scholarly journals The impact of astrophysical dust grains on the confinement of cosmic rays

2021 ◽  
Vol 502 (2) ◽  
pp. 2630-2644
Author(s):  
Jonathan Squire ◽  
Philip F Hopkins ◽  
Eliot Quataert ◽  
Philipp Kempski
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Alfven Waves ◽  
Feedback Mechanism ◽  
Alfvén Waves ◽  
Small Scale ◽  
Charged Dust ◽  
Dust Grains ◽  
The Impact

ABSTRACT We argue that charged dust grains could significantly impact the confinement and transport of galactic cosmic rays. For sub-GeV to ∼103 GeV cosmic rays, small-scale parallel Alfvén waves, which isotropize cosmic rays through gyro-resonant interactions, are also gyro-resonant with charged grains. If the dust is nearly stationary, as in the bulk of the interstellar medium, Alfvén waves are damped by dust. This will reduce the amplitude of Alfvén waves produced by the cosmic rays through the streaming instability, thus enhancing cosmic ray transport. In well-ionized regions, the dust damping rate is larger by a factor of ∼10 than other mechanisms that damp parallel Alfvén waves at the scales relevant for ∼GeV cosmic rays, suggesting that dust could play a key role in regulating cosmic ray transport. In astrophysical situations in which the dust moves through the gas with super-Alfvénic velocities, Alfvén waves are rendered unstable, which could directly scatter cosmic rays. This interaction has the potential to create a strong feedback mechanism where dust, driven through the gas by radiation pressure, then strongly enhances the confinement of cosmic rays, increasing their capacity to drive outflows. This mechanism may act in the circumgalactic medium around star-forming galaxies and active galactic nuclei.

Magnetohydrodynamic plasma instability driven by Alfvén waves excited by cosmic rays

1984 ◽  
Vol 31 (2) ◽  
pp. 275-299 ◽  
Author(s):  
J. F. McKenzie ◽  
G. M. Webb
Keyword(s):  
Cosmic Rays ◽  
Thermal Plasma ◽  
Cosmic Ray ◽  
Nonlinear Damping ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Shock Acceleration ◽  
Alfvén Waves ◽  
Wave Growth ◽  
Streaming Instability

Hydrodynamical equations describing the mutual interaction of cosmic rays, thermal plasma, magnetic field and Alfvén waves scattering the cosmic rays used in cosmic ray shock acceleration theory (e.g. McKenzie & Völk 1982; Drury 1983; Webb 1983) are analysed for long-wavelength linear compressive instabilities. The Alfvén wave field may contain a pre-existing component as well as a component excited by the cosmic ray streaming instability. In the case of no Alfvén wave damping, adiabatic wave growth and Alfvén wave generation by the cosmic ray streaming instability, it is found that the backward propagating slow magneto-acoustic mode is driven convectively unstable by the pressure of the self-excited Alfvén waves, provided the thermal plasmaβis sufficiently large. The equations are also analysed for the case where the Alfvén wave growth is balanced by some nonlinear damping mechanisms. In the latter case both the forward and backward propagating slow magneto-acoustic modes may be driven unstable if the plasmaβis sufficiently small. The conditions under which the instabilities occur are delineated, and sample calculations of growth rates given. Possible applications of the instabilities to astrophysical situations are briefly discussed.

scholarly journals Time-Dependent Simulation of Cosmic-Ray Shocks, Including Alfvén Transport

1994 ◽  
Vol 142 ◽  
pp. 969-973
Author(s):  
T. W. Jones
Keyword(s):  
Diffusion Coefficient ◽  
Cosmic Rays ◽  
Wave Energy ◽  
Cosmic Ray ◽  
Alfven Waves ◽  
Alfven Wave ◽  
Alfvén Waves ◽  
Constant Diffusion Coefficient ◽  
Constant Diffusion ◽  
Transport Effects

AbstractTime evolution of plane, cosmic-ray modified shocks has been simulated numerically for the case with parallel magnetic fields. Computations were done in a “three-fluid” dynamical model incorporating cosmic-ray and Alfvén-wave energy transport equations. Nonlinear feedback from the cosmic rays and Alfvén waves is included in the equation of motion for the underlying plasma, as is the finite propagation speed and energy dissipation of the Alfvén waves. Exploratory results confirm earlier, steady state analyses that found these Alfvén transport effects to be potentially important when the upstream Alfvén speed and gas sound speeds are comparable. As noted earlier, Alfvén transport effects tend to reduce the transfer of energy through a shock from gas to energetic particles. These studies show as well that the timescale for modification of the shock is altered in nonlinear ways. It is clear, however, that the consequences of Alfvén transport are strongly model dependent and that both advection of cosmic rays by the waves and dissipation of wave energy in the plasma will be important to model correctly when quantitative results are needed. Comparison is made between simulations based on a constant diffusion coefficient and more realistic diffusion models allowing the diffusion coefficient to vary in response to changes in Alfvén wave intensity. No really substantive differences were found between them.Subject headings: cosmic rays — MHD — shock waves

scholarly journals Atmospheric changes caused by galactic cosmic rays over the period 1960–2010

