Gamma rays as probes of cosmic-ray propagation and interactions in galaxies

Abstract

Continuum gamma-ray emission produced by interactions of cosmic rays with interstellar matter and radiation fields is a probe of non-thermal particle populations in galaxies. After decades of continuous improvements in experimental techniques and an ever-increasing sky and energy coverage, gamma-ray observations reveal in unprecedented detail the properties of galactic cosmic rays. A variety of scales and environments are now accessible to us, from the local interstellar medium near the Sun and the vicinity of cosmic-ray accelerators, out to the Milky Way at large and beyond, with a growing number of gamma-ray emitting star-forming galaxies. Gamma-ray observations have been pushing forward our understanding of the life cycle of cosmic rays in galaxies and, combined with advances in related domains, they have been challenging standard assumptions in the field and have spurred new developments in modelling approaches and data analysis methods. We provide a review of the status of the subject and discuss perspectives on future progress.

Accepted for publication in the Special Issue "High-Energy Gamma-Ray Astronomy: Results on Fundamental Questions after 30 Years of Ground-Based Observations" Universe MDPI https://www.mdpi.com/journal/universe/special_issues/gamma-ray_astronomy

References in corpus (101)

• The NumPy array: a structure for efficient numerical computation
• Observation of an anomalous positron abundance in the cosmic radiation
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Painting a portrait of the Galactic disc with its stellar clusters
• Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of electrons and positrons
• Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
• eROSITA Science Book: Mapping the Structure of the Energetic Universe
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• Background Modelling in Very-High-Energy gamma-ray Astronomy
• Parametrization of gamma-ray production cross-sections for pp interactions in a broad proton energy range from the kinematic threshold to PeV energies
• Parameterization of Gamma, e^+/- and Neutrino Spectra Produced by p-p Interaction in Astronomical Environment
• The Spectrum and Morphology of the Fermi Bubbles
• Measurement of the cosmic-ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite
• Global cosmic-ray related luminosity and energy budget of the Milky Way
• Spectral breaks as a signature of cosmic ray induced turbulence in the Galaxy
• Inverse Compton Origin of the Hard X-Ray and Soft Gamma-Ray Emission from the Galactic Ridge
• First Detection of sub-PeV Diffuse Gamma Rays from the Galactic Disk: Evidence for Ubiquitous Galactic Cosmic Rays beyond PeV Energies
• Cosmic Ray Propagation: Nonlinear Diffusion Parallel and Perpendicular to Mean Magnetic Field
• Detection of Gamma Rays From a Starburst Galaxy
• CO-dark gas and molecular filaments in Milky Way type galaxies
• Cosmic-ray propagation with DRAGON2: I. numerical solver and astrophysical ingredients
• The Large Scale Cosmic-Ray Anisotropy as Observed with Milagro
• Molecular clouds towards RCW 49 and Westerlund 2; Evidence for cluster formation triggered by cloud-cloud collision
• A radiation transfer model for the Milky-Way: I. Radiation fields and application to High Energy Astrophysics
• Gamma rays from molecular clouds
• Cosmic rays and the magnetic field of the nearby starburst galaxy NGC 253
• Gamma-ray sky points to radial gradients in cosmic-ray transport
• Particle acceleration in winds of star clusters
• Observation of Cosmic Ray Anisotropy with the IceTop Air Shower Array
• Absorption of Very High Energy Gamma Rays in the Milky Way
• Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33
• AMS-02 beryllium data and its implication for cosmic ray transport
• High-Energy Gamma Rays from the Milky Way: Three-Dimensional Spatial Models for the Cosmic-Ray and Radiation Field Densities in the Interstellar Medium
• Scrutinizing the evidence for dark matter in cosmic-ray antiprotons
• HAWC observations of the acceleration of very-high-energy cosmic rays in the Cygnus Cocoon
• Identification of the TeV Gamma-ray Source ARGO J2031+4157 with the Cygnus Cocoon
• Observations of M31 and M33 with the Fermi Large Area Telescope: a galactic center excess in Andromeda?
• Winds, Clumps, and Interacting Cosmic Rays in M82
• The Massive Star Content of NGC 3603
• A common solution to the cosmic ray anisotropy and gradient problems
• Cosmic ray transport in starburst galaxies
• Northern sky Galactic Cosmic Ray anisotropy between 10-1000 TeV with the Tibet Air Shower Array
• The low rate of Galactic pevatrons
• CO-dark molecular gas at high redshift: very large H${}_2$ content and high pressure in a low metallicity damped Lyman-alpha system
