $\gamma$-ray emission from electromagnetic cascades initiated by the highest-energy photons emitted by distant sources. These components can, in principle, be distinguished through their redshift evolution; however, observational evidence for...
A cosmological origin of magnetic fields in large-scale structures implies the existence of a weak intergalactic magnetic field (IGMF) in cosmic voids, which remains undetected. High-energy gamma rays from distant transients, provide an indirect probe: during propagation, TeV ฮณ-rays initiate electromagnetic cascades whose charged components are deflected by the IGMF, producing a characteristic...
The extragalactic background light (EBL) encodes the integrated emission history of all extragalactic sources and serves as a key probe of star formation and galaxy evolution. Gamma-ray observations offer a unique method to measure the EBL through the energy-dependent attenuation of blazar spectra via pair production with EBL photons. We present complementary EBL measurements spanning GeV to...
Solar disk gamma rays, theorized to originate from hadronic galactic cosmic ray interactions, exhibit many puzzling features. Above 0.1 giga-electronvolts (GeV), these features include high flux and anti-correlation with the solar activity cycle. Between 10 and 50 GeV, it also displays an unexpected time- and energy- dependent morphology. A key question is how solar magnetic fields could...
We present a simulation study of Earth albedo gamma-ray intensity as observed by the Fermi Large Area Telescope (LAT), and its dependence on geomagnetic cutoff rigidity of cosmic ray proton. We perform Monte Carlo simulations of particle interactions in the Earthโs atmosphere using GEANT4, including the effects of the geomagnetic field. Our simulation result confirm the correlation, previously...
On their way to Earth, cosmic rays are blocked by the Sun and Moon, leading to a relative deficit of detectable cosmic rays at Earth, the cosmic ray Sun/Moon shadow. With the IceCube Neutrino Observatory, atmospheric muons are detected that are produced when cosmic rays interact with the Earthโs atmosphere. While the Moon shadow serves as an absolute pointing calibration, the Sun shadow depth...
Due to their size and underdense structures, cosmic voids offer enhanced sensitivity to the properties of dark energy. We show that the Type 3 interacting dark energy model parameters have significant effects on the radial velocity and velocity dispersion of these voids, though the effects of the momentum coupling $\beta$ ($<0$ ) and scalar field potential parameter $\lambda$ on the radial...
The energy spectrum of ultra-high-energy cosmic rays (UHECRs) above 2.5$\,$EeV is measured over the declination range $-90^\circ$ to $+44.8^\circ$ using 310,000 events from the Pierre Auger Observatory, corresponding to an exposure of $(104{,}900 \pm 3{,}100)\,\mathrm{km}^2\,\mathrm{sr}\,\mathrm{yr}$. The energy spectrum is studied as a function of declination to investigate possible...
The Telescope Array (TA) is the largest cosmic-ray observatory in the Northern Hemisphere. With the main goal of determining the origin of cosmic rays, it is designed to measure the properties of cosmic rays over a wide energy range. Together with its low-energy extension, TALE, TA observes cosmic-ray-induced extensive air showers from 2ร10^15 to 2ร10^20โฏeV in hybrid mode, employing a surface...
Ultra-high-energy cosmic rays (UHECRs) are the most energetic charged particles observed in nature, but their sources and propagation processes are still not fully understood. The Telescope Array (TA) experiment, the largest UHECR observatory in the Northern Hemisphere, has achieved high-precision measurements of the cosmic ray energy spectrum through stable long-term operation and efficient...
The Pierre Auger Observatory has been measuring extensive air showers produced by ultra-high-energy cosmic rays (UHECRs) for over two decades. While significant progress in this field has been made, the sources, acceleration mechanisms, and hadronic interactions at these energies still remain poorly understood. A key property for constraining these open questions is the mass composition of the...
Ultra-high-energy cosmic rays (E > $10^{18}$ eV) are the most energetic particles in the Universe and, as such, provide a unique opportunity to probe hadronic interactions at energies beyond those reached at the LHC. Due to their extremely low flux, these cosmic rays can only be studied indirectly through extensive air showers (EAS), cascades of secondary particles produced when a primary...
Accurately modeling the atmospheric lepton fluxes plays a crucial role for astrophysical neutrino search, neutrino oscillations studies, probing hadronic interaction models, beyond-standard-model searches, and tools such as muon tomography. In this talk, I present the latest update of the flux modeling code MCEq (Matrix Cascade Equations), featuring an updated particle yield and cross-section...
We report a measurement of the all-particle cosmic-ray energy spectrum with the ALPAQUITA array, the prototype of the ALPACA experiment, located at an altitude of 4,740 m on Mount Chacaltaya in Bolivia. The array consists of 97 scintillation detectors deployed on a 15 m grid. Using approximately 240 days of data, we measure the cosmic-ray flux in the energy range from 10 TeV to 300 TeV. This...
The energy spectrum and arrival direction anisotropy of high-energy
cosmic-ray electrons above 1 TeV serve as crucial probes for identifying
nearby acceleration sources. The Tibet AS$\gamma$ experiment, an air
shower array located at an altitude of 4,300 m, aims to observe cosmic-
ray electrons in the energy region above 10 TeV.
In this study, we developed an energy determination method...
We report the properties of cosmic ray nuclei from protons to nickel (Z=1--20, 26, and 28) in the rigidity range from 2 GV to 3 TV
collected by the Alpha Magnetic Spectrometer (AMS) on the International Space Station during 15 years of operation. AMS is the
only magnetic spectrometer in space. Unexpectedly, the twenty-one element measured by AMS, from He to Ca and Fe, Ni can be...
Latest results by AMS on the fluxes and flux ratios of charged elementary particles in the absolute rigidity range from 1 up to 2000 GV
reveal unique properties of cosmic charged elementary particles. The positron flux in the TeV region exhibits complex energy dependence.
It is described by the sum of a term associated with the positrons produced in the collision of cosmic rays, which...
The Alpha Magnetic Spectrometer (AMS-02) is a high-energy particle detector designed to measure different species of galactic cosmic rays in the GV to TV rigidity range with unprecedented accuracy, in order to study fundamental physics in space. Since its installation on the International Space Station in May 2011, AMS has been measuring hourly, daily, monthly, and yearly cosmic radiation over...
The origin of galactic cosmic rays (CRs) and the nature of their acceleration up to PeV energies remains one of the central open questions in astroparticle physics. Precise measurements of the CR proton spectrum in the multi-TeV to PeV range are essential to identify spectral features linked to acceleration and propagation processes, yet direct observations are limited to a few hundreds of...
Highly energetic astrophysical processes are studied through measurements of cosmic radiation, yet the mechanisms responsible for accelerating particles to high energies remain unconfirmed. New isotope measurements of long-lived unstable nuclei can provide unique constraints on Galactic cosmic-ray propagation and the size of the Milky Way halo. In particular, the clock isotopes 10Be...
At the highest energies, the prompt atmospheric neutrino flux from charmed-hadron decays contributes to the background in astrophysical neutrino source searches, but remains uncertain due to sparse constraints on forward heavy-flavor production and differences among hadronic interaction models. Atmospheric muons probe related air-shower physics and complement neutrino measurements: prompt...
In the standard Galactic cosmic-ray (CR) paradigm, protons are accelerated up to $\sim 1$~PeV by Galactic sources. While supernova remnants (SNRs) have been traditionally considered as the primary accelerators, recent observations by LHAASO and HAWC have detected very-high-energy (VHE) gamma rays exceeding 100~TeV from several microquasars, suggesting that these X-ray binaries can accelerate...
We propose that the observed spectral hardening in Galactic cosmic ray fluxes is governed by macroscopic Galactic outflows, such as the eROSITA bubbles, rather than microphysical variations in their scattering properties. Employing a phenomenological transport model, we show that an advective outflow boundary naturally reproduces the $300\,$GV hardening in secondary-to-primary ratios. Global...
