Electron Heating, Magnetic Field Amplification, and Cosmic Ray Precursor Length at Supernova Remnant Shocks

Abstract

We investigate the observability, by direct and indirect means, of a shock precursor arising from magnetic field amplification by cosmic rays. We estimate the depth of such a precursor under conditions of nonresonant amplification, which can provide magnetic field strengths comparable to those inferred for supernova remnants. Magnetic field generation occurs as the streaming cosmic rays induce a plasma return current, and may be quenched either by nonresonant or resonant channels. In the case of nonresonant saturation, the cosmic rays become magnetized and amplification saturates at higher magnetic fields. The precursor can extend out to $10^{17}-10^{18}$ cm and is potentially detectable. If resonant saturation occurs, the cosmic rays are scattered by turbulence and the precursor length will likely be much smaller. The dependence of precursor length on shock velocity has implications for electron heating. In the case of resonant saturation, this dependence is similar to that in the more familiar resonantly generated shock precursor, which when expressed in terms of the cosmic ray diffusion coefficient $\varkappa$ and shock velocity $v_s$ is $\varkappa /v_s$. In the nonresonantly saturated case, the precursor length declines less quickly with increasing $v_s$. Where precursor length proportional to $1/v_s$ gives constant electron heating, this increased precursor length could be expected to lead to higher electron temperatures for nonresonant amplification. This should be expected at faster supernova remnant shocks than studied by previous works. Existing results and new data analysis of SN 1006 and Cas A suggest some observational support for this idea.

arXiv comment34 pages, accepted by ApJ

References in corpus (53)

• On the magnetic fields and particle acceleration in Cas A
• Magnetic Field Amplification in Tycho and other Shell-type Supernova Remnants
• Cosmic Ray Acceleration at the Forward Shock in Tycho's Supernova Remnant: Evidence from Chandra X-ray Observations
• Cosmic ray acceleration and escape from supernova remnants
• A Million-Second Chandra View of Cassiopeia A
• Chandra Detection of the Forward and Reverse Shocks in Cassiopeia-A
• A Physical Relationship Between Electron-Proton Temperature Equilibration and Mach Number in Fast Collisionless Shocks
• A Chandra X-ray Survey of Ejecta in the Cassiopeia A Supernova Remnant
• The SN 1006 Remnant: Optical Proper Motions, Deep Imaging, Distance, and Brightness at Maximum
• Non-linear Study of Bell's Cosmic Ray Current-driven Instability
• First detection of VHE gamma-rays from SN 1006 by H.E.S.S
• Electron Heating and Cosmic Rays at a Supernova Shock from Chandra X-ray Observations of E0102.2-7219
• Electron Injection by Whistler Waves in Non-relativistic Shocks
• Turbulence-induced magnetic fields and the structure of Cosmic Ray modified shocks
• The blast wave of Tycho's supernova remnant
• Characterizing the non-thermal emission of Cas A
• The Optical Spectrum of the SN 1006 Supernova Remnant Revisited
• On the Radio Polarization Signature of Efficient and Inefficient Particle Acceleration in Supernova Remnant SN 1006
• Morphological evidence for azimuthal variations of the cosmic ray ion acceleration at the blast wave of SN 1006
• Spatial Structure and Collisionless Electron Heating in Balmer-dominated Shocks
• Ion acceleration in non-relativistic astrophysical shocks
• Cosmic-ray-induced filamentation instability in collisionless shocks
• A High-Resolution X-Ray and Optical Study of SN 1006: Asymmetric Expansion and Small-Scale Structure in a Type Ia Supernova Remnant
• Universal behaviour of shock precursors in the presence of efficient cosmic-ray acceleration
• Interaction of Rayleigh-Taylor Fingers and Circumstellar Clodlets in Young Supernova Remnants
• Cosmic Ray Heating of the Warm Ionized Medium
• Magnetic Amplification by Magnetized Cosmic Rays in SNR Shocks
• Spatial structure of X-ray filaments in SN 1006
• The gas density around SN 1006
• Chandra High-Resolution X-Ray Spectrum of Supernova Remnant 1E0102.2-7219
• Turbulent magnetic field amplification driven by cosmic-ray pressure gradients
• The First X-Ray Proper-Motion Measurements of the Forward Shock in the Northeastern Limb of SN 1006
• Accelerated Electrons in Cassiopeia A: An Explanation for the Hard X-ray Tail
• Thermal emission, shock modification, and X-ray emitting ejecta in SN 1006
• The Heating of Thermal Electrons in Fast Collisionless Shocks: The Integral Role of Cosmic Rays
• On the Remote Detection of Suprathermal Ions in the Solar Corona and their Role as Seeds for Solar Energetic Particle Production
• Cosmic-Ray Acceleration Efficiency vs Temperature Equilibration: the Case of SNR 0509-67.5
• Constraints On the Diffusive Shock Acceleration From the Nonthermal X-ray Thin Shells In SN1006 NE Rim
• Accelerated Electrons in Cassiopeia A: Thermal and Electromagnetic Effects
• Postshock turbulence and diffusive shock acceleration in young supernova remnants
• The Detection of Far Ultraviolet Line Emission from Balmer-Dominated Supernova Remnants in the Large Magellanic Cloud
• Chandra Observations of Shock Kinematics in Supernova Remnant 1987A
• X-ray Proper Motions and Shock Speeds along the Northwest Rim of SN 1006
• The nonlinear saturation of the non-resonant kinetically driven streaming instability
• XMM-Newton evidence of shocked ISM in SN 1006: indications of hadronic acceleration
• Kinetic simulations of turbulent magnetic-field growth by streaming cosmic rays
• A high resolution UV absorption spectrum of supernova ejecta in SN1006
• Saturated magnetic field amplification at supernova shocks
• Mach Number Dependence of Electron Heating in High Mach Number Quasiperpendicular Shocks
• The Effect of a Cosmic Ray Precursor in SN 1006?
• Aperiodic magnetic turbulence produced by relativistic ion beams
• Could Cosmic Rays Affect Instabilities in the Transition Layer of Nonrelativistic Collisionless Shocks?
• Streaming cold cosmic ray back-reaction and thermal instabilities across the background magnetic field

Cited by in corpus (11)

• On the electron-ion temperature ratio established by collisionless shocks
• Element Abundances in the Unshocked Ejecta of Cassiopeia A
• Magnetic field amplification by collisionless shocks in partially ionized plasmas
• Injection to rapid diffusive shock acceleration at perpendicular shocks in partially ionized plasmas
• Carbon, Helium and Proton Kinetic Temperatures in a Cygnus Loop Shock Wave
• Wave Propagation at Oblique Shocks: How Did Tycho Get Its Stripes?
• X-ray Line Diagnostics of Ion Temperature at Cosmic-Ray Accelerating Collisionless Shocks
• Polarized Balmer Line Emission from Supernova Remnant Shock Waves Efficiently Accelerating Cosmic Rays
• Critical Mach Numbers for Magnetohydrodynamic Shocks with Accelerated Particles and Waves
• Electron Energization in Quasi-Parallel Shocks: Test-Particle-Electrons in a Proton Driven Turbulence
• Diagnosing Cosmic Ray Modified Shocks with H α Polarimetry