Polarized Balmer Line Emission from Supernova Remnant Shock Waves Efficiently Accelerating Cosmic Rays

Abstract

Linearly polarized Balmer line emissions from supernova remnant shocks are studied taking into account the energy loss of the shock owing to the production of nonthermal particles. The polarization degree depends on the downstream temperature and the velocity difference between upstream and downstream regions. The former is derived once the line width of the broad component of the H$\alpha$ emission is observed. Then, the observation of the polarization degree tells us the latter. At the same time, the estimated value of the velocity difference independently predicts adiabatic downstream temperature that is derived from Rankine-Hugoniot relations for adiabatic shocks. If the actually observed downstream temperature is lower than the adiabatic temperature, there is a missing thermal energy which is consumed for particle acceleration. It is shown that a larger energy loss rate leads to more highly polarized H$\alpha$ emission. Furthermore, we find that polarized intensity ratio of H$\beta$ to H$\alpha$ also depends on the energy loss rate and that it is independent of uncertain quantities such as electron temperature, the effect of Lyman line trapping and our line of sight.

arXiv comment15 pages, accepted by MNRAS

References in corpus (37)

• Cosmic Ray Acceleration at the Forward Shock in Tycho's Supernova Remnant: Evidence from Chandra X-ray Observations
• Balmer-Dominated Spectra of Nonradiative Shocks in the Cygnus Loop, RCW 86 and Tycho Supernova Remnants
• Measuring the cosmic ray acceleration efficiency of a supernova remnant
• The blast wave of Tycho's supernova remnant
• The Optical Spectrum of the SN 1006 Supernova Remnant Revisited
• Balmer-Dominated Shocks: A Concise Review
• Spatial Structure and Collisionless Electron Heating in Balmer-dominated Shocks
• Expansion Velocity of Ejecta in Tycho's Supernova Remnant Measured by Doppler Broadened X-ray Line Emission
• X-Ray Measured Dynamics of Tycho's Supernova Remnant
• Fluid dynamics of partially radiative blast waves
• Collisionless shocks in a partially ionized medium: I. Neutral return flux and its effects on acceleration of test particles
• Evidence for nonlinear diffusive shock acceleration of cosmic-rays in the 2006 outburst of the recurrent nova RS Ophiuchi
• Resolved shock structure of the Balmer-dominated filaments in Tycho's supernova remnant: Cosmic-ray precursor?
• Origin of Radially Aligned Magnetic Fields in Young Supernova Remnants
• Balmer-Dominated Shocks Revisited
• SUBARU HDS Observations of a Balmer-Dominated Shock in Tycho's Supernova Remnant
• Proper Motions of H-alpha filaments in the Supernova Remnant RCW 86
• The Heating of Thermal Electrons in Fast Collisionless Shocks: The Integral Role of Cosmic Rays
• On cosmic-ray production efficiency at supernova remnant shocks propagating into realistic diffuse interstellar medium
• Collisionless shock in a partially ionized medium. II. Balmer emission
• Collisionless shocks in a partially ionized medium: III. Efficient cosmic ray acceleration
• RJK Observations of the Optical Afterglow of GRB 991216
• Oblique Ion Two-Stream Instability in the Foot Region of a Collisionless Shock
• Absence of Electron Surfing Acceleration in a Two-Dimensional Simulation
• Effects of Leakage Neutral Particles on Shocks
• Excitation and charge transfer in hydrogen-proton collisions at 5--80 keV and application to astrophysical shocks
• Magnetic field amplification by collisionless shocks in partially ionized plasmas
• Injection to rapid diffusive shock acceleration at perpendicular shocks in partially ionized plasmas
• Broad Lyman-Alpha Emission from Supernova Remnants in Young Galaxies
• Simulations of Collisionless Perpendicular Shocks in Partially Ionized Plasmas
• Cosmic Ray acceleration and Balmer emission from SNR 0509-67.5
• Electron Heating, Magnetic Field Amplification, and Cosmic Ray Precursor Length at Supernova Remnant Shocks
• Spatially-Resolved Spectroscopy of a Balmer-Dominated Shock in the Cygnus Loop: An Extremely Thin Cosmic-Ray Precursor?
• Cosmic Ray acceleration and Balmer emission from RCW 86 (G315.4-2.3)
• Acoustic instability in the neutral precursor region of collisionless shocks propagating into partially ionized plasmas
• Discovery of polarized line emission in SN1006
• H$\alpha$ Imaging spectroscopy of Balmer-dominated shocks in Tycho's supernova remnant

Cited by in corpus (5)

• Element Abundances: A New Diagnostic for the Solar Wind
• Electron-Ion Temperature Ratio in Astrophysical Shocks
• X-ray Line Diagnostics of Ion Temperature at Cosmic-Ray Accelerating Collisionless Shocks
• Radiative transfer of hydrogen lines from supernova remnant shock waves: contributions of 2s-state hydrogen atoms
• Diagnosing Cosmic Ray Modified Shocks with H α Polarimetry