Conveners
Cosmic rays
- ILIAS CHOLIS (Johns Hopkins University)
Cosmic rays
- ILIAS CHOLIS (Johns Hopkins University)
Cosmic rays
- nahee park (University of Chicago)
Cosmic rays
- nahee park (University of Chicago)
Cosmic rays
- Michael Sutherland
Cosmic rays
- foteini oikonomou (Penn State University)
Cosmic rays
- foteini oikonomou (Penn State University)
High-energy gamma rays of interstellar origin are produced by the interaction of cosmic-ray (CR) particles with the diffuse gas and radiation fields in the Galaxy. The main features of this emission are well-understood and are reproduced by existing CR propagation models employing 2D Galactocentric cylindrically symmetrical geometry. However, the high-quality data from instruments like the...
The propagation of charged cosmic rays through the Galactic environment influences all aspects of the observation at Earth. Energy spectrum, composition and anisotropy are changed due to deflections in magnetic fields and interactions with the interstellar medium. Today the transport is simulated with different simulation methods either based on the solution of a transport equation...
Cosmic rays propagate in the Milky Way and interact
with the interstellar medium and magnetic fields. These interactions produce emissions that span the electromagnetic spectrum and are an invaluable tool for
understanding the intensities and spectra of cosmic rays in different
regions of the Milky Way. Hence observations of these emissions complement information from cosmic ray...
The Alpha Magnetic Spectrometer (AMS), on the International Space Station (ISS) since May 2011, has acquired the largest number of particles ever measured in space by a single experiment, performing the most precise measurement of galactic cosmic rays (GCR) to-date. The detailed time variation of multiple particle species fluxes measured in the first years of operations, during the ascending...
The Sun shadow can be measured with the IceCube detector and varies in depth corresponding to the magnetic field. Hence, we are given a possibility to understand cosmic ray propagation in the magnetic field of the Sun, for which a sufficiently good modelling is necessary. We investigate the field with its temporal deviations in strength and orientation. In times of low solar activity, the...
The Sun and Moon produce deep deficits in the nearly isotropic flux
of TeV cosmic rays measured at Earth. Observations of these
cosmic-ray deficits, or "shadows," can provide unique measurements
of the solar and Galactic environment. For example, the displacement
of the shadow of the Moon in the geomagnetic field allows for charge
discrimination of high-energy Galactic cosmic...
The Alpha Magnetic Spectrometer (AMS) is a multi-purpose magnetic spectrometer measuring cosmic rays up to TeV energies on the International Space Station (ISS) since 2011. Its precision, large acceptance and ability to identify particle types over a wide energy range during its long duration mission in Space make it unique in astro-particle physics. To date AMS has collected over 100 billion...
Precision measurements by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV are presented based on $3.49 \times 10^5$ antiproton events and $2.42 \times 10^9$ proton events. At $~20$ GV the antiproton-to-proton flux ratio reaches a maximum. Unexpectedly, above 60 GV the antiproton spectral index is...
We present the latest measurement of the combined electron and positron flux in cosmic rays based on the analysis of all the AMS data collected during more than 5 years of operations. The multiple redundant identification of electrons and positrons, and the match of energy measured by the 17 radiation lengths calorimeter and the momentum measured by the tracker in the magnetic field enable us...
Recent direct measurements of cosmic-ray (CR) light nuclei (protons, helium, and lithium) by AMS-02 have shown that the flux of each element has an unexpected hard component above $\sim 300~{\rm GeV}$, and that the spectral indices of those components are almost the same. This implies that there are some primary sources that produce CR lithium nuclei, which have been believed to be produced...
Analysis of anisotropies in the arrival directions of galactic protons, electrons and positrons has been performed by AMS on the International Space Station. An absolute anisotropy measurement has been performed with protons, electrons and positrons. These, together with the results of the anisotropy analysis of the electron to proton, positron to proton, and the positron to electron ratios...
We report the measurements of the fluxes of elementary particles: electrons, positrons, protons, and antiprotons, in the cosmic rays by the AMS experiment. The measured spectra show distinctive features that cannot be explained by ordinary cosmic ray models. In particular, in spite of the different production and propagation properties of protons, antiprotons and positrons, the...