2016 ◽  
Vol 16 (9) ◽  
pp. 5853-5866 ◽  
Author(s):  
Charles H. Jackman ◽  
Daniel R. Marsh ◽  
Douglas E. Kinnison ◽  
Christopher J. Mertens ◽  
Eric L. Fleming
Keyword(s):  
Cosmic Rays ◽  
Climate Model ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Sulfate Aerosol ◽  
Solar Cycle Variation ◽  
Aerosol Loading ◽  
Ion Production ◽  
Column Ozone ◽  
The Impact

Abstract. The Specified Dynamics version of the Whole Atmosphere Community Climate Model (SD-WACCM) and the Goddard Space Flight Center two-dimensional (GSFC 2-D) models are used to investigate the effect of galactic cosmic rays (GCRs) on the atmosphere over the 1960–2010 time period. The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) computation of the GCR-caused ionization rates are used in these simulations. GCR-caused maximum NOx increases of 4–15 % are computed in the Southern polar troposphere with associated ozone increases of 1–2 %. NOx increases of  ∼ 1–6 % are calculated for the lower stratosphere with associated ozone decreases of 0.2–1 %. The primary impact of GCRs on ozone was due to their production of NOx. The impact of GCRs varies with the atmospheric chlorine loading, sulfate aerosol loading, and solar cycle variation. Because of the interference between the NOx and ClOx ozone loss cycles (e.g., the ClO + NO2+ M  →  ClONO2+ M reaction) and the change in the importance of ClOx in the ozone budget, GCRs cause larger atmospheric impacts with less chlorine loading. GCRs also cause larger atmospheric impacts with less sulfate aerosol loading and for years closer to solar minimum. GCR-caused decreases of annual average global total ozone (AAGTO) were computed to be 0.2 % or less with GCR-caused column ozone increases between 1000 and 100 hPa of 0.08 % or less and GCR-caused column ozone decreases between 100 and 1 hPa of 0.23 % or less. Although these computed ozone impacts are small, GCRs provide a natural influence on ozone and need to be quantified over long time periods. This result serves as a lower limit because of the use of the ionization model NAIRAS/HZETRN which underestimates the ion production by neglecting electromagnetic and muon branches of the cosmic ray induced cascade. This will be corrected in future works.

scholarly journals Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite

2019 ◽  
Vol 5 (9) ◽  
pp. eaax3793 ◽  
Author(s):  
◽  
Q. An ◽  
R. Asfandiyarov ◽  
P. Azzarello ◽  
P. Bernardini ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Cosmic Radiation ◽  
Precise Measurement ◽  
Milky Way ◽  
Spectral Feature ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Proton Spectrum ◽  
First Time

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

Atmospheric production and transport of 7Be activity by cosmic rays: Modelling with the chemistry-climate model SOCOLv3.0 and comparison with direct measurements

2021 ◽  
Author(s):  
Kseniia Golubenko ◽  
Eugene Rozanov ◽  
Genady Kovaltsov ◽  
Ari-Pekka Leppänen ◽  
Ilya Usoskin
Keyword(s):  
Cosmic Rays ◽  
Climate Changes ◽  
Climate Model ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Cosmogenic Isotopes ◽  
Cosmogenic Isotope ◽  
The Past ◽  
Direct Measurements ◽  
First Results

<p>We present the first results of modelling of the short-living cosmogenic isotope <sup>7</sup>Be production, deposition, and transport using the chemistry-climate model SOCOLv<sub>3.0</sub> aimed to study solar-terrestrial interactions and climate changes. We implemented an interactive deposition scheme,  based on gas tracers with and without nudging to the known meteorological fields. Production of <sup>7</sup>Be was modelled using the 3D time-dependent Cosmic Ray induced Atmospheric Cascade (CRAC) model. The simulations were compared with the real concentrations (activity) and depositions measurements of <sup>7</sup>Be in the air and water at Finnish stations. We have successfully reproduced and estimated the variability of the cosmogenic isotope <sup>7</sup>Be produced by the galactic cosmic rays (GCR) on time scales longer than about a month, for the period of 2002–2008. The agreement between the modelled and measured data is very good (within 12%) providing a solid validation for the ability of the SOCOL CCM to reliably model production, transport, and deposition of cosmogenic isotopes, which is needed for precise studies of cosmic-ray variability in the past. </p>

scholarly journals Particle Acceleration by Supernova Shocks and Spallogenic Nucleosynthesis of Light Elements

2018 ◽  
Vol 68 (1) ◽  
pp. 377-404 ◽  
Author(s):  
Vincent Tatischeff ◽  
Stefano Gabici
Keyword(s):  
Cosmic Rays ◽  
Light Element ◽  
Cosmic Ray ◽  
Nuclear Interaction ◽  
Galactic Cosmic Rays ◽  
Light Elements ◽  
Halo Stars ◽  
The Standard Model ◽  
Low Metallicity ◽  
Galactic Cosmic Ray

