Get started
Work

Acceleration of Heavy Ions at Nonrelativistic Collisionless Shocks

Year: 2025
Type: article
Abstract: We investigate the process of diffusive shock acceleration of particles with mass number to charge number ratios A / Q > 1, e.g., partially ionized heavy ions. To this end, we introduce helium- and carbon-like ions at solar abundances into two-dimensional hybrid (kinetic ions–fluid electrons) simulations of nonrelativistic collisionless shocks. This study yields three main results: (1) Heavy ions are preferentially accelerated compared to hydrogen. For typical solar abundances, the energy transferred to accelerated helium ions is comparable to, or even exceeds, that of hydrogen, thereby enhancing the overall shock acceleration efficiency. (2) Accelerated helium ions contribute to magnetic field amplification, which increases the maximum attainable particle energy and steepens the spectra of accelerated particles. (3) The efficient acceleration of helium significantly enhances the production of hadronic γ- rays and neutrinos, likely dominating the one due to hydrogen. These effects should be taken into account, especially when modeling strong space and astrophysical shocks.
DOI: 10.3847/2041-8213/ae109b
Language: English
Open Access status: gold
Estimated APC paid: $2,400
Award: ONE OF THE MOST IMPORTANT SCIENTIFIC CONTRIBUTION OF THE FERMI SATELLITE HAS BEEN TO SHOW THAT THE GAMMA-RAY EMISSION FROM SEVERAL SUPERNOVA REMNANTS (SNRS) IS OF HADRONIC ORIGIN THEREBY SUPPORTING THE IDEA THAT SNRS ARE THE SOURCES OF GALACTIC COSMIC RAYS (CRS). ALMOST ALL GEV--BRIGHT SNRS EXPAND INTO PARTIALLY-NEUTRAL MEDIA AND/OR ARE ASSOCIATED WITH DENSE MOLECULAR CLOUDS (MCS). IN THE PRESENCE OF NEUTRAL HYDROGEN THE SHOCK DYNAMICS THE SPECTRUM OF ACCELERATED PARTICLES AND THE CR--MAGNETIC FIELD COUPLING ARE RADICALLY DIFFERENT THAN IN FULLY-IONIZED PLASMAS. HOWEVER THE EFFECTS OF NEUTRALS ARE USUALLY NEGLECTED IN CALCULATIONS OF CR ACCELERATION AND PROPAGATION. WE WILL USE SELF-CONSISTENT KINETIC SIMULATIONS OF COLLISIONLESS SHOCKS PROPAGATING IN PARTIALLY-IONIZED PLASMAS TO ASSESS THE IMPACT OF PHENOMENA SUCH AS CHARGE EXCHANGE IONIZATION AND ION--NEUTRAL DAMPING ON SHOCK DYNAMICS CR ACCELERATION AND MAGNETIC FIELD AMPLIFICATION WHICH ARE NEEDED TO CHARACTERIZE THE HADRONIC GAMMA-RAY EMISSION OBSERVED IN SNR/MC SYSTEMS.
OpenAlex ID: W4415429143
FWCI: 0.945
Cites: 42
Cited by: 2
Related to: