A Physical Relationship between Electron-Proton Temperature Equilibration and Mach Number in Fast Collisionless Shocks

By P. Ghavamian, J. Laming, C. Rakowski. 2006

175 citations recorded by the source corpus.

The analysis of Balmer-dominated optical spectra from nonradiative (adiabatic) SNRs has shown that the ratio of the electron to proton temperature at the blast wave is close to unity at vS ≲ 400 km s-1 but declines sharply down to the minimum value of me/mp dictated by the jump conditions at shock speeds exceeding 2000 km s-1. We propose a physical model for the heating of electrons and ions in non-cosmic-ray-dominated, strong shocks (vS > 400 km s-1) wherein the electrons are heated by lower hybrid waves immediately ahead of the shock front. These waves arise naturally from the cosmic ray pressure gradient upstream from the shock. Our model predicts a nearly constant level of electron heating over a wide range of shock speeds, producing a relationship (Te/Tp)0 ∝ v (∝M-2) that is fully consistent with the observations.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/ec84ca393dc3dc2a3ac586a90b9365fe59ee9bd0

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. C. Faucher-Giguére
2. E. Quataert
3. A. Spitkovsky
4. P. Hopkins
5. D. Caprioli
6. A. Bykov
7. J. Vink
8. J. C. Raymond

In Nuclear and High Energy Physics

1. A. Spitkovsky
2. D. Caprioli
3. E. Quataert
4. C. Faucher-Giguére
5. A. Bykov
6. J. Vink
7. J. C. Raymond
8. Y. Ohira

Citations in the corpus

• SIMULATIONS OF ION ACCELERATION AT NON-RELATIVISTIC SHOCKS. I. ACCELERATION EFFICIENCY (2013, background): “The ion temperature in collisionless shocks may be directly probed by measuring the optical H-α emission produced in SNRs expanding into partially-neutral media (see, e.g., Ghavamian et al. 2007; Blasi et al. 2012).”
• The physics of galactic winds driven by active galactic nuclei (2012, background): “Observations of supernova remnants in fact indicate that the electrons and protons can be significantly decoupled after fast shocks (e.g., Ghavamian et al. 2007), as is also the case in the solar wind (e.g., Schwartz et al. 1988).”
• Observational Signatures of Particle Acceleration in Supernova Remnants (2012, methodology): “From optical observations, a relation of 1/V 2s was proposed for Vs > 400 km s −1, below 400 km s−1 the electron and proton temperature were similar (Ghavamian et al., 2007) (however, see van Adelsberg et al., 2008; Helder et al., 2011).”
• Supernova remnants: the X-ray perspective (2011, background): “Optical spectroscopy of SNR shocks show mixed results with indications that full equilibration is important fo Vs < 500 km s−1, and non-equilibration for higher velocities (Ghavamian et al., 2007; Helder et al., 2011).”
• The origin of galactic cosmic rays (2013, unknown): “On the other hand, for such fast shocks, it is found that βdown 1 (Ghavamian et al. 2007, 2013), in which case one can see that acceleration efficiencies of ∼10–20 % can be inferred from the measured FWHM.”