In this review, we first reassess the supernova remnant paradigm for the origin of Galactic cosmic rays in the light of recent cosmic-ray data acquired by the Voyager 1 spacecraft. We then describe the theory of light-element nucleosynthesis by nuclear interaction of cosmic rays with the interstellar medium and outline the problem of explaining the measured beryllium abundances in old halo stars of low metallicity with the standard model of the Galactic cosmic-ray origin. We then discuss the various cosmic-ray models proposed in the literature to account for the measured evolution of the light elements in the Milky Way, and point out the difficulties that they all encounter. It seems to us that, among all possibilities, the superbubble model provides the most satisfactory explanation for these observations.

scholarly journals The impact of solar and galactic cosmic rays on atmospheric vortex structures

2017 ◽  
Vol 14 (2) ◽  
pp. 209-220
Author(s):  
N.I. Izhovkina ◽  
◽  
S.N. Artekha ◽  
N.S. Erokhin ◽  
L.A. Mikhailovskaya ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Galactic Cosmic Rays ◽  
Vortex Structures ◽  
The Impact

scholarly journals Short- and Medium-Term Induced Ionization in the Earth Atmosphere by Galactic and Solar Cosmic Rays

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Alexander Mishev
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
Ground Level ◽  
Galactic Cosmic Rays ◽  
Earth Atmosphere ◽  
Medium Term ◽  
Ground Level Enhancement ◽  
Solar Cosmic Rays ◽  
The Earth ◽  
Ionization Effect

The galactic cosmic rays are the main source of ionization in the troposphere of the Earth. Solar energetic particles of MeV energies cause an excess of ionization in the atmosphere, specifically over polar caps. The ionization effect during the major ground level enhancement 69 on January 20, 2005 is studied at various time scales. The estimation of ion rate is based on a recent numerical model for cosmic-ray-induced ionization. The ionization effect in the Earth atmosphere is obtained on the basis of solar proton energy spectra, reconstructed from GOES 11 measurements and subsequent full Monte Carlo simulation of cosmic-ray-induced atmospheric cascade. The evolution of atmospheric cascade is performed with CORSIKA 6.990 code using FLUKA 2011 and QGSJET II hadron interaction models. The atmospheric ion rate is explicitly obtained for various latitudes, namely, 40°N, 60°N and 80°N. The time evolution of obtained ion rates is presented. The short- and medium-term ionization effect is compared with the average effect due to galactic cosmic rays. It is demonstrated that ionization effect is significant only in subpolar and polar atmosphere during the major ground level enhancement of January 20, 2005. It is negative in troposphere at midlatitude, because of the accompanying Forbush effect.

A reevaluation of the atmospheric pressure dependence of secondary cosmic-ray neutrons in the context of Cosmic-Ray Neutron Sensing

2021 ◽  
Author(s):  
Jannis Weimar ◽  
Paul Schattan ◽  
Martin Schrön ◽  
Markus Köhli ◽  
Rebecca Gugerli ◽  
...  
Keyword(s):  
Cosmic Rays ◽  
Hydrogen Content ◽  
Atmospheric Pressure ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Atmospheric Air ◽  
Neutron Intensity ◽  
The Earth ◽  
Wide Range ◽  
Primary Cosmic Rays

<p><span>Secondary cosmic-ray neutrons may be effectively used as a proxy for environmental hydrogen content at the hectare scale. These neutrons are generated mostly in the upper layers of the atmosphere within particle showers induced by galactic cosmic rays and other secondary particles. Below 15 km altitude their intensity declines as primary cosmic rays become less abundant and the generated neutrons are attenuated by the atmospheric air. At the earth surface, the intensity of secondary cosmic-ray neutrons heavily depends on their attenuation within the atmosphere, i.e. the amount of air the neutrons and their precursors pass through. Local atmospheric pressure measurements present an effective means to account for the varying neutron attenuation potential of the atmospheric air column above the neutron sensor. Pressure variations possess the second largest impact on the above-ground epithermal neutron intensity. Thus, using epithermal neutrons to infer environmental hydrogen content requires precise knowledge on how to correct for atmospheric pressure changes.</span></p><p><span>We conducted several short-term field experiments in saturated environments and at different altitudes, i.e. different pressure states to observe the neutron intensity pressure relation over a wide range of pressure values. Moreover, we used long-term measurements above glaciers in order to monitor the local dependence of neutron intensities and pressure in a pressure range typically found in Cosmic-Ray Neutron Sensing. The results are presented along with a broad Monte Carlo simulation campaign using MCNP 6. In these simulations, primary cosmic rays are released above the earth atmosphere at different cut-off rigidities capturing the whole evolution of cosmic-ray neutrons from generation to attenuation and annihilation. The simulated and experimentally derived pressure relation of cosmic-ray neutrons is compared to those of similar studies and assessed in the light of an appropriate atmospheric pressure correction for Cosmic-Ray Neutron Sensing.</span></p>

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