Cosmic ray physics

Cosmic ray physics
Name	Cosmic ray physics
Field	Astroparticle physics
Related	Astrophysics; Particle physics; Space physics
Notable	Victor Hess; Pierre Auger; Bruno Rossi; Eugene Parker; John Linsley

Contents

Cosmic ray physics Cosmic ray physics is the study of high-energy charged particles originating outside Earth's atmosphere and their production, propagation, interactions, and detection. It connects observational programs led by institutions such as CERN, NASA, ESA, Max Planck Institute for Physics, and Los Alamos National Laboratory with theoretical work from researchers affiliated with Princeton University, MIT, Caltech, University of Chicago, and University of Tokyo. The field interfaces with experiments including the Pierre Auger Observatory, IceCube Neutrino Observatory, Fermi Gamma-ray Space Telescope, AMS-02, and KASCADE-Grande.

Overview and history

Early discovery traces to balloon flights by Victor Hess and contemporaneous measurements at Mount Wilson Observatory and institutions like Imperial College London and University of Manchester. Developments in the 20th century involved contributions from Bruno Rossi, Patrick Blackett, and Robert Millikan at laboratories including University of Cambridge and Columbia University. The discovery of extensive air showers by Pierre Auger and later measurements by John Linsley at Volcano Ranch drove modern large-array projects such as the Pierre Auger Observatory and the Telescope Array Project. Theoretical advances have been shaped by work from Enrico Fermi, Subrahmanyan Chandrasekhar, Eugene Parker, and groups at Princeton Plasma Physics Laboratory and Kavli Institute for the Physics and Mathematics of the Universe.

Primary sources include acceleration sites near Supernova Remnants exemplified by SN 1006, compact objects like Pulsar Wind Nebulae such as the Crab Nebula, active galactic nuclei in galaxies like M87, and transient events like Gamma-ray Bursts observed by Swift (satellite). Composition studies rely on comparisons to solar system material from missions like Voyager 1 and Ulysses and laboratory analyses performed at Lawrence Berkeley National Laboratory and Argonne National Laboratory. Measurements identify protons, helium nuclei, heavier nuclei such as iron linked to remnants in Cassiopeia A, electrons associated with sources like Vela, and secondary antimatter components detected by AMS-02 and instruments on International Space Station. Radioisotopes such as beryllium-10 provide links to chronology work at Carnegie Institution for Science and isotope labs at Lawrence Livermore National Laboratory.

Propagation studies model diffusion in galactic magnetic fields characterized by data from Planck (spacecraft) and magnetohydrodynamic theory from research groups at Johns Hopkins University and University of Colorado Boulder. Interactions include spallation in the interstellar medium informed by observations from Chandra X-ray Observatory and scattering in heliospheric environments monitored by ACE (spacecraft). Processes such as pion production connect to neutrino detections at IceCube Neutrino Observatory and gamma-ray signatures seen by Fermi Gamma-ray Space Telescope and H.E.S.S.. Transport equations developed at Max Planck Institute for Astrophysics and numerical tools from Los Alamos National Laboratory underpin cosmic-ray propagation codes used across Princeton University and Harvard-Smithsonian Center for Astrophysics.

Detection spans ground arrays like the Pierre Auger Observatory and Telescope Array Project, balloon programs tied to Columbia Scientific Balloon Facility and experiments such as BESS (balloon), satellite detectors including AMS-02 on the International Space Station and the Fermi Gamma-ray Space Telescope, and neutrino telescopes such as IceCube Neutrino Observatory at South Pole Station. Radio detection efforts involve collaborations at LOFAR and Aperture Array facilities related to ASTRON and Netherlands Institute for Radio Astronomy. Cherenkov telescopes such as VERITAS, MAGIC, and H.E.S.S. probe air-shower photons, while fluorescence detectors developed by teams at University of Leeds and University of Utah record atmospheric nitrogen fluorescence. Accelerator-based tests utilize beamlines at CERN and SLAC National Accelerator Laboratory.

The all-particle energy spectrum exhibits structures known as the "knee" and the "ankle," first characterized by arrays like KASCADE and confirmed by HiRes and Auger Collaboration. Ultra-high-energy events above the Greisen–Zatsepin–Kuzmin limit were reported by detectors at AGASA and later studied by Pierre Auger Observatory and Telescope Array Project. Spectral measurements from Balloon-borne Experiment with a Superconducting Spectrometer and CREAM complement satellite-derived spectra from AMS-02 and PAMELA; interpretation uses models produced by research teams at University of Minnesota and Rutgers University. Features correlate with source populations studied at VLA, Hubble Space Telescope, and observatories like ALMA.

Acceleration frameworks include diffusive shock acceleration formulated by Enrico Fermi and developed at centers such as Princeton University and University of California, Berkeley. Magnetic reconnection scenarios are studied in contexts like the Solar flare environment observed by SOHO (spacecraft) and Solar Dynamics Observatory with theoretical input from MIT and Stanford University. Relativistic jet acceleration in objects like Centaurus A invokes magnetohydrodynamic simulations from Max Planck Institute for Astrophysics and computational resources at Lawrence Berkeley National Laboratory. Laboratory plasma experiments at Princeton Plasma Physics Laboratory and laser facilities at Lawrence Livermore National Laboratory test microphysical processes related to particle injection.

Cosmic rays affect galactic ecosystems linking to star-formation feedback studied at European Southern Observatory facilities and influence on galaxy evolution modeled at Max Planck Institute for Astronomy. High-energy neutrinos observed by IceCube Neutrino Observatory tie cosmic-ray sources to multimessenger campaigns coordinated with LIGO–Virgo Collaboration and Fermi Gamma-ray Space Telescope. Constraints on cosmological backgrounds derive from work at Planck (spacecraft) and impact dark matter searches pursued by Fermi Gamma-ray Space Telescope teams and experiments at Gran Sasso National Laboratory. Understanding cosmic rays informs space weather forecasting used by NOAA and mission planning at NASA Jet Propulsion Laboratory.