• Galactic halo size in the light of recent AMS-02 data
• NE2001. II. Using Radio Propagation Data to Construct a Model for the Galactic Distribution of Free Electrons
• Simulating Gamma-ray Emission in Star-forming Galaxies
• Cosmic-Ray Propagation in Light of Recent Observation of Geminga
• Plasma turbulence in the interstellar medium
• A signature of anisotropic cosmic-ray transport in the gamma-ray sky
• Detailed Investigation of the Gamma-Ray Emission in the Vicinity of SNR W28 with FERMI-LAT
• Search for Gamma-ray Emission from Dark Matter Annihilation in the Large Magellanic Cloud with the Fermi Large Area Telescope
• Numerical propagation of high energy cosmic rays in the Galaxy I: technical issues
• Spatially Resolving a Starburst Galaxy at Hard X-ray Energies: NuSTAR, Chandra, AND VLBA Observations of NGC 253
• Non-linear diffusion of cosmic rays escaping from supernova remnants - II. Hot ionized media
• Gamma-ray Astrophysics in the MeV Range: the ASTROGAM Concept and Beyond
• Starburst galaxies strike back: a multi-messenger analysis with Fermi-LAT and IceCube data
• Power requirements for cosmic ray propagation models involving diffusive reacceleration; estimates and implications for the damping of interstellar turbulence
• Source population synthesis and the Galactic diffuse gamma-ray emission
• Fermi-LAT Observations of High- and Intermediate-Velocity Clouds: Tracing Cosmic Rays in the Halo of the Milky Way
• The Mopra Southern Galactic Plane CO Survey - Data Release 3
• Gamma-ray observations of the Orion Molecular Clouds with the Fermi Large Area Telescope
• Nuclear enhancement of the photon yield in cosmic ray interactions
• Spiral Arms as Cosmic Ray Source Distributions
• Galactic Cosmic Ray Origins and OB Associations: Evidence from SuperTIGER Observations of Elements ${}_{26}$Fe through ${}_{40}$Zr
• Propagation in 3D spiral-arm cosmic-ray source distribution models and secondary particle production using PICARD
• The theory of cosmic-ray scattering on pre-existing MHD modes meets data
• Validation of open-source science tools and background model construction in $\gamma$-ray astronomy
• The Age of Westerlund 1 Revisited
• Disentangling the spatial substructure of Cygnus OB2 from Gaia DR2
• Diffuse γ-ray emission from self-confined cosmic rays around Galactic sources
• Diffuse gamma-ray emission toward the massive star-forming region, W40
• Escape of cosmic rays from the Galaxy and effects on the circumgalactic medium
• The gamma-ray / infrared luminosity correlation of star-forming galaxies
• Morphological and spectral study of 4FGL J1115.1-6118 in the region of the young massive stellar cluster NGC 3603
• The diffuse gamma-ray emission toward the Galactic mini starburst W43
• A Run-Wise Simulation and Analysis Framework for Imaging Atmospheric Cherenkov Telescope Arrays
• Spectral and morphological study of the gamma radiation of the middle-aged supernova remnant HB 21
• Probing the Cosmic Ray density in the inner Galaxy
• Constraints on the TeV source population and its contribution to the galactic diffuse TeV emission
• Evidence of Cosmic-Ray Excess from Local Giant Molecular Clouds
• Using Interstellar Clouds to Search for Galactic PeVatrons: Gamma-ray Signatures from Supernova Remnants
• Molecular Clouds as the Origin of the Fermi Gamma-Ray GeV-Excess
• Implications on Spatial Models of Interstellar Gamma-Ray Inverse-Compton Emission from Synchrotron Emission Studies in Radio and Microwaves
• Can a cosmic ray carrot explain the ionization level in diffuse molecular clouds?
• Evaluation of Production Cross Sections of Li, Be, B in CR
• Does the SN rate explain the very high energy cosmic rays in the central 200 pc of our Galaxy?
• On the Physics Connecting Cosmic Rays and Gamma Rays: Towards Determining the Interstellar Cosmic Ray Spectrum
• Nuclear de-excitation lines as a probe of low-energy cosmic rays
• OH as an Alternate Tracer for Molecular Gas: Quantity and Structure of Molecular Gas in W5
• Quantifying the Interstellar Medium and Cosmic Rays in the MBM 53, 54, and 55 Molecular Clouds and the Pegasus Loop using Fermi-LAT Gamma-ray Observations
• Local interstellar cosmic-ray spectra derived from gamma-ray emissivities
• Diffuse Gamma Rays in 3D Galactic Cosmic-ray Propagation Models
• Spectral components analysis of diffuse emission processes
• Probing the star formation origin of gamma rays from 3FHL J1907.0+0713
• Study of the Cosmic Rays and Interstellar Medium in Local HI Clouds using Fermi-LAT Gamma-Ray Observations
• Time-dependent escape of cosmic rays from supernova remnants potentially at the origin of the very-high-energy cosmic-ray gradient of the Galactic center
• Role of Polycyclic Aromatic Hydrocarbons on the Cosmic-Ray ionization rate in the Galaxy
• Cosmic Rays and Interstellar Medium with Gamma-Ray Observations at MeV Energies

