Cosmic-ray spectra at spherical termination shocks

V. Florinski, J. Randy Jokipii

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

We discuss the nature of the steady-state spectra of particles accelerated at stationary spherical shocks, such as the solar wind termination shock. In addition to the two well-known spectral regions characterized by a power-law momentum dependence and a high-energy cutoff, a new region can be identified. This consists of an enhancement of the cosmic-ray intensity (or a "bump") just below the cutoff. Similar features have been seen previously in multidimensional models and cosmic-ray modified shocks, where they were explained by acceleration and drift in the latitudinal direction along the shock face and decreasing effective shock compression ratio, respectively. We show that a similar bump may be obtained in a purely spherically symmetric geometry with no drifts, and that this effect may also have contributed to the previous results. We attribute this effect to increased shock acceleration efficiency at certain energies. We also demonstrate that a one-dimensional planar shock with a reflecting wall upstream can give a similar effect. We conclude that care is necessary in interpreting observed bumps in any given situation.

Original languageEnglish (US)
Pages (from-to)454-460
Number of pages7
JournalAstrophysical Journal
Volume591
Issue number1 I
DOIs
StatePublished - Jul 1 2003

Fingerprint

cosmic ray
cosmic rays
shock
energy
solar wind
momentum
power law
compression
cut-off
geometry
compression ratio
effect
upstream
augmentation
particle

Keywords

  • Acceleration of particles
  • Cosmic rays
  • Shock waves
  • Solar wind

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Cosmic-ray spectra at spherical termination shocks. / Florinski, V.; Jokipii, J. Randy.

In: Astrophysical Journal, Vol. 591, No. 1 I, 01.07.2003, p. 454-460.

Research output: Contribution to journalArticle

Florinski, V. ; Jokipii, J. Randy. / Cosmic-ray spectra at spherical termination shocks. In: Astrophysical Journal. 2003 ; Vol. 591, No. 1 I. pp. 454-460.
@article{d05fed9a5acd40488eacdcbc5bd7e399,
title = "Cosmic-ray spectra at spherical termination shocks",
abstract = "We discuss the nature of the steady-state spectra of particles accelerated at stationary spherical shocks, such as the solar wind termination shock. In addition to the two well-known spectral regions characterized by a power-law momentum dependence and a high-energy cutoff, a new region can be identified. This consists of an enhancement of the cosmic-ray intensity (or a {"}bump{"}) just below the cutoff. Similar features have been seen previously in multidimensional models and cosmic-ray modified shocks, where they were explained by acceleration and drift in the latitudinal direction along the shock face and decreasing effective shock compression ratio, respectively. We show that a similar bump may be obtained in a purely spherically symmetric geometry with no drifts, and that this effect may also have contributed to the previous results. We attribute this effect to increased shock acceleration efficiency at certain energies. We also demonstrate that a one-dimensional planar shock with a reflecting wall upstream can give a similar effect. We conclude that care is necessary in interpreting observed bumps in any given situation.",
keywords = "Acceleration of particles, Cosmic rays, Shock waves, Solar wind",
author = "V. Florinski and Jokipii, {J. Randy}",
year = "2003",
month = "7",
day = "1",
doi = "10.1086/375054",
language = "English (US)",
volume = "591",
pages = "454--460",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1 I",

}

TY - JOUR

T1 - Cosmic-ray spectra at spherical termination shocks

AU - Florinski, V.

AU - Jokipii, J. Randy

PY - 2003/7/1

Y1 - 2003/7/1

N2 - We discuss the nature of the steady-state spectra of particles accelerated at stationary spherical shocks, such as the solar wind termination shock. In addition to the two well-known spectral regions characterized by a power-law momentum dependence and a high-energy cutoff, a new region can be identified. This consists of an enhancement of the cosmic-ray intensity (or a "bump") just below the cutoff. Similar features have been seen previously in multidimensional models and cosmic-ray modified shocks, where they were explained by acceleration and drift in the latitudinal direction along the shock face and decreasing effective shock compression ratio, respectively. We show that a similar bump may be obtained in a purely spherically symmetric geometry with no drifts, and that this effect may also have contributed to the previous results. We attribute this effect to increased shock acceleration efficiency at certain energies. We also demonstrate that a one-dimensional planar shock with a reflecting wall upstream can give a similar effect. We conclude that care is necessary in interpreting observed bumps in any given situation.

AB - We discuss the nature of the steady-state spectra of particles accelerated at stationary spherical shocks, such as the solar wind termination shock. In addition to the two well-known spectral regions characterized by a power-law momentum dependence and a high-energy cutoff, a new region can be identified. This consists of an enhancement of the cosmic-ray intensity (or a "bump") just below the cutoff. Similar features have been seen previously in multidimensional models and cosmic-ray modified shocks, where they were explained by acceleration and drift in the latitudinal direction along the shock face and decreasing effective shock compression ratio, respectively. We show that a similar bump may be obtained in a purely spherically symmetric geometry with no drifts, and that this effect may also have contributed to the previous results. We attribute this effect to increased shock acceleration efficiency at certain energies. We also demonstrate that a one-dimensional planar shock with a reflecting wall upstream can give a similar effect. We conclude that care is necessary in interpreting observed bumps in any given situation.

KW - Acceleration of particles

KW - Cosmic rays

KW - Shock waves

KW - Solar wind

UR - http://www.scopus.com/inward/record.url?scp=0041654691&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0041654691&partnerID=8YFLogxK

U2 - 10.1086/375054

DO - 10.1086/375054

M3 - Article

AN - SCOPUS:0041654691

VL - 591

SP - 454

EP - 460

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1 I

ER -