Cosmic Rays escaping the Galaxy exert a force on the interstellar medium directed away from the Galactic disc. If this force is larger than the gravitational pull due to the mass embedded in the Galaxy, then galactic winds may be launched. Such outflows may have important implications for the history of star formation of the host galaxy, and in turn affect in a crucial way the transport of...
Knowledge of the energy dependence of the 3He-to-4He flux ratio (3He/4He) is important in understanding the propagation of cosmic rays. As 3He is assumed to be produced by interactions of heavier nuclei with the interstellar matter, the 3He/4He ratio is a powerful tool for determining the amount of interstellar material traversed by cosmic rays. AMS results are based on 9 million 3He events...
Supernova remnants are known to be the main sources of galactic cosmic-rays.
They could also be a possible explanation for rise of the positron fraction,
if secondary positrons are produced and then accelerated around the supernova shock front. Yet, if secondary positrons are stochastically accelerated in such shocks,
other secondary cosmic ray species will also be accelerated. Using recent...
The role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate galactic winds. Microscopic cosmic ray transport processes are fundamental for determining the efficiency of cosmic ray wind driving. Previous studies focused on...
We evaluated flux of cosmic ray anti-deuteron and anti-Helium3 from secondary astrophysical production.
The production cross section at proton-proton collision is one of the most important input parameter to determine the secondary cosmic ray flux. However, composite (anti-)nuclei production cross section is very small and the cross section data at collider experiments is quite limited. That...
Measurements of the Geminga and B0656+14 pulsars by HAWC and Milagro indicate that these objects generate significant fluxes of very high-energy electrons. From the very high-energy gamma-ray intensity and spectrum of these pulsars, one can calculate their expected contributions to the local cosmic-ray positron spectrum. From these considerations, we find that pulsars produce a flux of...
The CALorimetric Electron Telescope (CALET) space experiment, which has been developed by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics mission to be installed on the International Space Station (ISS). The primary goals of the CALET mission include investigating possible nearby sources of high energy electrons, studying the details of galactic...
The objectives of the Pierre Auger Observatory are to probe the origin and characteristics of cosmic rays above $10^{17}$ eV and to study the interactions of these, the most energetic particles observed in nature. The Observatory design features an array of water Cherenkov stations deployed over a surface of $3000$ km$^2$ overlooked by fluorescence telescopes. This design and a sophisticated...
The Telescope Array (TA) measures the properties of ultra high energy cosmic ray (UHECR) induced extensive air showers. TA employs a hybrid detector comprised of a large surface array of scintillator detectors overlooked by three fluorescence telescopes stations. The TA Low Energy extension (TALE) detector has operated as a monocular Cherenkov/fluorescence detector for nearly three years, and...
The flux of cosmic rays is observed at the Pierre Auger Observatory spanning almost three decades in energy. This energy range is possible by combining the measurements from the nested 1500 m and 750 m surface detector arrays. The energy scale relies on the almost calorimetric energy measurements performed with Auger's fluorescence detectors. With a total exposure of about 52000 [km^2 sr yr]...
The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a design concept for the next generation of Ultra-High-Energy Cosmic Ray (UHECR) observatories, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the highest energy cosmic rays. In the FAST design, a large field of view is covered by a few pixels at the focal plane of an...
Over the last 15 years, we have achieved a detailed understanding of the physics of radio emission from extensive air showers, and have consequently succeeded in developing sophisticated detection schemes and analysis approaches. In particular, we have demonstrated that the important air-shower parameters arrival direction, particle energy and depth of shower maximum can be reconstructed...
We demonstrate here the ability of TREND, a self-triggered radio array, to autonomously detect and identify air showers induced by cosmic rays. TREND (Tianshan Radio Experiment for Neutrino Detection) is an array of 50 dipolar antennas, deployed over a total area of 1.5km² on the site of the 21CMA radio interferometer in the radio-quiet Tianshan mountains (China), and running between 2009 and...
The Interstellar Boundary Explorer (IBEX) is an Earth-orbiting spacecraft equipped with two single-pixel cameras that detect neutral atoms produced by the interaction of the solar wind (SW) with the very local interstellar medium (VLISM), as well as neutral atoms flowing in from the VLISM itself. After its launch in 2009, IBEX discovered the unexpected existence of the “ribbon,” a nearly...
In 2015, the HAWC Observatory was completed and began operation as the most sensitive TeV cosmic-ray detector in the Northern Hemisphere. Since that time, we have recorded over 1 trillion cosmic-ray air showers, designed a likelihood-based cosmic-ray energy reconstruction, and implemented a new minimally-biased method for reconstructing all-sky anisotropy. These three advances in statistics,...
Although cosmic rays are nearly isotropic, ground-based arrays sensitive to TeV cosmic rays have measured a small anisotropy in right ascension. Understanding the morphology and energy dependence of this anisotropy can yield insight into cosmic-ray sources and propagation in the local magnetic field. The Fermi Large Area Telescope (LAT) is optimized for gamma-ray measurements, but it records...
Even when ultrahigh-energy (E > 10^10 GeV) cosmic rays (UHECRs) are heavy nuclei (with nuclear charge Z) as indicated by existing data, the pointing of cosmic rays to the nearest extragalactic sources (distance D) at highest energies remains expected, because the bending of the cosmic ray goes as BZD/E (B is the extra-galactic magnetic field). In addition, the acceleration capability of the...
The arrival directions of multi-TeV cosmic rays show significant anisotropies at large and small angular scales. I will argue that these features can be understood from standard cosmic ray diffusion. It is well-known that a large-scale dipole anisotropy is expected from a cosmic ray density gradient following the distribution of Galactic sources. However, the observed anisotropy depends on...
The shape of the large-scale cosmic-ray (CR) anisotropy depends on (and therefore contains information on) the local interstellar turbulence within ~ 10 pc from Earth. We calculate the TeV-PeV CR anisotropies predicted for a range of Goldreich-Sridhar (GS) and isotropic models of interstellar turbulence, and compare them with IceTop and IceCube data. The narrow deficits in the 400TeV and 2PeV...
Tidal disruption events (TDEs) by supermassive or intermediate mass black holes have been suggested as candidate sources of ultrahigh-energy cosmic rays (UHECRs) and high-energy neutrinos. Motivated by the recent measurements from the Pierre Auger Observatory, which indicates a metal-rich cosmic-ray composition at ultrahigh energies, we investigate the fate of UHECR nuclei loaded in TDE jets....
There is tentative evidence for an ultra-high-energy cosmic-ray (UHECR) “hot spot” coming from the direction of Centaurus A and also evidence for another hot spot that might be associated with the M81 group. Although the evidence is not firmly established, it is not all unreasonable, given the energetics and the physical conditions in Cen A and in various galaxies in the M81 group, that these...
The various coherent and turbulent components of the Galactic magnetic field have sufficiently high field strengths to alter the arrival distributions of cosmic rays, including those at ultra-high energies.
I will highlight the results of a study considering a realistic GMF model including a persistent turbulent component, and rigidities $R \equiv E / Z \geq 10^{18}$ V reaching sufficiently...
The sources of the highest-energy particles in the Universe remain a still-unresolved mystery. The reason is that charged-particle astronomy is severely complicated by magnetic deflections, which, for sources in the local Universe, are dominated by the effect of the Galactic magnetic field. I will discuss the PHAESTOS project - a radically new approach to identifying individual sources of...
Local Radio galaxies (RGs) like Centaurus A are intensively discussed as the source of the observed Cosmic Rays above 3 EeV (UHECRs).
In this talk a first systematic study is presented where all observational features of the UHECRs, i.e. the energy spectrum, the chemical composition and the arrival directions, are used to draw severe constraints on the UHECR contribution from the local RGs (up...
We propose an astrophysical scenario for ultrahigh-energy cosmic-ray production, in which galactic cosmic rays are reaccelerated by kiloparsec-scale jets in active galactic nuclei. We perform Monte Carlo simulations of transrelativistic shear acceleration dedicated to a jet-cocoon system of active galactic nuclei. A certain fraction of galactic cosmic rays in a halo is entrained, and...