Cited by in corpus (31)

• The Hunt for Pevatrons: The Case of Supernova Remnants
• Cosmic ray production in superbubbles
• Cosmic rays in molecular clouds probed by H${}_2$ rovibrational lines -- Perspectives for the James Webb Space Telescope
• First Predicted Cosmic Ray Spectra, Primary-to-Secondary Ratios, and Ionization Rates from MHD Galaxy Formation Simulations
• Standard Self-Confinement and Extrinsic Turbulence Models for Cosmic Ray Transport are Fundamentally Incompatible with Observations
• Regimes of cosmic-ray diffusion in Galactic turbulence
• Low energy cosmic rays
• Diffuse Emission of Galactic High-Energy Neutrinos from a Global Fit of Cosmic Rays
• Galactic diffuse gamma-ray emission from GeV to PeV energies in light of up-to-date cosmic ray measurements
• Are pulsar halos rare ?
• Constraining Cosmic-ray Transport with Observations of the Circumgalactic Medium
• Bayesian inference of three-dimensional gas maps: II. Galactic HI
• Multiple emission components in the Cygnus cocoon detected from Fermi-LAT observations
• Ultrahigh-energy diffuse gamma-ray emission from cosmic-ray interactions with medium surrounding acceleration sources
• Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic Cloud
• Prospects for a survey of the Galactic plane with the Cherenkov Telescope Array
• New determination of the production cross section for $\gamma$ rays in the Galaxy
• Multi-TeV dark matter density in the inner Milky Way halo: spectral and dynamical constraints
• A new analytic approach to infer the cosmic-ray ionization rate in hot molecular cores from HCO${}^{+}$, N${}_2$H${}^{+}$, and CO observations
• Multi-Component Imaging of the Fermi Gamma-ray Sky in the Spatio-spectral Domain
• The extragalactic $\gamma$-ray background: imprints from the physical properties and evolution of star-forming galaxy populations
• Weighing the Local Interstellar Medium using Gamma Rays and Dust
• Self-modulation of cosmic rays in molecular clouds: Imprints in the radio observations
• Energetic particles and high-energy processes in cosmological filaments and their astronomical implications
• Cosmic rays, gas and dust in the Central Molecular Zone I -- $X_{CO}$ factors, cosmic-ray densities and dust opacities
• Pulsar+escape: the recipe for LHAASO sources ?
• The influence of the 3D Galactic gas structure on cosmic-ray transport and $\gamma$-ray emission
• Search for H2 cloudlets in our backyard
• Stochastic modelling of cosmic-ray sources for Galactic diffuse emissions
• Constraining the position of the knee in the galactic cosmic ray spectrum with ultra-high-energy diffuse $\gamma$-rays
• Exploring the nature of Galactic unassociated sources detected by the Fermi-LAT